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981.
Petra Behnen Alexander Scholten Nina Rätscho Karl-Wilhelm Koch 《Journal of biological inorganic chemistry》2009,14(1):89-99
Guanylate cyclase activating proteins (GCAPs) serve as neuronal Ca2+-sensor proteins in vertebrate rod and cone photoreceptor cells. Zebrafish express in their retina a variety of six different
GCAPs, of which four are specific for cone cells. One isoform, zGCAP4, is mainly expressed in double cones and long single
cones. We cloned the zGCAP4 gene, purified non-myristoylated and myristoylated forms of the protein after heterologous expression
in Escherichia coli and studied its properties: zGCAP4 was a strong activator of membrane-bound guanylate cyclases from bovine and zebrafish
retina, showing half-maximal activation at 520–570 nM free Ca2+ concentration. Furthermore, the Ca2+-sensitive activation properties of non-myristoylated and myristoylated zGCAP4 were similar, indicating no influence of the
myristoyl moiety on Ca2+-sensor function. Myristoylated zGCAP4 showed low affinity for membranes and did not exhibit a Ca2+–myristoyl switch, a feature typical of some but not all neuronal Ca2+-sensor proteins. However, tryptophan fluorescence studies and Ca2+-dependent differences in protease accessibility revealed Ca2+-induced conformational changes in myristoylated and non-myristoylated zGCAP4, indicating the operation as a Ca2+ sensor. Thus, expression and biochemical properties of zGCAP4 are in agreement with its function as an efficient Ca2+-sensitive regulator of guanylate cyclase activity in cone vision. 相似文献
982.
Herve Y. Sroussi Gerwald A. Köhler Nina Agabian Dana Villines & Joel M. Palefsky 《FEMS immunology and medical microbiology》2009,55(1):55-61
S100A8 and S100A9 and their heterocomplex calprotectin (S100A8/A9) are abundant cytosolic constituents in human neutrophils previously shown to possess antifungal activity. This study was designed to investigate mechanisms involved in the modulation of the antifungal properties of S100A8/A9. S100A8, S100A9 and site-directed mutants of both proteins were tested for their antifungal effect against Candida albicans in microplate dilution assays. Whereas S100A8 alone did not inhibit fungal growth, S100A9 by itself had a moderate antifungal effect. Combining both proteins had the strongest effect. Supporting a potential role for oxidation in S100A8/A9, substitution of methionine 63 or 83 of S100A9 resulted in the loss of antifungal activity. Additionally, the substitution to alanine of cysteine 42 of S100A8 also caused a loss of S100A8's ability to enhance S100A9's antifungal effect. Overall, our data indicate that both S100A8 and S100A9 are required for their fully active antifungal effect and that oxidation regulates S100A8/A9 antifungal activity through mechanisms that remain to be elucidated and evaluated. Finally, together with our previous work describing the oxidation-sensitive anti-inflammatory effects of S100A8/A9, we propose that S100A8/A9 exerts an anti-inflammatory activity in healthy state and that conditions associated with oxidative stress activate the antifungal activity of S100A8/A9. 相似文献
983.
Nina Gehde Corinna Hinrichs Irine Montilla Stefan Charpian Klaus Lingelbach Jude M. Przyborski 《Molecular microbiology》2009,71(3):613-628
Plasmodium falciparum traffics a large number of proteins to its host cell, the mature human erythrocyte. How exactly these proteins gain access to the red blood cell is poorly understood. Here we have investigated the effect of protein folding on the transport of model substrate proteins to the host cell. We find that proteins must pass into the erythrocyte cytoplasm in an unfolded state. Our data strongly support the presence of a protein-conducing channel in the parasitophorous vacoular membrane, and additionally imply an important role for molecular chaperones in keeping parasite proteins in a 'translocation competent' state prior to membrane passage. 相似文献
984.
985.
Nina A. Kocharova Olga G. Ovchinnikova Andrei V. Perepelov Alexander S. Shashkov Yuriy A. Knirel 《Carbohydrate research》2009,344(15):2060-3577
O-Polysaccharides were released by mild acid degradation of lipopolysaccharides of Providencia alcalifaciens O35 and Proteus vulgaris O76 and were studied by 1D and 2D 1H and 13C NMR spectroscopies, including HMBC and NOESY (ROESY) experiments. Both polysaccharides were found to contain N-(1-carboxyethyl)alanine (alanopine) that is N-linked to 4-amino-4,6-dideoxyglucose. Analysis of published data [Vinogradov, E.; Perry, M. B. Eur. J. Biochem.2000, 267, 2439-2446] shows that alanopine is present also on the same sugar in the lipopolysaccharide core of Proteus mirabilis O6 and O57. 相似文献
986.
