Species-specific and mutant MWFE proteins. Their effect on the assembly of a functional mammalian mitochondrial complex I.
The MWFE protein (70 amino acids) is highly conserved in evolution, but the human protein (80% identical to hamster) does not complement a null mutation in Chinese hamster cells. We have identified a small protein segment where significant differences exist between rodents and primates, illustrating very specifically the need for compatibility of the nuclear and mitochondrial genomes in the assembly of complex I. The segment between amino acids 39 and 46 appears to be critical for species-specific compatibility. Amino acid substitutions in this region were tested that caused a reduction of activity of the hamster protein or converted the inactive human protein into a partially active one. Such mutations could be useful in making mice with partial complex I activity as models for mitochondrial diseases. Their potential as dominant negative mutants was explored. More deleterious mutations in the NDUFA1 gene were also characterized. A conservative substitution, R50K, or a short C-terminal deletion makes the protein completely inactive. In the absence of MWFE, no high molecular weight complex was detectable by Blue Native-gel electrophoresis. The MWFE protein itself is unstable in the absence of assembled mitochondrially encoded integral membrane proteins of complex I.
Yadava
Nagendra
N
Division of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, California 92093-0322, USA.
Potluri
Prasanth
P
Smith
Erin N
EN
Bisevac
Amina
A
Scheffler
Immo E
IE
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D016466:CHO Cells; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D042967:Electron Transport Complex I; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D005799:Genes, Dominant; D005816:Genetic Complementation Test; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000737:chemistry*; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009245:NADH Dehydrogenase; D010101:Oxygen Consumption; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013045:Species Specificity; D013997:Time Factors
D018076:DNA, Complementary; D008565:Membrane Proteins; C492251:Ndufa1 protein, mammalian; D010455:Peptides; D012333:RNA, Messenger; D009245:NADH Dehydrogenase; D042967:Electron Transport Complex I; C118736:NDUFA1 protein, human; C492250:Ndufa1 protein, mouse