Genome Sequence of Klebsiella oxytoca M5al, a Promising Strain for Nitrogen Fixation and Chemical Production.
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ABSTRACT:
SUBMITTER: Bao G
PROVIDER: S-EPMC3569362 | biostudies-literature | 2013 Jan
REPOSITORIES: biostudies-literature
Publications
Genome Sequence of Klebsiella oxytoca M5al, a Promising Strain for Nitrogen Fixation and Chemical Production.
Bao Guanhui G Zhang Yanping Y Du Chenyu C Chen Zugen Z Li Yin Y Cao Zhu'an Z Ma Yanhe Y
Genome announcements 20130131 1
Klebsiella oxytoca is an important microorganism for nitrogen fixation and chemical production. Here, we report an annotated draft genome of K. oxytoca strain M5al that contains 5,256 protein-coding genes and 95 structural RNAs, which provides a genetic basis for a better understanding of the physiology of this species. ...[more]
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Project description:Klebsiella oxytoca can assimilate nitrate and nitrite by using enzymes encoded by the nasFEDCBA operon. Expression of the nasF operon is controlled by general nitrogen regulation (Ntr) via the NtrC transcription activator and by pathway-specific nitrate and nitrite induction via the NasR transcription antiterminator. This paper reports our analysis of nasR gene expression. We constructed strains bearing single-copy Phi(nasR-lacZ) operon fusions within the chromosomal rhaBAD-rhaSR locus. The expression of DeltarhaBS::[Phi(nasR-lacZ)] operon fusions was induced about 10-fold during nitrogen-limited growth. Induction was reduced in both ntrC and rpoN null mutants, indicating that Ntr control of nasR gene expression requires the NtrC and sigma(N) (sigma(54)) proteins. Sequence inspection of the nasR control region reveals an apparent sigma(N)-dependent promoter but no apparent NtrC protein binding sites. Analysis of site-specific mutations coupled with primer extension analysis authenticated the sigma(N)-dependent nasR promoter. Fusion constructs with only about 70 nucleotides (nt) upstream of the transcription initiation site exhibited patterns of beta-galactosidase expression indistinguishable from Phi(nasR-lacZ) constructs with about 470 nt upstream. Expression was independent of the Nac protein, implying that NtrC is a direct activator of nasR transcription. Together, these results indicate that nasR gene expression does not require specific upstream NtrC-binding sequences, as previously noted for argT gene expression in Salmonella typhimurium (G. Schmitz, K. Nikaido, and G. F.-L. Ames, Mol. Gen. Genet. 215:107-117, 1988).
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