Transcriptional analysis of the multicopy hao gene coding for hydroxylamine oxidoreductase in Nitrosomonas sp. strain ENI-11.
The nitrifying bacterium Nitrosomonas sp. strain ENI-11 has three copies of the gene encoding hydroxylamine oxidoreductase (hao(1), hao(2), and hao(3)) on its genome. Broad-host-range reporter plasmids containing transcriptional fusion genes between hao copies and lacZ were constructed to analyze the expression of each hydroxylamine oxidoreductase gene (hao) copy individually and quantitatively. beta-Galactosidase assays of ENI-11 harboring reporter plasmids revealed that all hao copies were transcribed in the wild-type strain. Promoter analysis of hao copies revealed that transcription of hao(3) was highest among the hao copies. Expression levels of hao(1) and hao(2) were 40% and 62% of that of hao(3) respectively. Transcription of hao(1) was negatively regulated, whereas a portion of hao(3) transcription was read through transcription from the rpsT promoter. When energy-depleted cells were incubated in the growth medium, only hao(3) expression increased. This result suggests that it is hao(3) that is responsible for recovery from energy-depleted conditions in Nitrosomonas sp. strain ENI-11.
Hirota
Ryuichi
R
Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University.
Kuroda
Akio
A
Ikeda
Tsukasa
T
Takiguchi
Noboru
N
Ohtake
Hisao
H
Kato
Junichi
J
D004269:DNA, Bacterial / Q000737:chemistry; D018628:Gene Dosage; D009606:Nitrosomonas / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D010088:Oxidoreductases / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D013045:Species Specificity; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D010088:Oxidoreductases; C021401:hydroxylamine dehydrogenase