共查询到20条相似文献,搜索用时 31 毫秒
1.
Masaya Kitamura Kazuya Mizugai Masahiro Taniguchi Hideo Akutsu Izumi Kumagai Tadao Nakaya 《Microbiology and immunology》1995,39(1):75-80
The gene encoding cytochrome c-553 from Desulfovibrio vulgaris (Miyazaki F) was cloned using a synthetic oligodeoxyribonucleotide probe. The nucleotide sequence indicated that cytochrome c-553 was synthesized as a precursor protein with an NH2-terminal signal sequence of 23 residues. In the cloned DNA fragment, there are three other open reading frames whose products have 191, 157, 541 amino acid residues, respectively. The putative ORF-4 product is highly homologous with the cytochrome c oxidase subunit I from various organisms. 相似文献
2.
An efficient method for the preparation of isotopically enriched heme has been developed. This method utilizes a commercially available bacterial host and plasmid, into which a synthetic gene encoding for rat liver outer mitochondrial membrane cytochrome b5 a heme-binding protein, has been inserted. The method described in this report utilizes the efficient synthesis of the cytochrome b5 polypeptide together with the enhanced biosynthesis of heme brought about by addition of the first committed precursor in heme biosynthesis, δ-aminolevulinic acid. Apocytochrome b5 sequesters heme as the macrocycle is being synthesized in order to form holocytochrome b5, thus avoiding toxic concentrations of free macrocycle in the cell. Relatively high concentrations of free heme in the cell have been shown to stimulate excretion of heme precursors such as coproporphyrinogen and uroporphyrinogen (W. F. Harris III, R. S. Burkhalter, W. Lin and R. Timkovich, (1993) Bioorg. Chem. 21, 209-220), therefore causing isotopic dilution of the labeled material. The heme obtained using this methodology was determined to be >85% enriched. Because the heme in cytochrome b5 is not covalently attached to the polypeptide, it can be extracted and used in other applications. Use of glutamate, a precursor of δ-aminolevulinate biosynthesis in Escherichia coli, did not result in high levels of isotopic incorporation into heme, thus pointing out to the importance of using a labeled precursor that is committed to heme biosynthesis in order to obtain high levels of isotopic labeling. 相似文献
3.
J. Steppuhn C. Rother J. Hermans T. Jansen J. Salnikow G. Hauska R. G. Herrmann 《Molecular & general genetics : MGG》1987,210(1):171-177
Summary SummarySeveral cDNA clones encoding the entire Rieske FeS-precursor protein of the chloroplast cytochrome b
6
f-complex have been isolated by high density plaque immunoscreening of a phage lambda gt11 cDNA expression library, made from poly A+-RNA of spinach seedlings. The identity of the cDNAs has been confirmed by N-terminal amino acid sequencing of the purified protein. The nucleotide sequence indicates a protein of 247 amino acid residues including a putative transit sequence of 68 amino acids corresponding to molecular masses of 26.3 kDa (precursor) and 18.8 kDa (mature protein; 179 amino acid residues). Alignteins of the sequence with sequences from Rieske FeS-proteins of respiratory electron transport chains, two of bacterial and three of mitochondrial origin, shows little sequence homology, but remarkable similarity in secondary structure including a putative N-terminal transmembrane segment of about 25 residues and the peptides CTHLGCV and CPCHGS in the C-terminal region of the protein that are involved in the binding of the Fe2S2-cluster. 相似文献
4.
