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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chromatium vinosum contains a polypeptide that is functionally and structurally similar to the Escherichia coli chaperonin 10. The protein has been purified to homogeneity by sucrose density gradient centrifugation followed by gel filtration using a Bio-Gel A-1.5 m column. The molecular mass of chaperonin 10, as determined by gel filtration or nondenaturing polyacrylamide gel electrophoresis, is 95 kDa. The oligomer is composed of seven or eight subunits. Comparisons of the overall amino acid composition and N-terminal sequences among chaperonin 10 species from C. vinosum and E. coli reflect a high degree of similarity. A physical association between chaperonins 60 and 10 from C. vinosum, in vitro, is supported by three experimental approaches. First, the proteins form a stable binary complex in sucrose density gradients, gel filtration chromatography, and nondenaturing polyacrylamide gel electrophoresis, solely in the presence of ATP and Mg2+. Second, chaperonin 10 from C. vinosum binds, selectively, to a chaperonin 60-coupled Affi-Gel 10 matrix column. Third, a slight molar excess of chaperonin 10 is able to abolish, almost completely, the ATPase in chaperonin 60. The rate for ATPase activity of chaperonin 60 from C. vinosum is enhanced when supplemented with monovalent cations.
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PMID:Purification and characterization of chaperonin 10 from Chromatium vinosum. 134 70

The promoter region of the agarase gene (dagA) of Streptomyces coelicolor A3(2) is complex; it consists of four distinct promoters with different -10 and -35 regions. We report the isolation of a form of RNA polymerase that mediates transcription in vitro from the dagAp4 promoter. The core components of this RNA polymerase are associated with a polypeptide of c. 66 kDa; holoenzyme reconstitution experiments show that the 66 kDa polypeptide functions as a sigma factor that directs transcription from the dagAp4 and Bacillus subtilis veg promoters in vitro. Alignment of the DNA sequences of these two promoters shows that they have bases in common in the -10 and -35 regions and that these sequences are similar to those observed for the major RNA polymerases of other bacteria. N-terminal amino acid sequence analysis of the 66 kDa polypeptide revealed it to be the product of the hrdB gene. Previous experiments showed that the predicted amino acid sequence of the hrdB gene product is very similar to the major sigma factors of other bacteria and suggested that disruption of the hrdB gene is lethal. These observations together lead to the conclusion that we have isolated the major RNA polymerase of Streptomyces coelicolor A3(2). We have developed an improved protocol for the renaturation of sigma factors that have been isolated by preparative sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS-PAGE). This method involves renaturing the polypeptide in the presence of the bacterial chaperonin GroEL. We expect this protocol to find general application for renaturation of other polypeptides that have been subjected to SDS-PAGE.
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PMID:Isolation and characterization of the major vegetative RNA polymerase of Streptomyces coelicolor A3(2); renaturation of a sigma subunit using GroEL. 135 Mar 15

We have examined the expression in Escherichia coli of genes encoding a plant chloroplast molecular chaperone, chaperonin-60. Purified plant chaperonin-60 is distinct in that it contains two polypeptides, p60cpn-60 alpha and p60cpn-60 beta, which have divergent amino acid sequences (Hemmingsen, S. M., and Ellis, R. J. (1986) Plant Physiol. 80, 269-276; Martel, R., Cloney, L. P., Pelcher, L. E., and Hemmingsen, S. M. (1990) Gene (Amst.) 94, 181-187). The precise polypeptide composition(s) of the active tetradecameric specie(s) (cpn60(14)) has not been determined. Genes encoding the mature forms of the Brassica napus chaperonin polypeptides have been expressed separately and in combination in E. coli to produce three novel strains: alpha, beta, and alpha beta. The plant cpn60 polypeptides accumulated in soluble forms and to similar high levels in each. There was no conclusive evidence that p60cpn-60 alpha assembled into cpn60(14) species in alpha cells. In beta and alpha beta cells, the plant gene products assembled efficiently into cpn60(14) species. Thus, the assembly of p60cpn-60 alpha required the presence of p60cpn-60 beta, whereas the assembly of p60cpn-60 beta could occur in the absence of p60cpn-60 alpha. Significant proportions of the endogenous groEL polypeptides were not assembled into tetradecameric groEL14 in beta and alpha beta cells. Analysis of the tetradecameric species that did form indicated the presence of novel hybrid cpn6014 species that contained both plant and bacterial cpn60 polypeptides.
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PMID:Expression of plant chaperonin-60 genes in Escherichia coli. 135 82

