Cooperative regulation of the Vibrio vulnificus nan gene cluster by NanR protein, cAMP receptor protein, and N-acetylmannosamine 6-phosphate

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Title
Cooperative regulation of the Vibrio vulnificus nan gene cluster by NanR protein, cAMP receptor protein, and N-acetylmannosamine 6-phosphate
Author(s)
B S Kim; Jungwon HwangMyung Hee Kim; S H Choi
Bibliographic Citation
Journal of Biological Chemistry, vol. 286, no. 47, pp. 40889-40899
Publication Year
2011
Abstract
The nan cluster of Vibrio vulnificus, a food-borne pathogen, consists of two divergently transcribed operons, nanTPSLAR and nanEK nagA, required for transport and catabolism of N-acetylneuraminic acid (Neu5Ac). A mutation of nanR abolished the extensive lag phase observed for the bacteria growing on Neu5Ac and increased transcription of nanTP and nanE, suggesting that NanR is a transcriptional repressor of both nan operons. Intracellular accumulation of Neu5Ac was dependent on the carbon source, implying that the nan operons are also subject to catabolite repression. Hence, cAMP receptor protein (CRP) appeared to activate and repress transcription of nanTPSLAR and nanEK nagA, respectively. Direct bindings of NanR and CRP to the nanTP-nanE intergenic DNA were demonstrated by EMSA. Two adjacent NanR-binding sites centered at +44.5 and -10 and a CRP-binding site centered at -60.5 from the transcription start site of nanTP were identified by DNase I protection assays. Mutagenesis approaches, in vitro transcription, and isothermal titration calorimetry experiments demonstrated that N-acetylmannosamine 6-phosphate specifically binds to NanR and functions as the inducer of the nan operons. The combined results propose a model in which NanR, CRP, and N-acetylmannosamine 6-phosphate cooperate for precise adjustment of the expression level of the V. vulnificus nan cluster.
ISSN
0021-9258
Publisher
Amer Soc Biochemistry Molecular Biology Inc
DOI
http://dx.doi.org/10.1074/jbc.M111.300988
Type
Article
Appears in Collections:
Division of Biomedical Research > Microbiome Convergence Research Center > 1. Journal Articles
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