The molecular organization of the lysostaphin gene and its sequences repeated in tandem 总被引:10,自引:0,他引:10
Peter Heinrich Ralf Rosenstein Maria Böhmer Peter Sonner Friedrich Götz 《Molecular & general genetics : MGG》1987,209(3):563-569
Summary The gene encoding lysostaphin of Staphylococcus staphylolyticus was cloned in Escherichia coli and its DNA sequence was determined. The complete coding region comprises 1440 base pairs corresponding to a precursor of 480 amino acids (molecular weight 51669). It was shown by NH2-terminal amino acid sequence analysis of the purified extracellular lysostaphin from S. staphylolyticus that the mature lysostaphin consists of 246 amino acid residues (molecular weight 26926). Polyacrylamide gel electrophoresis revealed a similar molecular weight for the most active form. By computer analysis the secondary protein structure was predicted. It revealed three distinct regions in the precursor protein: a typical signal peptide (ca. 38 aa), a hydrophilic and highly ordered protein domain with 14 repetitive sequences (296 aa) and the hydrophobic mature lysostaphin. The lysostaphin precursor protein appears to be organized as a preprolysostaphin.Abbreviations aa
amino acid(s) 相似文献
5.
J. Hermans Ch. Rother J. Bichler J. Steppuhn R. G. Herrmann 《Plant molecular biology》1988,10(4):323-330
The nucleotide sequence of the entire nuclear-encoded precursor for subunit delta of the ATP synthase from spinach thylakoid membranes was determined by cDNA sequencing. Appropriate recombinant DNAs were selected from pBR322 and lambda gt11 libraries made from polyadenylated RNA of greening spinach seedlings. The mature protein consists of 187 amino acid residues corresponding to a molecular weight of 20468. The precursor protein (257 amino acid residues; M
r=27676) is probably processed between a Met-Val bond. The predicted secondary structure of the transit sequence (70 residues; 7.2 kDa) resembles that of the Rieske Fe/S polypeptide, but shows little similarity with those of stromal or luminal proteins. The comparison of the chloroplast delta amino acid sequence with the published delta sequences from respiratory ATP synthases of bacterial and mitochondrial sources and from the thylakoid ATP synthase of the cyanobacterium Synechococcus suggests substantial divergence at the genic level although structural elements appear to be remarkably conserved. 相似文献
6.
Marie Hugosson Ghasem Nurani Elzbieta Glaser Lars-Gunnar Franzén 《Plant molecular biology》1995,28(3):525-535
It has previously been shown that presequences of nuclear-encoded chloroplast proteins from the green alga Chlamydomonas reinhardtii contain a region that may form an amphiphilic -helix, a structure characteristic of mitochondrial presequences. We have tested two precursors of chloroplast proteins (the PsaF and PsaK photosystem I subunits) from C. reinhardtii for the ability to be imported into spinach leaf mitochondria in vitro. Both precursors bound to spinach mitochondria. The PsaF protein was converted into a protease-protected form with high efficiency in a membrane potential-dependent manner, indicating that the protein had been imported, whereas the PsaK protein was not protease protected. The protease protection of PsaF was not inhibited by a synthetic peptide derived from the presequence of the N. plumbaginifolia mitochondrial F1 subunit. Furthermore, if the presequence of PsaF was truncated or deleted by in vitro mutagenesis, the protein was still protease-protected with approximately the same efficiency as the full-length precursor. These results indicate that PsaF can be imported by spinach mitochondria in a presequence-independent manner. However, even in the absence of the presequence, this process was membrane potential-dependent. Interestingly, the presequence-truncated PsaF proteins were also protease-protected upon incubation with C. reinhardtii chloroplasts. Our results indicate that the C. reinhardtii chloroplast PsaF protein has peculiar properties and may be imported not only into chloroplasts but also into higher-plant mitochondria. This finding indicates that additional control mechanisms in the cytosol that are independent of the presequence are required to achieve sorting between chloroplasts and mitochondria in vivo.Abbreviations cTP
chloroplast transit peptide
- mTP
mitochondrial targeting peptide
- Rubisco
ribulose-1,5-bisphosphate carboxylase/oxygenase
- pF1(1,25)
a synthetic peptide derived from the first 25 residues of the Nicotiana plumbaginifolia mitochondrial ATP synthase F1 subunit
- PsaF(2–30) and PsaF(2–61)
mutant proteins lacking regions corresponding to residues 2–30 and 2–61 in the PsaF precursor protein, respectively 相似文献
7.
