Abstract
Cyanobacteria have a high nitrogen-to-carbon ratio (~0.2) and invest a lot of energy in nitrogen assimilation. Regulation of gene expression in response to changes in nitrogen availability therefore comprises an important part of environmental adaptation of cyanobacteria; Many genes involved in acquisition and assimilation of nitrogen are regulated by NtcA, a global nitrogen regulator. To identify new nitrogen-regulated genes and to gain a deeper insight into global nitrogen regulation in Synechococcus elongates, we used the high-density DNA microarray of S. elongates PCC 6301. Transfer of ammonium-grown cells to nitrate-containing medium induced many genes in addition to the known nitrogen-regulated genes such as nirA operon, cyanase operon, and the glutamine synthetase and ammonium transporter genes. By contrast, many of the CO2 assimilation genes were found to be downregulated. We are currently analyzing the contribution of NtcA to the global change in gene expression.
