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1.
Chen SP Wu JL Su YC Hong JR 《Apoptosis : an international journal on programmed cell death》2007,12(6):1043-1060
Nervous necrosis virus (NNV)-induced, host cell apoptosis mediates secondary necrosis by an ill-understood process. In this
study, redspotted grouper nervous necrosis virus (RGNNV) is shown to induce mitochondria-mediated necrotic cell death in GL-av
cells (fish cells) via cytochrome c release, and anti-apoptotic proteins are shown to protect these cells from death. Western blots revealed that cytochrome
c release coincided with disruption of mitochondrial ultrastructure and preceded necrosis, but did not correlate with caspases
activation. To identify the mediator(s) of this necrotic process, a protein synthesis inhibitor (cycloheximide; CHX; 0.33 μg/ml)
was used to block cytochrome c release as well as PS exposure and mitochondrial membrane permeability transition pore (MMP) loss. CHX (0.33 μg/ml) completely
blocked viral protein B2 expression, and partly blocked protein A, protein α, and a pro-apoptotic death protein (Bad) expression.
Overexpression of B2 gene increased necrotic-like cell death up to 30% at 48 h post-transfection, suggesting that newly synthesized protein (B2)
may be involved in this necrotic process. Finally, necrotic death was prevented by overexpression of Bcl-2 family proteins,
zfBcl-xL and xfMcl-1a. Thus, new protein synthesis and release of cytochrome c are required for RGNNV-induced necrotic cell death, which can be blocked by anti-apoptotic Bcl-2 members.
J.-L. Wu and J.-R. Hong contributed equally to the research. 相似文献
2.
José M. García-Heredia Antonio Díaz-Quintana Maria Salzano Mar Orzáez Enrique Pérez-Payá Miguel Teixeira Miguel A. De la Rosa Irene Díaz-Moreno 《Journal of biological inorganic chemistry》2011,16(8):1155-1168
Cytochrome c (Cc) is a key protein in cell life (respiration) and cell death (apoptosis). On the one hand, it serves as a mitochondrial redox
carrier, transferring electrons between the membrane-embedded complexes III and IV. On the other hand, it acts as a cytoplasmic
apoptosis-triggering agent, forming the apoptosome with apoptosis protease-activating factor-1 (Apaf-1) and activating the
caspase cascade. The two functions of cytochrome c are finely tuned by the phosphorylation of tyrosines and, in particular, those located at positions 48 and 97. However, the
specific cytochrome c-phosphorylating kinase is still unknown. To study the structural and functional changes induced by tyrosine phosphorylation
in cytochrome c, we studied the two phosphomimetic mutants Y48E and Y97E, in which each tyrosine residue is replaced by glutamate. Such substitutions
alter both the physicochemical features and the function of each mutant compared with the native protein. Y97E is significantly
less stable than the WT species, whereas Y48E not only exhibits lower values for the alkaline transition pK
a and the midpoint redox potential, but it also impairs Apaf-1-mediated caspase activation. Altogether, these findings suggest
that the specific phosphorylation of Tyr48 makes cytochrome c act as an anti-apoptotic switch. 相似文献
3.
E. P. Isakova Yu. I. Deryabina N. N. Gessler T. A. Belozerskaya Ya. M. Rabinovich 《Applied Biochemistry and Microbiology》2010,46(3):318-323
Cell respiratory activity of protoplasts obtained from the wild type of Neurospora crassa and photoreceptor complex WCC—white collar 1 (wc-1) and white collar 2 (wc-2)—mutants of Neurospora crassa strains was investigated. Respiration inhibition by KCN in the presence of 25 mM succinate was similar in all strains and
did not exceed 83–85% against control. The significant induction of KCN-resistant respiratory pathway occurred under 1% glucose
oxidation in wc-1 and wc-2 mutants if compared with the wild type strains. The inhibitors of the main (cytochrome) pathway of electron transfer in mitochondria—1
mM KCN and antimycin A (4 μg/ml)—blocked the respiration rate of the protoplasts from N. crassa wild type by 75%, while the cell respiration of wc-1 and wc-2 strains was suppressed by approximately 50%. The specific inhibitor of alternative oxidase—10 mM salicylhydroxamic acid (SHAM)—in
combination with the blockers of mitochondrial electron transfer chain caused the total suppression of respiratory activity
of protoplasts in all studied strains. It is supposed that an increase of KCN-resistance in WCC mutants under glucose oxidation
is connected with alternative oxidase activation as the result of failure in reception and signal transduction of active oxygen
species. 相似文献
4.
