抄録
Cyanobacterial PII protein is modified by phosphorylation/dephosphorylation in response to the cellular nitrogen status. Formerly, we found high-level expression of the ammonium assimilation genes in a PII-deficient mutant of Synechocystis sp. PCC 6803 and proposed the presence of a hitherto unknown mechanism that specifically regulates the ammonium assimilation genes. In this study, to further investigate this mechanism, we examined the ammonium assimilation activity of the PII-deficient mutant. It was found that the PII-deficient mutant grows much slower than the wild-type strain on ammonium under the conditions of high light and glucose supplementation. The rate of ammonium assimilation increased under these conditions in the wild-type strain but not in the PII-deficient mutant. These results suggested that the ammonium assimilation activity is upregulated by high light and glucose in the wild-type Synechocystis strain in a PII-dependent manner.