The Plasmid-Encoded Regulator Activates Factors Conferring Lysozyme Resistance on Enteropathogenic Escherichia coli Strains
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We demonstrate that enhanced lysozyme resistance of enteropathogenic Escherichia coli requires the plasmid-encoded regulator, Per, and is mediated by factors outside the locus for enterocyte effacement. EspC, a Per-activated serine protease autotransporter protein, conferred enhanced resistance on nonpathogenic E. coli, and a second Per-regulated, espC-independent lysozyme resistance mechanism was identified. 相似文献
987.
988.
989.
Kenneth R. Wilund Mira Rosenblat Nina Volkova Jeffrey A. Woods 《Biochemical and biophysical research communications》2009,390(1):148-140
Objective
The parasympathetic nervous system regulates inflammation in peripheral tissues through a pathway termed the “cholinergic anti-inflammatory reflex” (CAIR). Mice deficient in the alpha 7 nicotinic acetylcholine receptor (α7−/−) have an impaired CAIR due to decreased signaling through this pathway. The purpose of this study was to determine if the increased inflammation in α7−/− mice is associated with enhanced serum and macrophage atherogenicity.Methods
We measured serum markers of inflammation and oxidative stress, and macrophage atherogenicity in mouse peritoneal macrophages harvested from α7−/− mice on the background of C57BL/6 mice, as well as on the background of the atherosclerotic Apolipoprotein E-deficient (ApoE−/−) mice.Results
α7-Deficiency had no significant effects on serum cholesterol, or on markers of serum oxidative stress (TBARS and paraoxonase1 activities). However, α7-deficiency significantly increased serum CRP and IL-6 (p < 0.05) levels in atherosclerotic mice, confirming an anti-inflammatory role for the α7 receptor. Macrophage cholesterol mass was increased by 25% in both normal and atherosclerotic mice in the absence of the α7 receptor (p < 0.05). This was accompanied by conditional increases in oxidized LDL uptake and in macrophage total peroxide levels. Furthermore, α7-deficiency reduced macrophage paraoxonase2 mRNA and activity by 50-100% in normal and atherosclerotic mice (p < 0.05 for each), indicating a reduction in macrophage anti-oxidant capacity in the α7−/− mice.Conclusion
The above results suggest an anti-atherogenic role for the macrophage α7nAchr, through a mechanism that involves attenuated macrophage oxidative stress and decreased uptake of oxidized LDL. 相似文献990.
Matthias Schultze Björn Forberich Sascha Rexroth Nina Gwendolyn Dyczmons Matthias Roegner Jens Appel 《BBA》2009,1787(12):1479-1485
The cytochrome b6f complex is an integral part of the photosynthetic and respiratory electron transfer chain of oxygenic photosynthetic bacteria. The core of this complex is composed of four subunits, cytochrome b, cytochrome f, subunit IV and the Rieske protein (PetC). In this study deletion mutants of all three petC genes of Synechocystis sp. PCC 6803 were constructed to investigate their localization, involvement in electron transfer, respiration and photohydrogen evolution. Immunoblots revealed that PetC1, PetC2, and all other core subunits were exclusively localized in the thylakoids, while the third Rieske protein (PetC3) was the only subunit found in the cytoplasmic membrane. Deletion of petC3 and both of the quinol oxidases failed to elicit a change in respiration rate, when compared to the respective oxidase mutant. This supports a different function of PetC3 other than respiratory electron transfer. We conclude that the cytoplasmic membrane of Synechocystis lacks both a cytochrome c oxidase and the cytochrome b6f complex and present a model for the major electron transfer pathways in the two membranes of Synechocystis. In this model there is no proton pumping electron transfer complex in the cytoplasmic membrane.Cyclic electron transfer was impaired in all petC1 mutants. Nonetheless, hydrogenase activity and photohydrogen evolution of all mutants were similar to wild type cells. A reduced linear electron transfer and an increased quinol oxidase activity seem to counteract an increased hydrogen evolution in this case. This adds further support to the close interplay between the cytochrome bd oxidase and the bidirectional hydrogenase. 相似文献