Abstract
We previously identified a protein that bound specifically to the promoter region of the groESL gene in Synechococcus sp. PCC 7002 and termed it Shl-1. The amino acid sequence contains a Nudix motif, which is specific to a family of Nudix hydrolase that hydrolyzes nucleoside diphosphate derivatives. Shl-1, which was overexpressed in E. coli and purified, hydrolyzed ADP-ribose exclusively among various nucleoside diphosphate derivatives, such as NADH, ATP and GTP. Since free ADP-ribose, a major metabolic product of NAD+, is harmful for the cell, Shl-1 might control its level. We disrupted the shl-1 gene in Synechococcus to examine its role as a Nudix hydrolase in vivo and also to clarify whether Shl-1 might regulate the expression of the groESL gene. A homologous gene with undefined functions is present in the genome of Synechocystis sp. PCC 6803. The product of this gene also hydrolyzed ADP-ribose.
