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111.
The sperm outer dense fiber protein is the 10th member of the superfamily of mammalian small stress proteins 总被引:2,自引:0,他引:2 下载免费PDF全文
Nine proteins have been assigned to date to the superfamily of mammalian small heat shock proteins (sHsps): Hsp27 (HspB1, Hsp25), myotonic dystrophy protein kinase-binding protein (MKBP) (HspB2), HspB3, alphaA-crystallin (HspB4), alphaB-crystallin (HspB5), Hsp20 (p20, HspB6), cardiovascular heat shock protein (cvHsp [HspB7]), Hsp22 (HspB8), and HspB9. The most pronounced structural feature of sHsps is the alpha-crystallin domain, a conserved stretch of approximately 80 amino acid residues in the C-terminal half of the molecule. Using the alpha-crystallin domain of human Hsp27 as query in a BLAST search, we found sequence similarity with another mammalian protein, the sperm outer dense fiber protein (ODFP). ODFP occurs exclusively in the axoneme of sperm cells. Multiple alignment of human ODFP with the other human sHsps reveals that the primary structure of ODFP fits into the sequence pattern that is typical for this protein superfamily: alpha-crystallin domain (conserved), N-terminal domain (less conserved), central region (variable), and C-terminal tails (variable). In a phylogenetic analysis of 167 proteins of the sHsp superfamily, using Bayesian inference, mammalian ODFPs form a clade and are nested within previously identified sHsps, some of which have been implicated in cytoskeletal functions. Both the multiple alignment and the phylogeny suggest that ODFP is the 10th member of the superfamily of mammalian sHsps, and we propose to name it HspB10 in analogy with the other sHsps. The C-terminal tail of HspB10 has a remarkable low-complexity structure consisting of 10 repeats of the motif C-X-P. A BLAST search using the C-terminal tail as query revealed similarity with sequence elements in a number of Drosophila male sperm proteins, and mammalian type I keratins and cornifin-alpha. Taken together, the following findings suggest a specialized role of HspB10 in cytoskeleton: (1) the exclusive location in sperm cell tails, (2) the phylogenetic relationship with sHsps implicated in cytoskeletal functions, and (3) the partial similarity with cytoskeletal proteins. 相似文献
112.
Retroids in archaea: phylogeny and lateral origins 总被引:3,自引:0,他引:3
113.
Ricard-Blum S Féraud O Lortat-Jacob H Rencurosi A Fukai N Dkhissi F Vittet D Imberty A Olsen BR van der Rest M 《The Journal of biological chemistry》2004,279(4):2927-2936
Endostatin (20 kDa) is a C-terminal proteolytic fragment of collagen XVIII that is localized in vascular basement membrane zones in various organs. It binds zinc, heparin/heparan sulfate, laminin, and sulfatides and inhibits angiogenesis and tumor growth. Here we determined the kinetics and affinity of the interaction of endostatin with heparin/heparan sulfate and investigated the effects of divalent cations on these interactions and on the biological activities of endostatin. The binding of human recombinant endostatin to heparin and heparan sulfate was studied by surface plasmon resonance using BIAcore technology and further characterized by docking and molecular dynamics simulations. Kinetic data, evaluated using a 1:1 interaction model, showed that heparan sulfate bound to and dissociated from endostatin faster than heparin and that endostatin bound to heparin and heparan sulfate with a moderate affinity (K(D) approximately 2 microm). Molecular modeling of the complex between endostatin and heparin oligosaccharides predicted that, compared with mutagenesis studies, two further arginine residues, Arg(47) and Arg(66), participated in the binding. The binding of endostatin to heparin and heparan sulfate required the presence of divalent cations. The addition of ZnCl(2) to endostatin enhanced its binding to heparan sulfate by approximately 40% as well as its antiproliferative effect on endothelial cells stimulated by fibroblast growth factor-2, suggesting that this activity is mediated by the binding of endostatin to heparan sulfate. In contrast, no increase in the antiangiogenic and anti-proliferative activities of endostatin promoted by vascular endothelial growth factor was observed upon the addition of zinc. 相似文献
114.
Another unusual type of citric acid cycle enzyme in Helicobacter pylori: the malate:quinone oxidoreductase 下载免费PDF全文
Kather B Stingl K van der Rest ME Altendorf K Molenaar D 《Journal of bacteriology》2000,182(11):3204-3209
The only enzyme of the citric acid cycle for which no open reading frame (ORF) was found in the Helicobacter pylori genome is the NAD-dependent malate dehydrogenase. Here, it is shown that in this organism the oxidation of malate to oxaloacetate is catalyzed by a malate:quinone oxidoreductase (MQO). This flavin adenine dinucleotide-dependent membrane-associated enzyme donates electrons to quinones of the electron transfer chain. Similar to succinate dehydrogenase, it is part of both the electron transfer chain and the citric acid cycle. MQO activity was demonstrated in isolated membranes of H. pylori. The enzyme is encoded by the ORF HP0086, which is shown by the fact that expression of the HP0086 sequence from a plasmid induces high MQO activity in mqo deletion mutants of Escherichia coli or Corynebacterium glutamicum. Furthermore, this plasmid was able to complement the phenotype of the C. glutamicum mqo deletion mutant. Interestingly, the protein predicted to be encoded by this ORF is only distantly related to known or postulated MQO sequences from other bacteria. The presence of an MQO shown here and the previously demonstrated presence of a 2-ketoglutarate:ferredoxin oxidoreductase and a succinyl-coenzyme A (CoA):acetoacetyl-CoA transferase indicate that H. pylori possesses a complete citric acid cycle, but one which deviates from the standard textbook example in three steps. 相似文献
115.