Programmed cell death (PCD) is an active cellular suicide that occurs both in animals and plants throughout development and
in response to abiotic or biotic stress. In contrast to plant hypersensitive response-like cell death, little is known about
the molecular machinery that regulates the halophyte plant PCD under high salinity stress. Since mitogen-activated protein
kinases (MAPKs) are involved in plant response/tolerance to salt stress, and plant MAPK genes belong to the extracellular
signal-regulated kinase (ERK) subfamily, we have investigated the role of ERK-like enzymes in high salinity stress-induced
cell death in Thellungiella halophila. The data showed that ERK-like enzymes were early (10 min) and transiently activated under 300 mM NaCl stress. Pretreatment
with 10 μM U0126, a special MEK/ERK inhibitor, resulted in a small but statistically significant increase of the percentage
of terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL)-positive nuclei in contrast to salt alone.
The effects of U0126 on H2O2 production and cytochrome c (cyt c) release were also investigated. We found that the pretreatment with U0126 accelerated H2O2 production as well as cyt c release, and eventually enhanced cell death. The results suggest that ERK-like enzymes in Thellungiella halophila may act as a positive regulator of salt tolerance, as illustrated by pretreatment with U0126 which enhanced cell death under
high salinity stress. 相似文献
5.
Sharonov GV Feofanov AV Bocharova OV Astapova MV Dedukhova VI Chernyak BV Dolgikh DA Arseniev AS Skulachev VP Kirpichnikov MP 《Apoptosis : an international journal on programmed cell death》2005,10(4):797-808
A non-traumatic electroporation procedure was developed to load exogenous cytochrome c into the cytoplasm and to study the apoptotic effect of cytochrome c, its K72-substitued mutants and “yeast → horse” hybrid cytochrome c in living WEHI-3 cells. The minimum apoptosis-activating intracellular concentration of horse heart cytochrome c was estimated to be 2.7 ± 0.5 μM (47 ± 9 fg/cell). The equieffective concentrations of the K72A-, K72E- and K72L-substituted mutants of cytochrome c were five-, 15- and 70-fold higher. The “yeast → horse” hybrid created by introducing S2D, K4E, A7K, T8K, and K11V substitutions (horse protein numbering) and deleting five N-terminal residues in yeast cytochrome c did not evoke apoptotic activity in mammalian cells. The apoptotic function of cytochrome c was abolished by the K72W substitution. The K72W-substituted cytochrome c possesses reduced affinity to the apoptotic protease activating factor-1 (Apaf-1) and forms an inactive complex. This mutant is competent as a respiratory-chain electron carrier and well suited for knock-in studies of cytochrome c-mediated apoptosis. 相似文献
6.
Mitochondria,oxidative stress and cell death 总被引:4,自引:0,他引:4
Ott M Gogvadze V Orrenius S Zhivotovsky B 《Apoptosis : an international journal on programmed cell death》2007,12(5):913-922
In addition to the well-established role of the mitochondria in energy metabolism, regulation of cell death has recently emerged
as a second major function of these organelles. This, in turn, seems to be intimately linked to their role as the major intracellular
source of reactive oxygen species (ROS), which are mainly generated at Complex I and III of the respiratory chain. Excessive
ROS production can lead to oxidation of macromolecules and has been implicated in mtDNA mutations, ageing, and cell death.
