The role of the ESSS protein in the assembly of a functional and stable mammalian mitochondrial complex I (NADH-ubiquinone oxidoreductase).
The ESSS protein is a recently identified subunit of mammalian mitochondrial complex I. It is a relatively small integral membrane protein (122 amino acids) found in the beta-subcomplex. Genomic sequence database searches reveal its localization to the X-chromosome in humans and mouse. The ESSS cDNA from Chinese hamster cells was cloned and shown to complement one complementation group of our previously described mutants with a proposed X-linkage. Sequence analyses of the ESSS cDNA in these mutants revealed chain termination mutations. In two of these mutants the protein is truncated at the C-terminus of the targeting sequence; the mutants are null mutants for the ESSS subunit. There is no detectable complex I assembly and activity in the absence of the ESSS subunit as revealed by blue native polyacrylamide gel electrophoresis (BN/PAGE) analysis and polarography. Complex I activity can be restored with ESSS subunits tagged with either hemagglutinin (HA) or hexahistidine (His6) epitopes at the C-terminus. Although, the accumulation of ESSS-HA is not dependent upon the presence of mtDNA-encoded subunits (ND1-6,4 L), it is incorporated into complex I only in presence of compatible complex I subunits from the same species.
Potluri
Prasanth
P
Division of Biology, Molecular Biology Section, University of California, San Diego, California 92093-0322, USA.
Yadava
Nagendra
N
Scheffler
Immo E
IE
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D019069:Cell Respiration / Q000235:genetics; D006224:Cricetinae / Q000235:genetics; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010100:Oxygen / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D021122:Protein Subunits; D042967:Electron Transport Complex I; D010100:Oxygen