Primary structure of a human mitochondrial protein homologous to the bacterial and plant chaperonins and to the 65-kilodalton mycobacterial antigen.

Abstract

The complete cDNA for a human mitochondrial protein designated P1, which was previously identified as a microtubule-related protein, has been cloned and sequenced. The deduced amino acid sequence of P1 shows strong homology (40 to 50% identical residues and an additional 20% conservative replacements) to the 65-kilodalton major antigen of mycobacteria, to the GroEL protein of Escherichia coli, and to the ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) subunit binding protein of plant chloroplasts. Similar to the case with the latter two proteins, which have been shown to act as chaperonins in the posttranslational assembly of oligomeric protein structures, it is suggested that P1 may play a similar role in mammalian cells. The observed high degree of homology between human P1 and mycobacterial antigen also suggests the possible involvement of this protein in certain autoimmune diseases.Our earlier studies with mutants of Chinese hamster ovary (CHO) cells selected for resistance to the microtubule (MT) inhibitor podophyllotoxin showed that a large number of these mutants involved specific electrophoretic alteration in a major protein designated P1 (Mr, 63 kilodaltons [kDa]) (6, 7). The genetic lesion in these mutants appears to be related to the cellular action of the drug, since podophyllotoxinresistant mutants exhibit highly specific cross-resistance and collateral sensitivity to other MT inhibitors, such as colchicine, nocodazole, and taxol, and show reduced binding of the drug in cell extracts (6, 7). Immunofluorescence studies show that in interphase cells of vertebrate and invertebrate species, P1 antibody stains mitochondria, which show specific association with MTs (5, 7). Subfractionation of rat mitochondria has localized P1 to the matrix compartment (4). To help understand the cellular function of P1, cloning and sequencing of P1 cDNA from human cells was undertaken. The P1 sequence reported here shows extensive sequence and structural homology to a family of bacterial and plant proteins, termed chaperonins (8), which are involved in facilitating the posttranslational assembly of oligomeric protein complexes (1,3,8), as well as to the 65-kDa major antigenic protein of mycobacterial species (15,(18)(19)(20). The observed high degree of sequence and structural similarity between these proteins strongly indicates that P1 is the human homolog of this evolutionarily highly conserved group of proteins.Isolation of Pl-specific clones from kgtll libraries. We have previously demonstrated that our antibodies to P1 crossreact only with the P1 protein in one-and two-dimensional immunoblots of proteins from CHO and human cells (5, 7).

Mycobacterium tuberculosis employs Cpn60.2 as an adhesin that binds CD43 on the macrophage surface

“…Mammalian Hsp60 proteins commonly share 40-50% amino acid sequence homology with Cpn60.2 (Jindal et al, 1989;Tasci et al, 1998). It has been shown that mammalian and bacterial homologues of Hsp60/65 bind to the MF at different sites (Habich et al, 2003) and the findings from our competitive inhibition assay (Fig.…”

Effect of Microbial Heat Shock Proteins on Airway Inflammation and Hyperresponsiveness

“…Furthermore, eosinophilia in the lung tissue and airways was prevented after treatment with M. leprae hsp, but not with the other hsp. These findings imply that despite their enormous conservation in amino acid sequences (36), microbial hsp differ in their immunological properties.…”

Analysis of the polyadenylation consensus sequence context in the genes of nuclear encoded mitochondrial proteins

“…(B cyt45011); rat ornithine carbamoyltransferase [36], (R oct); human pyruvate dehydrogenase EI~ subunit [37], (H PyrDhE1); bovine mitochondrial adenylate kinase 2 [38], (B AK2A, B AK2B); bovine mitochondrial carrier protein [39], (B mtPcP); rat mitochondrial 3-oxoacyl-CoA thiolase [40], (R 3oxCoth); human liver glutamate dehydrogenase [41], (H GDH); rat heart and liver subunit Via of cytochrome oxidase [42], (R hcoxVIa. R IcoxVla); mouse mitochondrial uncoupling protein [43], (M Ucp, M Ucp/min); mouse ornithine transcarbamylase [44], (Motc); mouse mitochondrial malate dehydrogenase [45], (M mMDH); human cytochrome oxidase subunit Vie [46], (H coxVIc); human aspartate amino transferase [47], (H mAspAT); rat liver mitochondrial NADH dehydrogenase 24-kDa subunit [67], (H cox-VIII); murine NAD-dependent methylenetetrahydrofolate dehydrogenase-melthylenyltetrahydrofolate cyclohydrolase [68], (M MTHFdeh); bovine GTP:AMP phosphotransferase [69], (B AK3); bovine NADH-ubiquinone reductase [70], (B ubiqred); human methylmalonyl-CoA mutase [71], (H Metmlmt); human mitochondrial protein homologous to the bacterial and plant chaperonms [72], (H PI); porcine testis cytochrome P-450 (SCC) [73], (P cytp450); human cytochrome oxidase subunit Vlb [74], (H coxVIb); human creatine kinase [7'5]. (H CK); rat fumarase [76], (R mtFumra); human branched chain ~-keto acid dehydrogenase complex subunit E1 ~ [77], (H E1 BCKD); rat brain and liver cytochrome oxidase subunit IV [78], (R coxlV); bovine uncoupling protein [79], (B Ucp); rat cytochrome c oxidase subunh Via (Vb) [80], (R coxVb); human cytochrome c oxidase subunit Via [81], (H coxVia); human NAD-dependent methylene tetrahydrofolate dehydrogenase-cyc!ohydrolase [82], (H MTHFdeh); rat short chain acyl-CoA dehydrogenase and isovaleryl-CoA dehydrogenase [83], (R SCCode, R IVD); mouse cytochrome oxidase subunit Ya [84], (M coxVa); human cytochrome bcl complex core protein 2 [85]; human cytOchrome c oxidase subunit VIIa …”