Mitochondria-generated ROS play an important role in the release of cytochrome c and other pro-apoptotic proteins, which can trigger caspase activation and apoptosis. Cytochrome c release occurs by a two-step process that is initiated by the dissociation of the hemoprotein from its binding to cardiolipin,
which anchors it to the inner mitochondrial membrane. Oxidation of cardiolipin reduces cytochrome c binding and results in an increased level of “free” cytochrome c in the intermembrane space. Conversely, mitochondrial antioxidant enzymes protect from apoptosis. Hence, there is accumulating
evidence supporting a direct link between mitochondria, oxidative stress and cell death. 相似文献
7.
A detailed analysis of the periplasmic electron carriers of the photosynthetic bacterium Ectothiorhodospira sp. has been performed. Two low mid-point redox potential electron carriers, cytochrome c′ and cytochrome c, are detected. A high potential iron–sulfur protein is the only high mid-point redox potential electron transfer component
present in the periplasm. Analysis of light-induced absorption changes shows that this high potential iron–sulfur protein
acts in vivo as efficient electron donor to the photo-oxidized high potential heme of the Ectothiorhodospira sp. reaction center.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
Rapak A Stasik I Ziolo E Strzadala L 《Apoptosis : an international journal on programmed cell death》2007,12(10):1873-1878
Nur77 is reported to undergo translocation to mitochondria in response to apoptotic signaling in a variety of cancer cell
lines. It was shown that on the mitochondrial membrane, Nur77 interacts with Bcl-2, leading to the conversion of this protein
from a protector to a killer with subsequent release of cytochrome c to the cytosol. Here it is shown that in thymic lymphoma cells resistant to calcium-mediated apoptosis, cytochrome c release is abolished despite of Nur77 mitochondrial targeting. However, cytochrome c release and apoptosis can be restored by treatment with FK506. Hence, the molecular target regulation of the sensitivity
of lymphoma cells to calcium signaling is associated with cytochrome c release and is FK506 sensitive. These results provide new insight into the role of FK506-sensitive factors as a critical
link between calcium signaling and resistance of lymphoma cells to death. 相似文献
9.
Carlos A. Elena-Real Katiuska González-Arzola Gonzalo Pérez-Mejías Antonio Díaz-Quintana Adrián Velázquez-Campoy Bénédicte Desvoyes Crisanto Gutiérrez Miguel A. De la Rosa Irene Díaz-Moreno 《The Plant journal : for cell and molecular biology》2021,106(1):74-85
Programmed cell death (PCD) is crucial for development and homeostasis of all multicellular organisms. In human cells, the double role of extra-mitochondrial cytochrome c in triggering apoptosis and inhibiting survival pathways is well reported. In plants, however, the specific role of cytochrome c upon release from the mitochondria remains in part veiled yet death stimuli do trigger cytochrome c translocation as well. Here, we identify an Arabidopsis thaliana 14-3-3ι isoform as a cytosolic cytochrome c target and inhibitor of caspase-like activity. This finding establishes the 14-3-3ι protein as a relevant factor at the onset of plant H2O2-induced PCD. The in vivo and in vitro studies herein reported reveal that the interaction between cytochrome c and 14-3-3ι exhibits noticeable similarities with the complex formed by their human orthologues. Further analysis of the heterologous complexes between human and plant cytochrome c with plant 14-3-3ι and human 14-3-3ε isoforms corroborated common features. These results suggest that cytochrome c blocks p14-3-3ι so as to inhibit caspase-like proteases, which in turn promote cell death upon H2O2 treatment. Besides establishing common biochemical features between human and plant PCD, this work sheds light onto the signaling networks of plant cell death. 相似文献
10.