Sandra Wydau Guillaume van der Rest Caroline Aubard Pierre Plateau Sylvain Blanquet 《The Journal of biological chemistry》2009,284(21):14096-14104
Several l-aminoacyl-tRNA synthetases can transfer a
d-amino acid onto their cognate tRNA(s). This harmful reaction is
counteracted by the enzyme d-aminoacyl-tRNA deacylase. Two distinct
deacylases were already identified in bacteria (DTD1) and in archaea (DTD2),
respectively. Evidence was given that DTD1 homologs also exist in nearly all
eukaryotes, whereas DTD2 homologs occur in plants. On the other hand, several
bacteria, including most cyanobacteria, lack genes encoding a DTD1 homolog.
Here we show that Synechocystis sp. PCC6803 produces a third type of
deacylase (DTD3). Inactivation of the corresponding gene (dtd3)
renders the growth of Synechocystis sp. hypersensitive to the
presence of d-tyrosine. Based on the available genomes, DTD3-like
proteins are predicted to occur in all cyanobacteria. Moreover, one or several
dtd3-like genes can be recognized in all cellular types, arguing in
favor of the nearubiquity of an enzymatic function involved in the defense of
translational systems against invasion by d-amino acids.Although they are detected in various living organisms (reviewed in Ref.
1), d-amino acids
are thought not to be incorporated into proteins, because of the
stereospecificity of aminoacyl-tRNA synthetases and of the translational
machinery, including EF-Tu and the ribosome
(2). However, the
discrimination between l- and d-amino acids by
aminoacyl-tRNA synthetases is not equal to 100%. Significant
d-aminoacylation of their cognate tRNAs by Escherichia
coli tyrosyl-, tryptophanyl-, aspartyl-, lysyl-, and histidyl-tRNA
synthetases has been characterized in vitro
(3–9).
Recently, using a bacterium, transfer of d-tyrosine onto
tRNATyr was shown to occur in vivo
(10).With such misacylation reactions, the resulting
d-aminoacyl-tRNAs form a pool of metabolically inactive molecules,
at best. At worst, d-aminoacylated tRNAs infiltrate the protein
synthesis machinery. Although the latter harmful possibility has not yet been
firmly established, several cells were shown to possess a
d-tyrosyl-tRNA deacylase, or DTD, that should help them counteract
the accumulation of d-aminoacyl-tRNAs. This enzyme shows a broad
specificity, being able to remove various d-aminoacyl moieties from
the 3′-end of a tRNA
(4–6,
11). Such a function makes the
deacylase a member of the family of enzymes capable of editing in
trans mis-aminoacylated tRNAs. This family includes several homologs
of aminoacyl-tRNA synthetase editing domains
(12), as well as peptidyl-tRNA
hydrolase (13,
14).Two distinct deacylases have already been discovered. The first one, called
DTD1, is predicted to occur in most bacteria and eukaryotes (see
d-amino acids, including
d-tyrosine (6). In
fact, in an E. coli Δdtd strain grown in the presence
of 2.4 mm d-tyrosine, as much as 40% of the cellular
tRNATyr pool becomes esterified with d-tyrosine
(10).
Open in a separate windowHomologs of dtd/DTD1 are not found in the available archaeal
genomes except that of Methanosphaera stadtmanae. A search for
deacylase activity in Sulfolobus solfataricus and Pyrococcus
abyssi led to the detection of another enzyme (DTD2), completely
different from the DTD1 protein
(15). Importing dtd2
into E. coli functionally compensates for dtd deprivation.
As shown in 16).Several cells contain neither dtd nor dtd2 homologs
(d-tyrosyl-tRNA deacylase
(DTD3). This protein, encoded by dtd3, behaves as a metalloenzyme.
