集胞藻PCC6803 中relA/spoT 同源基因syn-rsh (slr1325)的鉴定

Characterization of the relA/spoT homologue slr1325 ( synrsh) of the cyanobacterium Synechocystis sp.PCC6803

摘要:

摘要:【目的】四磷酸或五磷酸鸟苷(Guanosine 3'，5'-bispyrophosphate，( p) ppGpp) 是细菌在遭遇环境胁迫时细胞产生应激反应的信号分子，( p) ppGpp 由其合成酶RelA 或具有合成酶或水解酶双重催化功能的RelA/SpoT 合成。本文证明了集胞藻PCC6803 ( Synechocystis sp．) 中唯一编码RelA / SpoT 同源蛋白( 命名为Syn-RSH) 的基因slr1325( syn-rsh) 的功能。【方法】通过互补试验证明syn-rsh

关键词:关键词: 集胞藻PCC6803，syn-rsh(slr1325) ，(p) ppGpp，RelA/SpoT 同源蛋白

Abstract:

Abstract:［Objective］ Nucleotide guanosine-3'，5'-( bis) pyrophosphate ( ppGpp ) synthesized by ( ppGpp ) synthesase RelA or bifunctional ppGpp synthase / degradase RelA / SpoT，mediates bacterial stringent response to various stressful conditions． Here we characterized the slr1325 ( syn-rsh ) gene encoding a RelA / SpoT homolog ( Syn-RSH ) of the cyanobacterium Synechocystis sp． PCC6803． ［Methods］We performed phenotypic complement test using Escherichia coli strain with( p) ppGpp-synthesis defect to determine Syn-RSH function( s) ，and employed chromatographic analysis of32 Plabeled cellular mononucleotides to detect the accumulation of ppGpp in Escherichia coli strains expressing Syn-RSH and in Synechocystis sp． PCC6803． ［Results］ Syn-RSH expression in E． coli relA / spoT double mutant was able to restore the cell growth arrest; Chromatographic analysis of32 P-labeled cellular mononucleotides revealed that Syn-RSH expression resulted in the synthesis of ppGpp in E． coli strain with relA and spoT mutant mutation． Additionally，Synechocystis cells accumulated a low level of ppGpp under laboratory growth conditions． ［Conclusion］Syn-RSH possesses ppGpp synthase /degradase activities，and ppGpp is required for Synechocystis cell viability under normal growth conditions．

Key words:Keywords: Synechocystis sp．PCC6803，slr1325(syn-rsh)，(p) ppGpp，(p) ppGpp synthase / degradase