CtaG is required for formation of active cytochrome c oxidase in Bacillus subtilis.
The Gram-positive bacterium Bacillus subtilis contains two respiratory oxidases of the haem-copper superfamily: cytochrome aa(3), which is a quinol oxidase, and cytochrome caa(3), which is a cytochrome c oxidase. Cytochrome c oxidase uniquely contains a di-copper centre, Cu(A). B. subtilis CtaG is a membrane protein encoded by the same gene cluster as that which encodes the subunits of cytochrome c oxidase. The role of B. subtilis CtaG and orthologous proteins present in many other Gram-positive bacteria has remained unexplored. The sequence of CtaG is unrelated to that of CtaG/Cox11p of proteobacteria and eukaryotic cells. This study shows that B. subtilis CtaG is essential for the formation of active cytochrome caa(3) but is not required for assembly of the core subunits I and II with haem in the membrane and it has no role in the synthesis of active cytochrome aa(3). B. subtilis YpmQ, a homologue to Sco1p of eukaryotic cells, is also a membrane-bound cytochrome c oxidase-specific assembly factor. Properties of CtaG- and YpmQ-deficient mutants were compared. Cells lacking YpmQ showed a low cytochrome c oxidase activity and this defect was suppressed by the supplementation of the growth medium with copper ions. It has previously been proposed that YpmQ/Sco1p is involved in synthesis of the Cu(A) centre. The results of this study are consistent with this proposal but the exact role of YpmQ in assembly of cytochrome c oxidase remains to be elucidated.
Bengtsson
Jenny
J
Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-22362 Lund, Sweden.
von Wachenfeldt
Claes
C
Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-22362 Lund, Sweden.
Winstedt
Lena
L
Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-22362 Lund, Sweden.
Nygaard
Per
P
Department of Biological Chemistry, University of Copenhagen, Solvgade 83, DK-1307 Copenhagen K, Denmark.
Hederstedt
Lars
L
Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-22362 Lund, Sweden.
D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D045264:Cytochromes a / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D016296:Mutagenesis; D010957:Plasmids; D021122:Protein Subunits / Q000235:genetics; D015183:Restriction Mapping; D013053:Spectrophotometry
D001426:Bacterial Proteins; D008565:Membrane Proteins; D021122:Protein Subunits; D045264:Cytochromes a; D003576:Electron Transport Complex IV