The NDUFA1 gene product (MWFE protein) is essential for activity of complex I in mammalian mitochondria

Abstract

The MWFE polypeptide of mammalian complex I (the proton-translocating NADH-quinone oxidoreductase) is 70 amino acids long, and it is predicted to be a membrane protein. The NDUFA1 gene encoding the MWFE polypeptide is located on the X chromosome. This polypeptide is 1 of approximately 28 ''accessory proteins'' identified in complex I, which is composed of 42 unlike subunits. It was considered accessory, because it is not one of the 14 polypeptides making up the core complex I; a homologous set of 14 polypeptides can make a fully functional proton-translocating NADH-quinone oxidoreductase in prokaryotes. One MWFE mutant has been identified and isolated from a collection of respiration-deficient Chinese hamster cell mutants. The CCL16-B2 mutant has suffered a deletion that would produce a truncated and abnormal MWFE protein. In these mutant cells, complex I activity is reduced severely (<10%). Complementation with hamster NDUFA1 cDNA restored the rotenone-sensitive complex I activity of these mutant cells to Ϸ100% of the parent cell activity. Thus, it is established that the MWFE polypeptide is absolutely essential for an active complex I in mammals.

Development and Characterization of a Conditional Mitochondrial Complex I Assembly System

“…V79-G7 cells expressing the inducible MWFE⅐HA were named G7-MWFE⅐HA i . Northern Analysis-Northern analysis was performed as described previously using a hamster NDUFA1 cDNA probe (3). A probe for human citrate synthase mRNA was made by reverse transcription PCR with oligonucleotide primers CS.F1 (5Ј-ATGGCTTTACTTACTGCGGC-3Ј) and CS.R1 (5Ј-CACATGGGAAGGCAGAGCTG-3Ј), which amplify a 453-bp cDNA beginning with the ATG start codon.…”

“…Differences in the biogenesis of complex I between N. crassa and humans have been noticed, for example, with regard to the exact role of the AQDQ subunit. In N. crassa, the AQDQ homologue is not essential for complex I assembly and rotenone-sensitive activity (5), whereas in human patients with a homozygous mutation in the NDUFS4 gene (AQDQ subunit) complex I assembly is severely affected (14,15).Previous studies from this laboratory have characterized a Chinese hamster mutant cell completely deficient in the MWFE subunit (encoded by the X-linked NDUFA1 gene) (3,4,16). This mutant lacked rotenone-sensitive complex I activity.…”

“…Only a few of these accessory proteins, e.g. the acyl-carrier protein SDAP and the AQDQ and MWFE subunits from Neurospora crassa and mammals have been studied in more detail (3)(4)(5). The orthologue of the mammalian MWFE in N. crassa was identified recently (6).…”

“…Previous studies from this laboratory have characterized a Chinese hamster mutant cell completely deficient in the MWFE subunit (encoded by the X-linked NDUFA1 gene) (3,4,16). This mutant lacked rotenone-sensitive complex I activity.…”

Developmental competence in oocytes and cumulus cells: candidate genes and networks

“…Two mitochondrial proteins are downregulated, a component of the respiratory chain complex I -Ndufa1 [Au et al 1999] and the methyl transferase Shmt2 (UniProt: P34897). Two genes, Prkg1 (UniProt: Q6P5T7) and Tmsb10 (UniProt: P63313), are linked to cytoskeletal reorganization.…”