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131.
The small heat-shock chaperone protein, alpha-crystallin, does not recognize stable molten globule states of cytosolic proteins 总被引:2,自引:0,他引:2
The small heat-shock protein (sHsp), alpha-crystallin, acts as a molecular chaperone by interacting with destabilized 'substrate' proteins to prevent their precipitation from solution under conditions of stress. alpha-Crystallin and all sHsps are intracellular proteins. Similarly to other chaperones, the 'substrate' protein is in an intermediately folded, partly structured molten globule state when it interacts and complexes with alpha-crystallin. In this study, stable molten globule states of the cytosolic proteins, gamma-crystallin and myoglobin, have been prepared. Within the lens, gamma-crystallin naturally interacts with alpha-crystallin and myoglobin and alpha-crystallin are present together in muscle tissue. The molten globule states of gamma-crystallin and myoglobin were prepared by reacting gamma-crystallin with glucose 6-phosphate and by removing the haem group of myoglobin. Following spectroscopic characterisation of these modified proteins, their interaction with alpha-crystallin was examined by a variety of spectroscopic and protein chemical techniques. In both cases, there was no interaction with alpha-crystallin that led to complexation. It is concluded that alpha-crystallin does not recognise stable molten globule states of cytosolic 'substrate' proteins and only interacts with molten globule states of proteins that are on the irreversible pathway towards an aggregated and precipitated form. 相似文献
132.
The ability of Methylosinus trichosporium OB3b, expressing soluble methane monooxygenase, to oxidize a range of ortho-substituted biphenyls was examined to better understand how substituents affect both the rate and products of oxidation in comparison to biphenyl. Inhibition of oxidation was observed over the tested substrate range for both biphenyl and ortho-halogenated biphenyls (2-chloro-, 2-bromo-, and 2-iodobiphenyl). No inhibition was observed during the oxidation of 2-hydroxybiphenyl and 2-methylbiphenyl. Analysis of the products of oxidation showed that, depending on the substituent, ring hydroxylation, substituent oxidation, and elimination pathways could occur. The type and abundance of products formed along with the relatively high kinetic isotope effect observed for deuterated vs. nondeuterated biphenyl (k(h)/k(d) = 3.4+/-0.02) are consistent with mechanisms that include both hydrogen abstraction and NIH-shift pathways. Knowledge of these substituent-dependent reaction rates and mechanisms enhances our understanding of the methanotrophic aryl transformation potential and allows for better prediction of the formation of oxidized intermediates by methanotrophic bacteria. 相似文献
133.
Gallagher PJ Jin Y Killough G Blue EK Lindner V 《American journal of physiology. Cell physiology》2000,279(4):C1078-C1087
Histochemical analysis ofballoon-injured rat carotid arteries revealed a coordinated expressionof nonmuscle myosin heavy chain-A and -B (NM-A and NM-B) in response toinjury. Expression of these nonmuscle myosin forms shifts from themedia to the adventitia and intima. In contrast, expression of smoothmuscle myosin heavy chain-1 (SM-1) within the media is not altered,whereas smooth muscle myosin heavy chain-2 (SM-2) expression declines.Western blotting shows a statistically significant increase inexpression of NM-A that occurs within 6 h in response to carotidinjury, suggesting this myosin form may be an appropriate experimental marker for proliferating, migrating cells in injured vessels. Nooverall change in the relative expression level of NM-B was detected,suggesting that compensatory declines in media expression are balancedby increases in the intima and adventitia. Expression of SM-1 did notchange in response to injury, whereas the expression of SM-2significantly declined between 24 h and 7 days. Expression ofmyosin light chain kinase is also negatively regulated, and the declinein its expression parallels downregulation of SM-2. 相似文献
134.
135.
Atomic force microscopy detects changes in the interaction forces between GroEL and substrate proteins. 总被引:2,自引:0,他引:2
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A Vinckier P Gervasoni F Zaugg U Ziegler P Lindner P Groscurth A Plückthun G Semenza 《Biophysical journal》1998,74(6):3256-3263
The structure of the Escherichia coli chaperonin GroEL has been investigated by tapping-mode atomic force microscopy (AFM) under liquid. High-resolution images can be obtained, which show the up-right position of GroEL adsorbed on mica with the substrate-binding site on top. Because of this orientation, the interaction between GroEL and two substrate proteins, citrate synthase from Saccharomyces cerevisiae with a destabilizing Gly-->Ala mutation and RTEM beta-lactamase from Escherichia coli with two Cys-->Ala mutations, could be studied by force spectroscopy under different conditions. The results show that the interaction force decreases in the presence of ATP (but not of ATPgammaS) and that the force is smaller for native-like proteins than for the fully denatured ones. It also demonstrates that the interaction energy with GroEL increases with increasing molecular weight. By measuring the interaction force changes between the chaperonin and the two different substrate proteins, we could specifically detect GroEL conformational changes upon nucleotide binding. 相似文献
136.