Vasanthakumar P. Rajappan Ramachandra S. Hosmane 《Nucleosides, nucleotides & nucleic acids》2013,32(7):1141-1151
Abstract Synthesis and biochemical screening against guanase of analogues of the naturally occurring guanase inhibitor azepinomycin (2) are reported. Compound e-amino-5,6,7,8,-tetrahydro-4H-imidazo[4,5-e][1,4]diazepine-5,8-dione (3) was synthesized in six steps commencing with 1-benzyl-5-nitroimidazole-4-carboxylic acid (5). Compound 3 and its synthetic precursor 3-benzyl-6-(N-benzyloxycarbonyl)amino-5,6,7,8-tetrahydro-4H-imidazo[4,5-e][1,4]diazepine-5,8-dione (12) were screened against rabbit liver guanase. Both were found to be moderate inhibitors of the enzyme with K1′s in the range of 10?4 M. 相似文献
8.
We report the isolation and characterization of a recombinant cDNA phage from a lambda gt11 expression library made from polyadenylated spinach RNA that encodes the entire precursor polypeptide of ferredoxin I. The deduced sequence predicts a molecular mass of 10.5 kDa (97 amino acid residues) for the mature protein and a transit peptide of 50 residues (5.2 kDa). In vitro synthesized ferredoxin precursor was used for import experiments with isolated unbroken spinach chloroplasts. The polypeptide was correctly directed to the organelle stroma and processed to the size of the mature protein. Northern analysis indicates a mRNA size of ca. 850 nucleotides which is close to the size of the cDNA insert (ca. 700 bp). 相似文献
9.
Jun Matsui Junji Nagano Daisuke Miyoshi Katsuyuki Tamaki Naoki Sugimoto 《Biosensors & bioelectronics》2009,25(3):563
Random selection, rational design and molecular imprinting were cooperatively utilized to develop peptide-based ATP synthetic receptors. In this fusion strategy, combinatorial chemistry was utilized for screening a precursor peptide useful for construction of ATP receptors, and rational design was employed in modification of the selected precursor peptide for higher affinity and selectivity. Finally, molecular imprinting was used for pre-organizing the conformation of the precursor peptide as complementary to a target molecule ATP. The fusion strategy appeared to have advantage to sole use of the individual strategy: (1) a low hit-rate of combinatorial chemistry will be improved by customizing a higher order structure of a selected peptide by molecular imprinting, (2) combinatorial chemistry allows us to semi-automatically select components of water-compatible synthetic receptors, (3) rational design improves the selected peptide sequence for better molecularly imprinted receptors.A peptide consisting of a randomly selected sequence and a rationally designed sequence (Resin-Lys-Gly-Arg-Gly-Lys-Gly-Gly-Gly-Glu-Lys-Tyr-Leu-Lys-NHAc) was designed and synthesized as a precursor peptide. The rational design was made according to the sequence of the adenine binding site of biotin carboxylase. The on-beads peptide was cross-linked with dimethyl adipimidate in the presence of ATP. In the saturation binding tests, the cross-linked on-beads peptide showed 5.3 times higher affinity compared to the non-cross-linked peptide with the same sequence. Furthermore, the cross-linked peptide showed improved selectivity; the ratios of binding constants, K(ATP)/K(ADP) and K(ATP)/K(GTP), were increased from 2.4 to 19, and from 0.8 to 10, respectively. It would be notable that the peptide without the rationally designed sequence showed no discrimination between ATP and GTP (K(ATP)/K(GTP) as 0.9), suggesting that the rationally designed site was successfully engaged for recognition of the adenine base. 相似文献
10.
11.
