1887

Abstract

In the unicellular cyanobacterium sp. PCC 7942, ammonium/methylammonium transport activity has been characterized but ammonium transport genes have not been described. The gene encoding a permease responsible for high-affinity [C]methylammonium transport in sp. PCC 7942 was cloned and inactivated. The Amt1 permease appeared essential to take up ammonium when it was present at low concentrations in the external medium and might also be involved in recapture of ammonium leaked out from the cells. Expression of , which was induced in the absence of ammonium and also influenced by the inorganic carbon supply, was dependent on the NtcA transcriptional regulator. The promoter of was found to exhibit the structure of NtcA-activated promoters, and specific binding of purified NtcA to promoter sequences was observed. The results of this study indicate that belongs to the NtcA regulon and that NtcA may respond to both nitrogen and carbon availability.

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2002-03-01
2019-10-15
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