Bellyei S Szigeti A Boronkai A Pozsgai E Gomori E Melegh B Janaky T Bognar Z Hocsak E Sumegi B Gallyas F 《Apoptosis : an international journal on programmed cell death》2007,12(1):97-112
AlphaB-crystallin homology, heat stress induction and chaperone activity suggested that a previously encloned gene product
is a novel small heat shock protein (Hsp16.2). Suppression of Hsp16.2 by siRNA sensitized cells to hydrogen peroxide or taxol
induced cell-death. Over-expressing of Hsp16.2 protected cells against stress stimuli by inhibiting cytochrome c release from the mitochondria, nuclear translocation of AIF and endonuclease G, and caspase 3 activation. Recombinant Hsp16.2
protected mitochondrial membrane potential against calcium induced collapse in vitro indicating that Hsp16.2 stabilizes mitochondrial membrane systems. Hsp16.2 formed self-aggregates and bound to Hsp90. Inhibition
of Hsp90 by geldanamycin diminished the cytoprotective effect of Hsp16.2 indicating that this effect was Hsp90-mediated. Hsp16.2
over-expression increased lipid rafts formation as demonstrated by increased cell surface labeling with fluorescent cholera
toxin B, and increased Akt phosphorylation. The inhibition of PI-3-kinase—Akt pathway by LY-294002 or wortmannin significantly
decreased the protective effect of the Hsp16.2. These data indicate that the over-expression of Hsp16.2 inhibits cell death
via the stabilization of mitochondrial membrane system, activation of Hsp90, stabilization of lipid rafts and by the activation
of PI-3-kinase—Akt cytoprotective pathway. 相似文献
11.
Giulia Di Rocco Gianantonio Battistuzzi Carlo Augusto Bortolotti Marco Borsari Erika Ferrari Stefano Monari Marco Sola 《Journal of biological inorganic chemistry》2011,16(3):461-471
The 16-kDa diheme cytochrome c from the bacterium Shewanella baltica OS155 (Sb-DHC) was cloned and expressed in Escherichia coli and investigated through UV–vis, magnetic circular dichroism, and 1H NMR spectroscopies and protein voltammetry. The model structure was obtained by means of comparative modeling using the
X-ray structure of Rhodobacter sphaeroides diheme cytochrome c (Rs-DHC) (with a 37% pairwise sequence identity) as a template. Sb-DHC folds into two distinct domains, each containing one
heme center with a bis-His axial ligation. Both secondary and tertiary structures of the N-terminal domain resemble those
of class I cytochrome c, displaying three α-helices and a compact overall folding. The C-terminal domain is less helical than the corresponding domain
of Rs-DHC. The two heme groups are bridged by Tyr26 in correspondence with the shortest edge-to-edge distance, a feature which
would facilitate fast internal electron transfer. The electronic properties of the two prosthetic centers are equivalent and
sensitive to two acid–base equilibria with pK
a values of approximately 2.4 and 5, likely corresponding to protonation and detachment of the axial His ligands from the heme
iron and a pH-linked conformational change of the protein, respectively. Reduction potentials of −0.144 and −0.257 V (vs.
the standard hydrogen electrode), were determined for the C- and N-terminal heme groups, respectively. An approach based on
the extended Debye–Hückel equation was applied for the first time to a two-centered metalloprotein and was found to reproduce
successfully the ionic strength dependence of E°′. 相似文献
12.
Liu GY Liao YF Hsu PC Chang WH Hsieh MC Lin CY Hour TC Kao MC Tsay GJ Hung HC 《Apoptosis : an international journal on programmed cell death》2006,11(10):1773-1788
Antizymes delicately regulate ornithine decarboxylase (ODC) enzyme activity and polyamine transportation. One member of the
family, antizyme-1, plays vital roles in molecular and cellular functions, including developmental regulation, cell cycle,
proliferation, cell death, differentiation and tumorigenesis. However, the question of how does it participate in the cell
apoptotic mechanism is still unsolved. To elucidate the contribution of human antizyme-1 in haematopoietic cell death, we
examine whether inducible overexpression of antizyme enhances apoptotic cell death. Antizyme reduced the viability in a dose-
and time-dependent manner of human leukemia HL-60 cells, acute T leukemia Jurkat cells and mouse macrophage RAW 264.7 cells.