Signal Peptide and Propeptide Optimization for Heterologous Protein Secretion in Lactococcus lactis 总被引:4,自引:0,他引:4
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Y. Le Loir S. Nouaille J. Commissaire L. Brtigny A. Gruss P. Langella 《Applied microbiology》2001,67(9):4119-4127
Lactic acid bacteria are food-grade microorganisms that are potentially good candidates for production of heterologous proteins of therapeutical or technological interest. We developed a model for heterologous protein secretion in Lactococcus lactis using the staphylococcal nuclease (Nuc). The effects on protein secretion of alterations in either (i) signal peptide or (ii) propeptide sequences were examined. (i) Replacement of the native Nuc signal peptide (SPNuc) by that of L. lactis protein Usp45 (SPUsp) resulted in greatly improved secretion efficiency (SE). Pulse-chase experiments showed that Nuc secretion kinetics was better when directed by SPUsp than when directed by SPNuc. This SPUsp effect on Nuc secretion is not due to a better antifolding activity, since SPUsp:Nuc precursor proteins display enzymatic activity in vitro, while SPNuc:Nuc precursor proteins do not. (ii) Deletion of the native Nuc propeptide dramatically reduces Nuc SE, regardless of which SP is used. We previously reported that a synthetic propeptide, LEISSTCDA, could efficiently replace the native Nuc propeptide to promote heterologous protein secretion in L. lactis (Y. Le Loir, A. Gruss, S. D. Ehrlich, and P. Langella, J. Bacteriol. 180:1895–1903, 1998). To determine whether the LEISSTCDA effect is due to its acidic residues, specific substitutions were introduced, resulting in neutral or basic propeptides. Effects of these two new propeptides and of a different acidic synthetic propeptide were tested. Acidic and neutral propeptides were equally effective in enhancing Nuc SE and also increased Nuc yields. In contrast, the basic propeptide strongly reduced both SE and the quantity of secreted Nuc. We have shown that the combination of the native SPUsp and a neutral or acidic synthetic propeptide leads to a significant improvement in SE and in the quantity of synthesized Nuc. These observations will be valuable in the production of heterologous proteins in L. lactis. 相似文献
12.
Signal peptide mutants ofEscherichia coli 总被引:10,自引:0,他引:10
Joseph Gennity Joel Goldstein Masayori Inouye 《Journal of bioenergetics and biomembranes》1990,22(3):233-269
Numerous secretory proteins of the Gram-negative bacteriaE. coli are synthesized as precursor proteins which require an amino terminal extension known as the signal peptide for translocation across the cytoplasmic membrane. Following translocation, the signal peptide is proteolytically cleaved from the precursor to produce the mature exported protein. Signal peptides do not exhibit sequence homology, but invariably share common structural features: (1) The basic amino acid residues positioned at the amino terminus of the signal peptide are probably involved in precursor protein binding to the cytoplasmic membrane surface. (2) A stretch of 10 to 15 nonpolar amino acid residues form a hydrophobic core in the signal peptide which can insert into the lipid bilayer. (3) Small residues capable of -turn formation are located at the cleavage site in the carboxyl terminus of the signal peptide. (4) Charge characteristics of the amino terminal region of the mature protein can also influence precursor protein export. A variety of mutations in each of the structurally distinct regions of the signal peptide have been constructedvia site-directed mutagenesis or isolated through genetic selection. These mutants have shed considerable light on the structure and function of the signal peptide and are reviewed here. 相似文献
13.
The hydABC operon of Wolinella succinogenes encodes the three subunits of the membrane-integrated Ni-hydrogenase. The catalytic subunit, HydB, is on the periplasmic
side of the membrane. Residues R41 and R42 of the twin-arginine motif within the signal peptide of the precursor of the iron-sulfur
subunit, HydA, were replaced by two glutamine residues. The corresponding mutant did not grow with H2 as the electron donor of anaerobic respiration. Mature HydB and the precursor protein of HydA were located exclusively in
the cytoplasmic cell fraction of the mutant, which catalyzed the reduction of benzyl viologen by H2, suggesting that HydB contained Ni. The HydC protein was located in the membrane fraction of the mutant in wild-type amounts.
