中文摘要
蓝藻的异型胞分化是一个很好的研究格式形成的模式系统。HetR，CcbP，和钙离子浓度在这一分化过程中起着重要作用。针对胞内钙离子浓度上调机理，我们解析了钙结合蛋白CcbP 的三维结构，并基本了解了它如何调控细胞中钙离子浓度。成功构建了异型胞分化蓝藻的P-II突变株，发现中全新的PII修饰方式，同时证明PII同异型胞分化无关，但对于氮代谢有十分重要的作用。同芝加哥大学合作解析了HetR 蛋白的三维结构，证实HetR以同源二聚体形式结合DNA，并成功构建了可以在加氮素条件下分化异型胞的hetR突变株。发现一个普遍存在于厌氧生物，但在好氧生物非常少见的RbrA基因，对该基因的详细研究发现，RbrA是一个依赖FNR的过氧化物酶，在异型胞清除过氧化氢作用中起关键作用。同时还对Mn-Sod在鱼腥藻中的作用进行了详细研究。发现patA 表达受HetR调控而受PatS抑制，说明PatA参与异型胞分化的正调控网络。对MreB研究表明，MreB对蓝细菌细胞分裂并不重要，而对对细胞极性和形态发生有重要作用。我们还发现蓝细菌的染色体分离可能是依靠多拷贝染色体随机分离的方式进行。
英文摘要
Heterocyst differentiation is a unique model system for studying pattern formation in biological world. HetR, CcbP and intracellular calcium concentration play important role in heterocyst formation. To understand how calcium concentration is regulated, we obtained NMR solution structure of the calcium-binding protein CcbP, which shed light on how calcium concentration could be regulated. We obtained successfully a glnB mutant in a heterocystous cyanobacterium and our results showed that its product, PII, is modified through a unique modification. We also showed that PII is not required for heterocyst formation, but critical to nitrogen metabolism. By collaborating with University of Chicago, we have obtained a crystal structure of HetR, which confirmed that HetR is a DNA-binding homodimer. We also obtained a hetR mutant strain that forms heterocysts in the presence of combined nitrogen. We found that RbrA, a protein found mostly in anaerobic organisms, was a FNR-dependent peroxidase and it plays a very important role in protecting nitrogenase from oxygen damage. We also studied the roles of Mn-Sod in Anabaena. We found that patA is regulated by HetR and its expression was inhibited by PatS, indicating that PatA is a part of positive feedback circuit. Finally, we found that MreB was not critical to cell division
结题摘要
蓝藻的异型胞分化是一个很好的研究格式形成的模式系统。HetR，CcbP，和钙离子浓度在这一分化过程中起着重要作用。针对胞内钙离子浓度上调机理，我们解析了钙结合蛋白CcbP 的三维结构，并基本了解了它如何调控细胞中钙离子浓度。成功构建了异型胞分化蓝藻的P-II突变株，发现中全新的PII修饰方式，同时证明PII同异型胞分化无关，但对于氮代谢有十分重要的作用。同芝加哥大学合作解析了HetR 蛋白的三维结构，证实HetR以同源二聚体形式结合DNA，并成功构建了可以在加氮素条件下分化异型胞的hetR突变株。发现一个普遍存在于厌氧生物，但在好氧生物非常少见的RbrA基因，对该基因的详细研究发现，RbrA是一个依赖FNR的过氧化物酶，在异型胞清除过氧化氢作用中起关键作用。同时还对Mn-Sod在鱼腥藻中的作用进行了详细研究。发现patA 表达受HetR调控而受PatS抑制，说明PatA参与异型胞分化的正调控网络。对MreB研究表明，MreB对蓝细菌细胞分裂并不重要，而对对细胞极性和形态发生有重要作用。我们还发现蓝细菌的染色体分离可能是依靠多拷贝染色体随机分离的方式进行。