The apoptosis-inducing activities were determined by nuclear condensation, DNA fragmentation, sub-G1 appearance, loss of mitochondrial membrane potential (Δψ
m
), release of mitochondrial cytochrome c into cytoplasm and proteolytic activation of caspase 9 and 3. Following conditional antizyme overexpression, all protein
levels of cyclin-dependent kinases (Cdks) and cyclins are not significantly reduced, except cyclin D, before their entrance
into apoptotic cell death. However, introduced cyclin D1 into Jurkat T tetracycline (Tet)-On cell system still couldn’t rescue
cells from apoptosis. Antizyme doesn’t influence the expression of tumor suppressor p53 and its downstream p21, but it interferes
in the expressions of Bcl-2 family. Inducible antizyme largely enters mitochondria resulting in cytochrome c release from mitochondria to cytosol following Bcl-xL decrease and Bax increase. According to these data, we suggest that
antizyme induces apoptosis mainly through mitochondria-mediated and cell cycle-independent pathway. Furthermore, antizyme
induces apoptosis not only by Bax accumulation reducing the function of the Bcl-2 family, destroying the Δψ
m
, and releasing cytochrome c to cytoplasm but also by the activation of apoptosomal caspase cascade. 相似文献
13.
P. M. Paes de Sousa S. R. Pauleta M. L. Simões Gonçalves G. W. Pettigrew I. Moura M. M. Correia dos Santos J. J. G. Moura 《Journal of biological inorganic chemistry》2007,12(5):691-698
This work reports the direct electrochemistry of Paracoccus pantotrophus pseudoazurin and the mediated catalysis of cytochrome c peroxidase from the same organism. The voltammetric behaviour was examined at a gold membrane electrode, and the studies
were performed in the presence of calcium to enable the peroxidase activation. A formal reduction potential, E
0′, of 230 ± 5 mV was determined for pseudoazurin at pH 7.0. Its voltammetric signal presented a pH dependence, defined by
pK values of 6.5 and 10.5 in the oxidised state and 7.2 in the reduced state, and was constant up to 1 M NaCl. This small copper
protein was shown to be competent as an electron donor to cytochrome c peroxidase and the kinetics of intermolecular electron transfer was analysed. A second-order rate constant of 1.4 ± 0.2 × 105 M−1 s−1 was determined at 0 M NaCl. This parameter has a maximum at 0.3 M NaCl and is pH-independent between pH 5 and 9. 相似文献
14.
Complex structure of cytochrome c–cytochrome c oxidase reveals a novel protein–protein interaction mode 下载免费PDF全文
Satoru Shimada Kyoko Shinzawa‐Itoh Junpei Baba Shimpei Aoe Atsuhiro Shimada Eiki Yamashita Jiyoung Kang Masaru Tateno Shinya Yoshikawa Tomitake Tsukihara 《The EMBO journal》2017,36(3):291-300
Mitochondrial cytochrome c oxidase (CcO) transfers electrons from cytochrome c (Cyt.c) to O2 to generate H2O, a process coupled to proton pumping. To elucidate the mechanism of electron transfer, we determined the structure of the mammalian Cyt.c–CcO complex at 2.0‐Å resolution and identified an electron transfer pathway from Cyt.c to CcO. The specific interaction between Cyt.c and CcO is stabilized by a few electrostatic interactions between side chains within a small contact surface area. Between the two proteins are three water layers with a long inter‐molecular span, one of which lies between the other two layers without significant direct interaction with either protein. Cyt.c undergoes large structural fluctuations, using the interacting regions with CcO as a fulcrum. These features of the protein–protein interaction at the docking interface represent the first known example of a new class of protein–protein interaction, which we term “soft and specific”. This interaction is likely to contribute to the rapid association/dissociation of the Cyt.c–CcO complex, which facilitates the sequential supply of four electrons for the O2 reduction reaction. 相似文献
15.
Toshihede Matsuno Kazuaki Yoshimune Isao Yumoto 《Journal of bioenergetics and biomembranes》2011,43(5):473-481
It has been found that the alkaliphilic Gram-negative bacterium Pseudomonas alcaliphila AL15-21T produces a larger amount of soluble c-type cytochromes at pH 10.0 under air-limited condition than at pH 7.0 under high aeration. Cytochrome c-552 was confirmed as the major c-type cytochrome among three soluble c-type cytochromes in the strain. To understand the physiological function of cytochrome c-552, a P. alcaliphila AL15-21T cytochrome c-552 gene deletion mutant without a marker gene was constructed by electrotransformation adjusted in this study for the strain.
