Characterization of YpmQ, an Accessory Protein Required for the Expression of Cytochrome c Oxidase in Bacillus subtilis

Abstract

A search of the Bacillus subtilis genome identifies a potential homolog, ypmQ, of the inner mitochondrial membrane protein Sco1 from yeast. Sco1 has been found to aid the delivery of copper to cytochrome c oxidase. B. subtilis expresses two members of the cytochrome oxidase family, a cytochrome c oxidase that has two copper centers, Cu A and Cu B , and a menaquinol oxidase that has only Cu B . Deletion of ypmQ in B. subtilis depresses expression of cytochrome c oxidase but not menaquinol oxidase. Levels of cytochrome c oxidase recover when copper is added to the growth medium of the ⌬ypmQ strain or when ypmQ is expressed from a plasmid. Neither treatment affects the amount or activity of menaquinol oxidase. YpmQ in which two conserved cysteines are replaced by serines and a conserved histidine is replaced by alanine do not complement the deletion of ypmQ even though these mutant forms are found in the membrane extract at a level similar to the wild type protein. We propose that the two cysteines and the histidine are critical for the function of YpmQ and suggest they are involved in copper exchange between YpmQ and the Cu A site of cytochrome c oxidase.

Regulation of the aerobic respiratory chain in the facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense

“…The role of this protein is less clear, but available evidence indicates it is part of sensory transducing pathway (Buggy & Bauer, 1995;Eraso & Kaplan, 1995, 2000Masuda et al, 1999). In the mitochondria of Saccharomyces cerevisiae, and in Bacillus subtilis, Sco1 (S. cerevisiae) and YpmQ (B. subtilis) is required for biogenesis of the Cu A centre of cytochrome c oxidase (Schulze & Rödel, 1989;Rentzsch et al, 1999;Mattatall et al, 2000). Thus, the function of PoxJ in P. oguniense, which is expressed under both aerobic and anaerobic conditions and has Cu(I)-binding residues, is still in question.…”

CsoR regulates the copper efflux operon copZA in Bacillus subtilis

“…Copper is an essential element for Bacillus subtilis aerobic respiration because it is a cofactor for haem-copper oxidases, the terminal enzymes in the respiratory pathway (Mattatall et al, 2000). The pathways responsible for the uptake of copper are not yet defined, but copper present in the cytosol appears to be tightly chaperoned.…”

A copper(I) protein possibly involved in the assembly of Cu A center of bacterial cytochrome c oxidase

“…The repeated occurrence of genes in each other's neighborhood in bacterial genomes has been shown to indicate a functional association between the proteins they encode, i.e., the proteins are involved in the same biochemical pathway (5,6). Following this approach, we have analyzed the gene neighborhood of a bacterial protein, Sco1, which is proposed to be involved in copper ion delivery to the Cu A center of cytochrome c oxidase (CcO) complex (7), with the purpose to locate new proteins potentially involved in copper delivery and insertion in this enzyme. There is a large variability in proteins involved in copper delivery to CcO.…”