HydC was purified and was shown to contain heme. The results suggest that HydA and HydB are translocated across the membrane
by the Tat (twin-arginine translocation) system. The translocation of HydA and HydB as well as the maturation of the precursor
protein of HydA appear to depend on the presence of the twin-arginine motif. In contrast, maturation of HydB, the insertion
of HydC into the membrane, and heme attachment to HydC are apparently independent of the twin-arginine motif and do not require
translocation of the two other hydrogenase subunits.
Received: 17 June 1999 / Accepted: 21 July 1999 相似文献
14.
Cloning and sequence analysis of a cDNA encoding a Brazil nut protein exceptionally rich in methionine 总被引:2,自引:0,他引:2
Susan B. Altenbach Karen W. Pearson Filomena W. Leung Samuel S. M. Sun 《Plant molecular biology》1987,8(3):239-250
The primary amino acid sequence of an abundant methionine-rich seed protein found in Brazil nut (Bertholletia excelsa H.B.K.) has been elucidated by protein sequencing and from the nucleotide sequence of cDNA clones. The 9 kDa subunit of this protein was found to contain 77 amino acids of which 14 were methionine (18%) and 6 were cysteine (8%). Over half of the methionine residues in this subunit are clustered in two regions of the polypeptide where they are interspersed with arginine residues. In one of these regions, methionine residues account for 5 out of 6 amino acids and four of these methionine residues are contiguous. The sequence data verifies that the Brazil nut sulfur-rich protein is synthesized as a precursor polypeptide that is considerably larger than either of the two subunits of the mature protein. Three proteolytic processing steps by which the encoded polypeptide is sequentially trimmed to the 9 kDa and 3 kDa subunit polypeptides have been correlated with the sequence information. In addition, we have found that the sulfur-rich protein from Brazil nut is homologous in its amino acid sequence to small water-soluble proteins found in two other oilseeds, castor bean (Ricinus communis) and rapeseed (Brassica napus). When the amino acid sequences of these three proteins are aligned to maximize homology, the arrangement of cysteine residues is conserved. However, the two subunits of the Brazil nut protein contain over 19% methionine whereas the homologous proteins from castor bean and rapeseed contain only 2.1% and 2.6% methionine, respectively. 相似文献
15.
Hashizume F Hino S Kakehashi M Okajima T Nadano D Aoki N Matsuda T 《Transgenic research》2008,17(6):1117-1129
Type II collagen (CII) in joint cartilage is known to be a major auto-antigen in human rheumatoid arthritis. Several animal
model- and clinical-studies on tolerance-based immunotherapy for the arthritis have been conducted by administrating synthetic
immunodominant peptides through an oral route. In the present study, to produce a tolerogenic peptide with therapeutic potential
in transgenic rice plants, a gene construct producing glutelin fusion protein with tandem four repeats of a CII250–270 peptide (residues 250–270) (GluA-4XCII250–270) containing a human T-cell epitope was introduced with a selection marker, hygromycin phosphotransferase gene (hygromycin-resistance
gene) (hph), by co-transformation. Several transgenic plants with high and stable expression of gluA-4XCII
250–270
, but no hph, were selected based on both DNA and protein analyses. The GluA-4XCII250–270 fusion proteins were detected as both precursor and processed forms mainly in a glutelin fraction of rice endosperm protein
extracts and in protein-body rich fractions prepared by density gradient ultracentrifugation. The amount of accumulated CII250–270 peptide was immunochemically estimated to be about 1 μg per seed. Feeding DBA/1 mice the transgenic rice seeds (25 μg of
the peptide per mouse a day) for 2 weeks showed tendencies lowering and delaying serum specific-IgG2a response against subsequent
and repeated intraperitoneal-injection of type II collagen. Taken these together, the CII-immunodominant peptide could effectively
be produced and accumulated as a glutelin-fusion protein in the transgenic rice seeds, which might be useful as pharmaceutical
materials and functional food for prevention and therapy for anti-CII autoimmune diseases like human rheumatoid arthritis. 相似文献
16.