The mechanism of GroEL (chaperonin)-mediated protein folding is only partially understood. We have analysed structural and functional properties of the interaction between GroEL and the co-chaperonin GroES. The stoichiometry of the GroEL 14mer and the GroES 7mer in the functional holo-chaperonin is 1:1. GroES protects half of the GroEL subunits from proteolytic truncation of the approximately 50 C-terminal residues. Removal of this region results in an inhibition of the GroEL ATPase, mimicking the effect of GroES on full-length GroEL. Image analysis of electron micrographs revealed that GroES binding triggers conspicuous conformational changes both in the GroES adjacent end and at the opposite end of the GroEL cylinder. This apparently prohibits the association of a second GroES oligomer. Addition of denatured polypeptide leads to the appearance of irregularly shaped, stain-excluding masses within the GroEL double-ring, which are larger with bound alcohol oxidase (75 kDa) than with rhodanese (35 kDa). We conclude that the functional complex of GroEL and GroES is characterized by asymmetrical binding of GroES to one end of the GroEL cylinder and suggest that binding of the substrate protein occurs within the central cavity of GroEL.
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PMID:Chaperonin-mediated protein folding: GroES binds to one end of the GroEL cylinder, which accommodates the protein substrate within its central cavity. 136 Nov 69

T-complex polypeptide 1 (TCP-1) was analyzed as a potential chaperonin (GroEL/Hsp60) equivalent of the eukaryotic cytosol. We found TCP-1 to be part of a hetero-oligomeric 970 kDa complex containing several structurally related subunits of 52-65 kDa. These members of a new protein family are assembled into a TCP-1 ring complex (TRiC) which resembles the GroEL double ring. The main function of TRiC appears to be in chaperoning monomeric protein folding: TRiC binds unfolded polypeptides, thereby preventing their aggregation, and mediates the ATP-dependent renaturation of unfolded firefly luciferase and tubulin. At least in vitro, TRiC appears to function independently of a small co-chaperonin protein such as GroES. Folding of luciferase is mediated by TRiC but not by GroEL/ES. This suggests that the range of substrate proteins interacting productively with TRiC may differ from that of GroEL. We propose that TRiC mediates the folding of cytosolic proteins by a mechanism distinct from that of the chaperonins in specific aspects.
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PMID:Function in protein folding of TRiC, a cytosolic ring complex containing TCP-1 and structurally related subunits. 136 Nov 70

Products of a number of mutant p53 genes bind with high affinity to members of the hsp70 family of chaperonin proteins, whereas wild type p53 lacks this type of association. Examination of the sequences of p53 genes from five different species enabled us to predict domains on p53 which may be involved in the association with hsp70 family members. A synthetic polypeptide (Pro-17-Gly) corresponding to the candidate hsp70 binding domain bound to in vitro translated hsp70 as determined by affinity chromatography and nondenaturing gel mobility shift assays. In addition, the Pro-17-Gly peptide competitively inhibited association between hsp70 and p53, an activity which was determined by immunoprecipitation with anti-p53 monoclonal antibody PAb240. The data indicate that p53 contains a hsp70 binding domain, which is located in a highly conserved region at the amino terminus of the protein, and may participate in the cellular function of wild-type p53 or in the transforming capacity of p53 mutants.
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PMID:hsp70 binds specifically to a peptide derived from the highly conserved domain (I) region of p53. 156 24

The murine t-complex encodes t-complex polypeptide-1 (TCP1), which is constitutively expressed in almost all cells, and upregulated during spermatogenesis. Mammalian sequences have greater than 96% identity with each other, and greater than 60% identity with Drosophila melanogaster and yeast orthologues. TCP1 is essential in yeast, and is postulated to be the cytosolic mammalian equivalent of groEL. We report here that, in the native state, murine and human TCP1 is distributed throughout the cytosol as an 800K-950K hetero-oligomeric particle in association with four to six unidentified proteins and two Hsp70 heat-shock proteins. Negative-stain electron microscopy indicates that the structure is two stacked rings, 12-16 nm in diameter. Therefore, despite similarities with the chaperonin 60 proteins, these data indicate that TCP1 is biochemically and structurally unique. We suggest that TCP1 may represent one of a family of molecules in the eukaryotic cytosol involved in protein folding and regulated in part by their heteromeric associations.
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PMID:T-complex polypeptide-1 is a subunit of a heteromeric particle in the eukaryotic cytosol. 135 57