A. Wiese M. Münstermann T. Gutsmann B. Lindner K. Kawahara U. Zähringer U. Seydel 《The Journal of membrane biology》1998,162(2):127-138
We have studied the interaction of the polycationic peptide antibiotic polymyxin B (PMB) with asymmetric planar bilayer membranes
via electrical measurements. The bilayers were of different compositions, including those of the lipid matrices of the outer
membranes of various species of Gram-negative bacteria. One leaflet, representing the bacterial inner leaflet, consisted of
a phospholipid mixture (PL; phosphatidylethanolamine, -glycerol, and diphosphatidylglycerol in a molar ratio of 81:17:2).
The other (outer) leaflet consisted either of lipopolysaccharide (LPS) from deep rough mutants of PMB-sensitive (Escherichia coli F515) or -resistant strains (Proteus mirabilis R45), glycosphingolipid (GSL-1) from Sphingomonas paucimobilis IAM 12576, or phospholipids (phosphatidylglycerol, diphytanoylphosphatidylcholine). In all membrane systems, the addition
of PMB to the outer leaflet led to the induction of current fluctuations due to transient membrane lesions. The minimal PMB
concentration required for the induction of the lesions and their size correlated with the charge of the lipid molecules.
In the membrane system resembling the lipid matrix of a PMB-sensitive strain (F515 LPS/PL), the diameters of the lesions were
large enough (d= 2.4 nm ± 8%) to allow PMB molecules to permeate (self-promoted transport), but in all other systems they were too small.
A comparison of these phenomena with membrane effects induced by detergents (dodecyltriphenylphosphonium bromide, dodecyltrimethylammonium
bromide, sodiumdodecylsulfate) revealed a detergent-like mechanism of the PMB-membrane interaction.
Received: 16 September 1997/Revised: 25 November 1997 相似文献
137.
138.
Adriana Turqueti-Neves Manuel Otte Christian Schwartz Michaela Erika Renate Schmitt Cornelia Lindner Oliver Pabst Philipp Yu David Voehringer 《PLoS biology》2015,13(11)
IgE-mediated activation of mast cells and basophils contributes to protective immunity against helminths but also causes allergic responses. The development and persistence of IgE responses are poorly understood, which is in part due to the low number of IgE-producing cells. Here, we used next generation sequencing to uncover a striking overlap between the IgE and IgG1 repertoires in helminth-infected or OVA/alum-immunized wild-type BALB/c mice. The memory IgE response after secondary infection induced a strong increase of IgE+ plasma cells in spleen and lymph nodes. In contrast, germinal center B cells did not increase during secondary infection. Unexpectedly, the memory IgE response was lost in mice where the extracellular part of IgG1 had been replaced with IgE sequences. Adoptive transfer studies revealed that IgG1+ B cells were required and sufficient to constitute the memory IgE response in recipient mice. T cell-derived IL-4/IL-13 was required for the memory IgE response but not for expansion of B cells from memory mice. Together, our results reveal a close relationship between the IgE and IgG1 repertoires in vivo and demonstrate that the memory IgE response is mainly conserved at the level of memory IgG1+ B cells. Therefore, targeting the generation and survival of allergen-specific IgG1+ B cells could lead to development of new therapeutic strategies to treat chronic allergic disorders. 相似文献
139.
Steffen N. Lindner Sandra Knebel Srinivas R. Pallerla Siegfried M. Schoberth Volker F. Wendisch 《Applied microbiology and biotechnology》2010,87(2):703-713
The Corynebacterium glutamicum gene cg2091 is encoding a polyphosphate (PolyP)/ATP-dependent glucokinase (PPGK). Previous work demonstrated the association
of PPGK to PolyP granules. The deduced amino acid sequence of PPGK shows 45% sequence identity to PolyP/ATP glucomannokinase
of Arthrobacter sp. strain KM and 50% sequence identity to PolyP glucokinase of Mycobacterium tuberculosis H37Rv. PPGK from C. glutamicum was purified from recombinant Escherichia coli. PolyP was highly preferred over ATP and other NTPs as substrate and with respect to the tested PolyPs differing in chain
length; the protein was most active with PolyP75. Gel filtration analysis revealed that PolyP supported the formation of homodimers of PPGK and that PPGK was active as a
homodimer. A ppgK deletion mutant (ΔppgK) showed slowed growth in minimal medium with maltose as sole carbon source. Moreover, in minimal medium containing 2 to 4%
(w/v) glucose as carbon source, ΔppgK grew to lower final biomass concentrations than the wild type. Under phosphate starvation conditions, growth of ΔppgK was reduced, and growth of a ppgK overexpressing strain was increased as compared to wild type and empty vector control, respectively. Thus, under conditions
of glucose excess, the presence of PPGK entailed a growth advantage. 相似文献
140.