Cytochrome c oxidase contains an extra charged amino acid cluster in a new type of respiratory chain in the amino-acid-producing Gram-positive bacterium Corynebacterium glutamicum.
The membranes from Corynebacterium glutamicum cells contain a hydrophobic di-haem C protein as the cytochrome c subunit of the new type of cytochrome bc complex (complex III in the respiratory chain) encoded by the qcrCAB operon [Sone, N., Nagata, K., Kojima, H., Tajima, J., Kodera, Y., Kanamaru, T., Noguchi, S. & Sakamoto, J. (2001). Biochim Biophys Acta 1503, 279-290]. To characterize complex IV, cytochrome c oxidase and its structural genes were isolated. The oxidase is of the cytochrome aa(3) type, but mass spectrometry indicated that the haem is haem As, which contains a geranylgeranyl side-chain instead of a farnesyl group. The enzyme is a SoxM-type haem-copper oxidase composed of three subunits. Edman degradation and mass spectrometry suggested that the N-terminal signal sequence of subunit II is cleaved and that the new N-terminal cysteine residue is diacylglycerated, while neither subunit I nor subunit III is significantly modified. The genes for subunits II (ctaC) and III (ctaE) are located upstream of the qcrCAB operon, while that for subunit I (ctaD) is located separately. The oxidase showed low enzyme activity with extrinsic substrates such as cytochromes c from horse heart or yeast, and has the Cu(A)-binding motif in its subunit II. A prominent structural feature is the insertion of an extra charged amino acid cluster between the beta2 and beta4 strands in the substrate-binding domain of subunit II. The beta2-beta4 loop of this oxidase is about 30 residues longer than that of major cytochrome c oxidases from mitochondria and proteobacteria, and is rich in both acidic and basic residues. These findings suggest that the extra charged cluster may play a role in the interaction of the oxidase with the cytochrome c subunit of the new type of bc complex.
Sakamoto
Junshi
J
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka-ken 820-8502, Japan1.
Shibata
Takatsugu
T
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka-ken 820-8502, Japan1.
Mine
Tadashi
T
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka-ken 820-8502, Japan1.
Miyahara
Ryoko
R
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka-ken 820-8502, Japan1.
Torigoe
Tomokimi
T
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka-ken 820-8502, Japan1.
Noguchi
Shunsuke
S
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka-ken 820-8502, Japan1.
Matsushita
Kazunobu
K
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi, Yamaguchi 753-0841, Japan2.
Sone
Nobuhito
N
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka-ken 820-8502, Japan1.
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003352:Corynebacterium / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D005971:Glutamates / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA
D005971:Glutamates; D003576:Electron Transport Complex IV