The maximum specific growth rate and maximum cell turbidity of cells grown at pHs 7.0 and 10.0 under the high-aeration condition
did not differ significantly between the wild-type and cytochrome c-552 deletion mutant strains. In the mutant grown at pH 10.0 under low-aeration condition, marked decreases in the maximum
specific growth rate (40%) and maximum cell turbidity (25%) compared with the wild type were observed. On the other hand,
the oxygen consumption rates of cell suspensions of the mutant obtained by the growth at pH 10 under low-aeration condition
were slightly higher than that of the wild type. Considering the high electron-retaining ability of cytochrome c-552, the above observations could be accounted for by cytochrome c-552 acting as an electron sink in the periplasmic space. This may facilitate terminal oxidation in the respiratory system
at high pH under air-limited conditions. 相似文献
16.
Chamorovsky SK Chamorovsky CS Knox PP Chizhov IV Zubov BV 《European biophysics journal : EBJ》2007,36(6):601-608
Laser-induced temperature jump experiments were used for testing the rates of thermoinduced conformational transitions of
reaction center (RC) complexes in chromatophores of Chromatium minutissimum. The thermoinduced transition of the macromolecular RC complex to a state providing effective electron transport from the
multiheme cytochrome c to the photoactive bacteriochlorophyll dimer within the temperature range 220–280 K accounts for tens of seconds with activation
energy 0.166 eV/molecule. The rate of the thermoinduced transition in the cytochrome–RC complex was found to be three orders
of magnitude slower than the rate of similar thermoinduced transition of the electron transfer reaction from the primary to
secondary quinone acceptors studied in the preceding work (Chamorovsky et al. in Eur Biophys J 32:537–543, 2003). Parameters of thermoinduced activation of the electron transfer from the multiheme cytochrome c to the photoactive bacteriochlorophyll dimer are discussed in terms of cytochrome c docking onto the RC. 相似文献
17.
Ivano Bertini Gabriele Cavallaro Antonio Rosato 《Journal of biological inorganic chemistry》2005,10(6):613-624
An ensemble of structural models of the adduct between cytochrome c and cytochrome c oxidase from Paracoccus denitrificans has been calculated based on the experimental data from site-directed mutagenesis and NMR experiments that have accumulated
over the last years of research on this system. The residues from each protein that are at the protein–protein interface have
been identified by the above experimental work, and this information has been converted in a series of restraints explicitly
used in calculations. It is found that a single static structural model cannot satisfy all experimental data simultaneously.
Therefore, it is proposed that the adduct exists as a dynamic ensemble of different orientations in equilibrium, and may be
represented by a combination or average of the various limiting conformations calculated here. The equilibrium involves both
conformations that are competent for electron transfer and conformations that are not. Long-range recognition of the partners
is driven by non-specific electrostatic interactions, while at shorter distances hydrophobic contacts tune the reciprocal
orientation. Electron transfer from cytochrome bc
1 to cytochrome c oxidase is mediated through cytochrome c experiencing multiple encounters with both of its partners, only part of which are productive. The number of encounters,
and thus the electron transfer rate, may be increased by the formation of a cytochrome bc
1–cytochrome c oxidase supercomplex and/or (in human) by increasing the concentration of the two enzymes in the membrane space.
Protein Data Bank Accession numbers The coordinates of the five best structural models for each of the four clusters have been deposited in the Protein Data Bank
(PDB ID 1ZYY). 相似文献
18.
Badri S. Rajagopal Michael T. Wilson Derek S. Bendall Christopher J. Howe Jonathan A. R. Worrall 《Journal of biological inorganic chemistry》2011,16(4):577-588
The amino acid at position 51 in the cytochrome c
6 family is responsible for modulating over 100 mV of heme midpoint redox potential. As part of the present work, the X-ray
structure of the imidazole adduct of the photosynthetic cytochrome c
6 Q51V variant from Phormidium laminosum has been determined. The structure reveals the axial Met ligand is dissociated from the heme iron but remains inside the
heme pocket and the Ω-loop housing the Met ligand is stabilized through polar interactions with the imidazole and heme propionate-6.