J W Suttie S R Lehrman L O Geweke J M Hageman D H Rich 《Biochemical and biophysical research communications》1979,86(3):500-507
Rat liver microsomes contain a triton X-100 solubilizable vitamin K-dependent carboxylase activity that converts specific glutamyl residues of precursor proteins to γ-carboxyglutamyl residues. This activity has been studied utilizing synthetic peptides as substrates for the enzyme. When compared to the carboxylation of the endogenous microsomal precursors, the peptide carboxylase activity is more sensitive to the action of various inhibitors, and requires a higher concentration of vitamin K for maximal activity. The apparent Km for the peptide Phe-Leu-Glu-Glu-Leu was found to be 4 mM. Substrate specificity depends on residues adjacent to the carboxylated Glu residues and macromolecular recognition sites. 相似文献
17.
Jun-ling You Saskia C. F. Milton Raymond C. deLisle Milton N. S. Rangaraju Robert B. Harris 《Journal of Protein Chemistry》1993,12(2):133-141
Homogeneous pre-pro-GnRH/GAP protein was recently synthesized in 100 mg quantities by solid-phase methods and surprisingly, the synthetic pre-pro-protein, which normally does not escape the endoplasmic recticulum, was found to inhibit the release of prolactin from cultured pituitary cells. This is the first demonstration of significant biological activity associated with a precursor protein and provides the rationale for its further study. We now report the results of our initial examination of the conformational properties of pre-pro-GnRH/GAP protein as a prelude to solving its solution phase conformation by homonuclear1H-NMR protocols. Thermal andpH titration fluorescence and circular dichroism spectroscopies reveal that the protein is resistant to thermal-induced conformational changes but is particularly sensitive topH-induced conformational changes; while Asp/Glu and Arg residues may contribute to structural stability, His and Lys residues predominate. Pre-pro-GnRH/GAP is about 30% helix in the range of 2–40°C; however, even at 90°C, the peptide retains nearly 50% of its helix character. There is no evidence for a cooperative transition; for this reason, differential scanning calorimetry failed to yield a defined transition thermogram. Pre-pro-GnRH/GAP apparently does not pass through a transition state as a function of temperature but appears to flex and retain a high percentage of helix structure, resulting in subtle changes in secondary structure. There is no discernible isodichroic point. On either side of the neutralpH range, however, there are dramatic changes in structure that result in nonreversible denaturation of the protein. Relative to N(Ac)Trp-amide, the emission position of intrinsic Trp fluorescence of pre-pro-GnRH/GAP is blue shifted to 338 nm, indicating that the microenvironment(s) encompassing the 2 Trp residues are buried within the protein structure. Synthetic pre-pro-GNRH/GAP is a substrate for GAP-releasing enzyme (the proposed physiologically relevant processing enzyme of the precursor protein) and yields GAP peptide (D14–I69). Of the other serine proteinases tested (trypsin, plasmin, kallikrein), only GAP-releasing enzyme shows this specificity of cleavage. Hierarchical cleavage observed in the time course of proteolysis with trypsin, however, suggests that other peptide products might be formed from GAP once it is processed from the precursor protein by cleavage at sites other than the primary processing site catalyzed by enzymes other than GAP-releasing enzyme. The primary processing site for GAP-releasing enzyme (GLRPGGKR) is thus accessible in the precursor protein, consistent with our hypothesis that the recognition sequence is located at the surface of the protein and acts as a recognition element for the processing endoproteinase. The conformation of the precursor protein is dynamic, supporting the idea that intracellular (and/or intragranular) conditions may play a role in regulation of endoproteolysis. Conformational flexing of the pro-hormone in response to intracellular conditions may serve to differentially expose various processing sites which may help explain tissue specificity of processing. 相似文献
18.
