Cloning And Functional Research Of Scpats Gene And Schetr Gene In Cyanobacterium Schizothrix Calcicola

Filamentous cyanobacterium Anabaena sp. strain PCC 7120 is a model strain in the studies of cyanobacterium. patS and hetR are genes that play key roles in heterocyst development. In Anabaena PCC 7120, patS gene performs a function of repressing heterocyst differentiation and hetR gene performs a function of stimulating heterocyst differentiation. It is reported that these two genes also exist in the genomes of other non-heterocystous cyanobacterial strains. However, their functions in other cyanobacterial strains especially non-heterocystous strains remain unknown.Schizothrix calcicola is a non-heterocystous cyanobacterial strain, the genome of which has not been sequenced. Since hetR is a highly conserved gene, we designed degenerate primers to amplify the sequence of Schizothrix hetR. Chromosome walking technique was also utilized to clone the flanking sequences of Schizothrix hetR and a DNA sequence of 2893 bps was obtained. Via bioinformatics analysis, it was found that the sequence contains two ORFs. They were the homologues of Anabaena patS and hetR. Therefore, the two ORFs were nominated schetR and scpatS, respectively. To analyze the function of scpatS and schetR, the two genes were cloned and expressed in Anabaena sp. PCC 7120 strains since the genetic conjugation system of Schizothrix calcicola has not been established.The conclusion is that the homologues of Anabeana patS and hetR genes exist in the genome of non-heterocystous cyanobacterial strain Schizothrix calcicola. And schetR and scpatS showed the same effects on heterocyst development as their Anabaena counterparts did.