Abstract
Pirin is a well-conserved protein among various organisms. It is involved in the process of apoptosis in human and tomato, whereas roles of its bacterial counterparts are totally unknown. We found that sll1773 encoding a Pirin homolog and ssl3389 encoding a putative transcriptional regulator are co-transcribed under stressed conditions in a cyanobacterium Synechocystis sp. PCC 6803. We named sll1773 and ssl3389, pirA and pirB, respectively. slr1871 encoding a LysR family transcriptional regulator located immediately upstream of pirAB in the divergent direction. Expression of pirAB was derepressed by disruption of slr1871 under non-stressed conditions, indicating that this gene works as a repressor of pirAB. Therefore, we named slr1871, pirR. Further investigation on the relationship between pirAB and pirR revealed that complicated interaction was observed between three genes in response to the changes in environmental conditions.