Bombesin and its receptors have been demonstrated to be involved in a larger array of physiological and pathophysiological
conditions including memory and fear behavior, lung development and injury, and tumor growth. A bombesin-like peptide named
bombesin-RS was purified and characterized from the skin secretions of the frog, Rana shuchinae. Its amino acid sequence (pETSFMAPSWALGHLM-NH2) was determined by auto Edman degradation and mass spectrometry. The cDNA encoding bombesin-RS precursor was cloned from
skin cDNA library of this frog. The precursor is composed of 67 amino acid residues including a copy of mature bombesin-RS.
Two predicted enzymatic processing sites (-Lys-Lys- and -Lys-Arg-) are flanked at the mature bombesin-RS sequence. In the
in vitro myotropic contraction experiment, the synthesized bombesin-RS displayed stimulating effect toward rat stomach strips,
suggesting that bombesin-RS acts as agonist as most other bombesin-related peptides do. 相似文献
19.
Ana Kolarević Budimir S. Ilić Gordana Kocić Zdravko Džambaski Andrija Šmelcerović Bojan P. Bondžić 《Journal of cellular biochemistry》2019,120(1):264-274
Twelve new thiazolidinones were synthesized and, together with 41 previously synthesized thiazolidinones, evaluated for inhibitory activity against deoxyribonuclease I (DNase I) in vitro. Ten compounds inhibited commercial bovine pancreatic DNase I with an IC50 below 200 μM and showed to be more potent DNase I inhibitors than crystal violet (IC50 = 365.90 ± 47.33 μM), used as a positive control. Moreover, three compounds were active against DNase I in rat liver homogenate, having an IC50 below 200 μM. (3-Methyl-1,4-dioxothiazolidin-2-ylidene)-N-(2-phenylethyl)ethanamide ( 41 ) exhibited the most potent DNase I inhibition against both commercial and rat liver DNase I with IC50 values of 115.96 ± 11.70 and 151.36 ± 15.85 μM, respectively. Site Finder and molecular docking defined the thiazolidinones interactions with the most important catalytic residues of DNase I, including the H-acceptor interaction with residues His 134 and His 252 and/or H-donor interaction with residues Glu 39 and Asp 168. The three most active compounds against both commercial and rat liver DNase I ( 31 , 38 , and 41 ) exhibited favorable physico-chemical, pharmacokinetic, and toxicological properties. These observations could be utilized to guide the rational design and optimization of novel thiazolidinone inhibitors. Thiazolidinones as novel DNase I inhibitors could have potential therapeutic applications due to the significant involvement of DNase I in the pathophysiology of many disease conditions. 相似文献
20.
Roland Freudl Gabi Braun Ingrid Hindennach Ulf Henning 《Molecular & general genetics : MGG》1985,201(1):76-81
Summary The gene ompA encodes a major outer membrane protein of Escherichia coli. Localized mutagenesis of the part of the gene corresponding to the 21-residue signal sequence and the first 45 residues of the protein resulted in alterations which caused cell lysis when expressed. DNA sequence analyses revealed that in one mutant type the last CO2H-terminal residue of the signal sequence, alanine, was replaced by valine. The proteolytic removal of the signal peptide was much delayed and most of the unprocessed precursor protein was fractioned with the outer membrane. However, this precursor was completely soluble in sodium lauryl sarcosinate which does not solubilize the OmpA protein or fragments thereof present in the outer membrane. Synthesis of the mutant protein did not inhibit processing of the OmpA or OmpF proteins. In the other mutant type, multiple mutational alterations had occurred leading to four amino acid substitutions in the signal sequence and two affecting the first two residues of the mature protein. A reduced rate of processing could not be clearly demonstrated. Membrane fractionation suggested that small amounts of this precursor were associated with the plasma membrane but synthesis of this mutant protein also did not inhibit processing of the wild-type OmpA or OmpF proteins. Several lines of evidence left no doubt that the mature, mutant protein is stably incorporated into the outer membrane. It is suggested that the presence, in the outer membrane, of the mutant precursor protein in the former case, or of the mutant protein in the latter case perturbs the membrane architecture enough to cause cell death. 相似文献