The copper-deprivation stimulon of Corynebacterium glutamicum comprises proteins for biogenesis of the actinobacterial cytochrome bc1- aa3 supercomplex

J Biol Chem. 2018 Oct 5;293(40):15628-15640. doi: 10.1074/jbc.RA118.004117. Epub 2018 Aug 28.

Abstract

Aerobic respiration in Corynebacterium glutamicum involves a cytochrome bc1-aa3 supercomplex with a diheme cytochrome c1, which is the only c-type cytochrome in this species. This organization is considered as typical for aerobic Actinobacteria. Whereas the biogenesis of heme-copper type oxidases like cytochrome aa3 has been studied extensively in α-proteobacteria, yeast, and mammals, nothing is known about this process in Actinobacteria. Here, we searched for assembly proteins of the supercomplex by identifying the copper-deprivation stimulon, which might include proteins that insert copper into cytochrome aa3 Using gene expression profiling, we found two copper starvation-induced proteins for supercomplex formation. The Cg2699 protein, named CtiP, contained 16 predicted transmembrane helices, and its sequence was similar to that of the copper importer CopD of Pseudomonas syringae in the N-terminal half and to the cytochrome oxidase maturation protein CtaG of Bacillus subtilis in its C-terminal half. CtiP deletion caused a growth defect similar to that produced by deletion of subunit I of cytochrome aa3, increased copper tolerance, triggered expression of the copper-deprivation stimulon under copper sufficiency, and prevented co-purification of the supercomplex subunits. The secreted Cg1884 protein, named CopC, had a C-terminal transmembrane helix and contained a Cu(II)-binding motif. Its absence caused a conditional growth defect, increased copper tolerance, and also prevented co-purification of the supercomplex subunits. CtiP and CopC are conserved among aerobic Actinobacteria, and we propose a model of their functions in cytochrome aa3 biogenesis. Furthermore, we found that the copper-deprivation response involves additional regulators besides the ECF sigma factor SigC.

Keywords: Actinobacteria; CopC; CtiP; complex; copper; copper starvation; cytochrome aa3; cytochrome c; cytochrome oxidase; protein assembly; respiration; respiratory chain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aerobiosis / genetics
  • Amino Acid Sequence
  • Bacillus subtilis / enzymology
  • Bacillus subtilis / genetics
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Cations, Divalent
  • Copper / metabolism*
  • Corynebacterium glutamicum / enzymology
  • Corynebacterium glutamicum / genetics*
  • Cytochromes c1 / genetics
  • Cytochromes c1 / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Electron Transport Complex III / genetics
  • Electron Transport Complex III / metabolism*
  • Electron Transport Complex IV / genetics
  • Electron Transport Complex IV / metabolism*
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Gene Expression Regulation, Bacterial*
  • Protein Multimerization
  • Pseudomonas syringae / enzymology
  • Pseudomonas syringae / genetics
  • Sigma Factor / genetics
  • Sigma Factor / metabolism

Substances

  • Bacterial Proteins
  • Cations, Divalent
  • CopC protein, Bacteria
  • DNA-Binding Proteins
  • Sigma Factor
  • sigC protein, Bacteria
  • Copper
  • Cytochromes c1
  • Electron Transport Complex IV
  • Electron Transport Complex III