PlmA, a New Member of the GntR Family, Has Plasmid Maintenance Functions in Anabaena sp. Strain PCC 7120

摘要: The filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 maintains a genome that is divided into 6.4-Mb chromosome, three large plasmids of more 100 kb, two medium-sized 55 and 40 5.5-kb plasmid. Plasmid copy number can be dynamic in some cyanobacterial species, the genes regulate this process have not been characterized. Here we show mutations an open reading frame, all1076, reduce numbers copies per chromosome several plasmids. In mutant strain, pCC7120 are both reduced to less than 50% their wild-type levels. exogenous pDU1based plasmid pAM1691 25% its level, rapidly lost. peptide encoded by all1076 shows similarity members GntR family transcriptional regulators. Phylogenetic analysis reveals new domain topology within family. PlmA homologs, all coming from form subfamily distinct previously identified subfamilies. locus, named plmA, regulates maintenance functions 7120.