Another multiheme protein, hydroxylamine oxidoreductase, abundantly produced in an anammox bacterium besides the hydrazine-oxidizing enzyme.
A hydroxylamine oxidoreductase (HAO) was purified from anammox sludge in which an anammox bacterium, strain KSU-1, was dominant. The enzyme was a 118-kDa homodimer composed of a 53-kDa subunit. With phenazine methosulfate and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide as electron acceptors, the V(max) and K(m) for hydroxylamine were determined as 9.6+/-0.2 micromol/min x mg and 33+/-2 microM, while those for hydrazine were 0.54+/-0.0 micromol/min x mg and 25+/-2 microM, respectively. The HAO had a P468 chromophore. These enzymatic properties were different from those of the hydrazine-oxidizing enzyme (HZO), a multiheme protein abundantly produced by the KSU-1 strain, but were similar to those of the HAO purified from Candidatus Brocadia anammoxidans. The hao gene exists upstream of the hzoB gene, which codes for the HZO. The sequence deduced from the hao gene indicated eight c-type heme binding motifs and showed 87% identity with a polypeptide encoded by an open reading frame (kustc1061) in the genome of an anammox bacterium Candidatus Kuenenia stuttgartiensis. These suggested that the HAO is an indispensable enzyme and well conserved in anammox bacteria, similar to the HZO. This enzyme might therefore be a specific hydroxylamine oxidoreductase for anammox bacteria.
Shimamura
Munetaka
M
Department of Applied Life Science, Faculty of Biotechnology and Life Science, Sojo University, 4-22-1 Ikeda, Kumamoto 860-0082, Japan.
Nishiyama
Takashi
T
Shinya
Kazutaka
K
Kawahara
Yuka
Y
Furukawa
Kenji
K
Fujii
Takao
T
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry; D019281:Dimerization; D000081062:Heme-Binding Proteins; D006420:Hemeproteins / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry; D008773:Methylphenazonium Methosulfate / Q000737:chemistry; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D012722:Sewage / Q000382:microbiology; D013379:Substrate Specificity; D013778:Tetrazolium Salts / Q000737:chemistry; D013844:Thiazoles / Q000737:chemistry
D001426:Bacterial Proteins; D000081062:Heme-Binding Proteins; D006420:Hemeproteins; D006834:Hydrazines; D012722:Sewage; D013778:Tetrazolium Salts; D013844:Thiazoles; C404449:heme protein, bacteria; C029424:hydrazine; D008773:Methylphenazonium Methosulfate; D010088:Oxidoreductases; C021401:hydroxylamine dehydrogenase; C022616:thiazolyl blue