The latter is possible owing to a 180° rotation of both heme propionates upon imidazole binding. From equilibrium and kinetic
studies, a Val residue at position 51 increases the stability of the Fe–S(Met) interaction and also affects the dynamics associated
with imidazole binding. In this respect, the k
obs for imidazole binding to Arabidopsis thaliana cytochrome c
6A, which has a Val at the position equivalent to position 51 in photosynthetic cytochrome c
6, was found to be independent of imidazole concentration, indicating that the binding process is limited by the Met dissociation
rate constant (about 1 s−1). For the cytochrome c
6 Q51V variant, imidazole binding was suppressed in comparison with the wild-type protein and the V52Q variant of cytochrome
c
6A was found to bind imidazole readily. We conclude that the residue type at position 51/52 in the cytochrome c
6 family is additionally responsible for tuning the stability of the heme iron–Met bond and the dynamic properties of the ferric
protein fold associated with endogenous ligand binding. 相似文献
19.
Roberto E. Di Paolo Patrícia M. Pereira Inês Gomes Filipa M. A. Valente Inês A. C. Pereira Ricardo Franco 《Journal of biological inorganic chemistry》2006,11(2):217-224
Resonance Raman (RR) spectroscopy was used to investigate conformational characteristics of the hemes of several ferricytochromes
of the cytochrome c
3 family, electron transfer proteins isolated from the periplasm and membranes of sulfate-reducing bacteria. Our analysis concentrated
on the low-frequency region of the RR spectra, a fingerprint region that includes vibrations for heme-protein C–S bonds [ν(CaS)]. It has been proposed that these bonds are directly involved in the electron transfer process. The three groups of tetraheme
cytochrome c
3 analyzed, namely Type I cytochrome c
3 (TpIc
3s), Type II cytochrome c
3 (TpIIc
3s) and Desulfomicrobium cytochromes c
3, display different frequency separations for the two ν(CaS) lines that are similar among members of each group. These spectral differences correlate with differences in protein structure
observed among the three groups of cytochromes c
3. Two larger cytochromes of the cytochrome c
3 family display RR spectral characteristics for the ν(CaS) lines that are closer to TpIIc
3 than to TpIc
3. Two other multiheme cytochromes from Desulfovibrio that do not belong to the cytochrome c
3 family display ν(CaS) lines with reverse relative areas in comparison with the latter family. This RR study shows that the small differences
in protein structure observed among these cytochrome c
3 correlate to differences on the heme–protein bonds, which are likely to have an impact upon the protein function, making
RR spectroscopy a sensitive and useful tool for characterizing these cytochromes. 相似文献
20.
Díaz-Quintana A Navarro JA Hervás M Molina-Heredia FP De la Cerda B De la Rosa MA 《Photosynthesis research》2003,75(2):97-110
Plastocyanin and cytochrome c
6 are two soluble metalloproteins that act as alternative electron carriers between the membrane-embedded complexes cytochromes
b
6
f and Photosystem I. Despite plastocyanin and cytochrome c
6 differing in the nature of their redox center (one is a copper protein, the other is a heme protein) and folding pattern
(one is a β-barrel, the other consists of α-helices), they are exchangeable in green algae and cyanobacteria. In fact, the
two proteins share a number of structural similarities that allow them to interact with the same membrane complexes in a similar
way. The kinetic and thermodynamic analysis of Photosystem I reduction by plastocyanin and cytochrome c
6 reveals that the same factors govern the reaction mechanism within the same organism, but differ from one another. In cyanobacteria,
in particular, the electrostatic and hydrophobic interactions between Photosystem I and its electron donors have been analyzed
using the wild-type protein species and site-directed mutants. A number of residues similarly conserved in the two proteins
have been shown to be critical for the electron transfer reaction. Cytochrome c
6 does contain two functional areas that are equivalent to those previously described in plastocyanin: one is a hydrophobic
patch for electron transfer (site 1), and the other is an electrically charged area for complex formation (site 2). Each cyanobacterial
protein contains just one arginyl residue, similarly located between sites 1 and 2, that is essential for the redox interaction
with Photosystem I.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献