Effect of nitrate availability on expression of multi sensor histidine kinase gene in Spirulina platensis PCC 7345

Abstract

Addition of nitrate (NO −3 ) to a suspension of NO −3 -depleted Spirulina platensis PCC 7345 restored back the PSII reaction centre efficiency. Using RAPD/RT-PCR differential display, we have detected the upregulation of a novel gene in filaments starved of nitrogen when enriched with NO −3 . Semiquantitative RT-PCR clearly shows that NO −3 repletion induces the expression of this gene. Its nucleotide sequence is homologous to multi sensor histidine kinase (hstk) from Spirulina platensis NIES-39 and Spirulina maxima CS-328 genes. The open reading frame of this gene encodes a protein of 98 amino acids contains sensory domain of PAS domain.