蓝细菌6803中糖基转移酶Sll1466对胁迫响应及其对糖基化、磷酸化反应的调控作用(英文)

Sll1466, a Glycosyl Transferase Homolog Involved in Stress Response and Regulation of Phosphorylation and Glycosylation Reactions in Synechocystis PCC 6803

糖基转移酶存在于原核和真核生物中,参与低聚糖和多糖的生物合成,在生物转化过程中起着重要的作用.本研究中我们去除了Synechocystis PCC 6803中的糖基转移酶基因sll1466.在不同培养基的光合自养条件下,Sll1466缺失突变体较野生型的细胞内部结构变化明显(超薄电镜观察),突变体在缺碳培养基条件下羧酶体含量比野生型高,并且在0.5 mol/L NaCl条件下的肝醣含量也明显高于野生型.突变体在不同光密度生长条件下的吸收光谱与野生型差异明显.分子水平上,突变体较野生型显现出如下3个方面的差异:a.2个碳水化合物选择性OprB孔蛋白在类囊体膜上发生糖基化;b.核杆连接蛋白CpcG1(Slr2051)在类囊体膜的上清中发生磷酸化;c.与上述表型差异相关的基因的转录水平亦呈现相同的变化趋势.这些结果预示着Sll1466在调控蓝细菌6803生理、代谢及能量转化等方面有着重要作用.

Glycosyltransferases are involved in the biosynthesis of oligosaccharides and polysaccharides.They are presented in both prokaryotes and eukaryotes,and play significant roles in biological processes.We deleted the glycosyltransferase homologue gene,sll1466,from Synechocystis PCC 6803.Thin-section electron micrographs showed that the mutant Synechocystis contained more carboxysomes when grown in the absence of CO 3 2and while more glycogen granules when grown in the presence of 0.5 mol/L NaCl than the wild type Synechocystis.Absorption spectra of the mutant grown under different light intensities differed significantly from wild type Synechocystis.At the molecular level,the mutant differed from the wild type in 3 aspects：（1） glycosylation of two carbohydrate-selective OprB porins in the thylakoid membrane;（2） phosphorylation of the rod-core linker,CpcG1（Slr2051）,in the supernatant of the thylakoid membrane;and（3） transcriptional variations of genes related to the above changes.These results suggested a profound role for Sll1466 in regulating physiology,metabolism,and energy transfer.