Chaperones facilitate folding and assembly of nascent polypeptides in vivo and prevent aggregation in refolding assays in vitro. A given chaperone acts on a number of different proteins. Thus, chaperones must recognize features present in incompletely folded polypeptide chains and not strictly dependent on primary structural information. We have used transferred nuclear Overhauser effects to demonstrate that the Escherichia coli chaperonin GroEL binds to a peptide corresponding to the N-terminal alpha-helix in rhodanese, a mitochondrial protein whose in vitro refolding is facilitated by addition of GroEL, GroES, and ATP. Furthermore, the peptide, which is unstructured when free in aqueous solution, adopts an alpha-helical conformation upon binding to GroEL. Modification of the peptide to reduce its intrinsic propensity to take up alpha-helical structure lowered its affinity for GroEL, but, nonetheless, it could be bound and took up a helical conformation when bound. We propose that GroEL interacts with sequences in an incompletely folded chain that have the potential to adopt an amphipathic alpha-helix and that the chaperonin binding site promotes formation of a helix.
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PMID:The chaperonin GroEL binds a polypeptide in an alpha-helical conformation. 167 68

The nucleotide sequence of the luxA and luxB genes encoding the alpha beta heterodimeric luciferase from thermotolerant Vibrio harveyi CTP5 was determined. The DNA sequence of the CTP5 luxA and luxB genes is identical to the DNA sequence of the luxA and luxB genes from mesophilic V. harveyi MAV (B 392), with minor exceptions. The sequence differences result in 5 amino acid substitutions in the alpha subunit polypeptide and 7 amino acid substitutions in the beta subunit polypeptide. Escherichia coli cells grown on solid medium and expressing CTP5 or MAV luxAB genes emit similar amounts of light at 37 degrees C, while at 42 degrees C cells containing CTP5 luxAB genes show more than tenfold increased bioluminescence compared to cells with MAV luxAB genes. When grown in liquid medium E. coli cells with CTP5 or MAV luxAB genes emit equivalent amounts of light at 37 degrees C; however, in liquid medium at 42 degrees C cells containing CTP5 luxAB genes show only three times higher bioluminescence than cells with MAV luxAB genes. Expression of T7 promoter-linked hybrid luxAB transcriptional units luxACTP5-luxBMAV and luxAMAV-luxBCTP5 in E. coli reveals that (i) the MAV luxB gene product is responsible for the decreased activity of MAV luciferase at 42 degrees C; (ii) the CTP5 luxB gene encodes the information required for most of the increased activity of CTP5 luciferase relative to MAV luciferase at 42 degrees C; and (iii) E. coli cells containing MAV luxB gene show an increase in bioluminescence when grown in liquid medium at 42 degrees C, which coincides with elevated GroEL chaperonin levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The beta subunit polypeptide of Vibrio harveyi luciferase determines light emission at 42 degrees C. 168 11

A study was performed to characterize DNA fragment No. 17 of C. psittaci strain P-1041 which encoded 42 KD beta-galactosidase fusion protein with type-specific antigenicity. Sequence determination identified a partial open reading frame that spanned about 1,200b. p. nucleotides. Screening the literatures for the nucleotide and deduced amino acid sequences revealed extensive similarity between the DNA fragment of P-1041 and two chlamydial hypB genes. This DNA showed 91.5% homology with C. psittaci GPIC hypB gene in nucleotide sequence and 96.4% homology in deduced amino acid sequence. The hypB gene of C. trachomatis serovar A and the P-1041 DNA fragment showed 81.2% and 91.3% homology in nucleotide and amino acid sequences, respectively. Dot enzyme-linked immunosorbent assay, for the products of deleted DNA fragments defined the coding region for type-specific antigenic polypeptide. In addition, the P-1041 DNA fragment carried a sequence highly homologous (greater than 49%) with other bacterial and plant genes called chaperonin which responds to various stress in cells. From these results, the P-1041 DNA fragment was found to be a part of hypB gene and to encode the region critical for type-specific antigenicity.
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PMID:Characterization of DNA fragment from Chlamydia psittaci avian strain which shows high homology with hypB gene of Chlamydia. 182 39


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