Sensitivity of the growth of Synechocystis to external
d-tyrosine is strongly exacerbated by the disruption of
dtd3. Moreover, expression of the Synechocystis DTD3 in a
Δdtd E. coli strain, from a plasmid, restores the resistance of
the bacterium to d-tyrosine. Finally, using the available genomes,
we examined the occurrence of DTD3 in the living world. The prevalence of
DTD3-like proteins is surprisingly high. It suggests that the defense of
protein synthesis against d-amino acids is universal. 相似文献
TABLE 1
Distribution of DTD1 and DTD2 homologs in various phylogenetic groupsHomologs of DTD1 and DTD2 were searched for using a genomic Blast analysis against complete genomes in the NCBI Database (www.ncbi.nlm.nih.gov). Values in the table are number of species. For instance, E. coli is counted only once in γ-proteobacteria despite the fact that several E. coli strains have been sequenced.DTD1 | DTD2 | DTD1 + DTD2 | None | |
---|---|---|---|---|
Bacteria | ||||
Acidobacteria | 2 | 0 | 0 | 0 |
Actinobacteria | 27 | 0 | 0 | 8 |
Aquificae | 1 | 0 | 0 | 0 |
Bacteroidetes/Chlorobi | 12 | 0 | 0 | 5 |
Chlamydiae | 1 | 0 | 0 | 6 |
Chloroflexi | 4 | 0 | 0 | 0 |
Cyanobacteria | 5 | 0 | 0 | 16 |
Deinococcus/Thermus | 4 | 0 | 0 | 0 |
Firmicutes | ||||
Bacillales | 19 | 0 | 0 | 0 |
Clostridia | 19 | 0 | 0 | 0 |
Lactobacillales | 23 | 0 | 0 | 0 |
Mollicutes | 0 | 0 | 0 | 15 |
Fusobacteria/Planctomycetes | 2 | 0 | 0 | 0 |
Proteobacteria | ||||
α | 6 | 0 | 0 | 55 |
β | 24 | 0 | 0 | 11 |
γ | 80 | 0 | 0 | 8 |
δ | 15 | 0 | 0 | 0 |
ε | 1 | 0 | 0 | 12 |
Spirochaetes | 0 | 0 | 0 | 7 |
Thermotogae | 5 | 0 | 0 | 0 |
Archaea | ||||
Crenarchaeota | 0 | 13 | 0 | 0 |
Euryarchaeota | 1 | 26 | 0 | 2 |
Nanoarchaeota | 0 | 0 | 0 | 1 |
Eukaryota | ||||
Dictyosteliida | 1 | 0 | 0 | 0 |
Fungi/Metazoa | ||||
Fungi | 13 | 0 | 0 | 1 |
Metazoa | 19 | 0 | 0 | 0 |
Kinetoplastida | 3 | 0 | 0 | 0 |
Viridiplantae | 4 | 4 | 4 | 0 |
116.
A heat shock following electroporation induces highly efficient transformation of Corynebacterium glutamicum with xenogeneic plasmid DNA 总被引:10,自引:0,他引:10
An improved method for the electrotransformation of wild-type Corynebacterium glutamicum (ATCC 13032) is described. The two crucial alterations to previously developed methods are: cultivation of cells used for
electrotransformation at 18 °C instead of 30 °C, and application of a heat shock immediately following electrotransformation.
Cells cultivated at sub optimal temperature have a 100-fold improved transformation efficiency (108 cfu μg−1) for syngeneic DNA (DNA isolated from the same species). A heat shock applied to these cells following electroporation improved
the transformation efficiency for xenogeneic DNA (DNA isolated from a different species). In combination, low cultivation
temperature and heat shock act synergistically and increased the transformation efficiency by four orders of magnitude to
2.5 × 106 cfu μg−1 xenogeneic DNA. The method was used to generate gene disruptions in C. glutamicum.
Received: 26 March 1999 / Received revision: 9 June 1999 / Accepted: 11 June 1999 相似文献
117.
Summary The cotyledons of Sinapis alba L. seed are the storage organs and first photosynthetic organs. The development of the cotyledon cell contents was studied using electron and light microscopy. From the heart shaped embryo (11 days from petal fall) to the mature seed, nine stages were examined.Both types of protein grains (designated aleurone grains and myrosin grains) were found to form within vacuoles, but the mode of protein accumulation differed with each type of grain.Oil bodies were apparent with the EM from 18 days onwards, but could not be seen to arise from the ER. They were granular in appearance at early stages, but later became electron transparent. 相似文献
118.
Transglutaminases catalyze the formation of Nε-(γ-glutamyl) isodipeptide crosslinks between proteins. These enzymes are thought to participate in a number of diseases, including neurological disease and cancer. A method associating liquid chromatography and multiple stage mass spectrometry has been developed for the simultaneous quantitation of [Nε-(γ-glutamyl) lysine] isodipeptide and lysine on an ion trap mass spectrometer. Highly specific detection has been achieved in MS3 mode. The method includes a derivatization step consisting of butylation of carboxylic groups and acetylation of amide groups, a liquid-liquid extraction, and a 19-min separation on a 100 × 2.1-mm Beta-basic C18 column with an acetonitrile gradient elution. 13C6-15N2 isotopes of the isodipeptide and the lysine serve as internal standards. The assay was linear in the range of 50 pmol/ml to 75 nmol/ml for the isodipeptide and the range of 10 nmol/ml to 3.5 μmol/ml for the lysine, with correlation coefficients greater than 0.99 for both ions. Intra- and inter-day coefficients of variation ranged from 3.5 to 15.9%. The method was successfully applied to human biological samples known to be crosslinked by transglutaminase such as cornified envelopes of epidermis, fibrin, and normal and Huntington disease brain. 相似文献
119.
120.