Zhang C C, Huguenin S, Friry A
Ecole Supérieure de Biotechnologie de Strasbourg, Université Louis Pasteur de Strasbourg, Illkirch, France.
Res Microbiol. 1995 Jul-Aug;146(6):445-55. doi: 10.1016/0923-2508(96)80290-7.
Heterocysts, cells specialized in nitrogen fixation in Anabaena sp. PCC 7120, lose the potential for cell division once fully differentiated. This suggests that cell division activity is differentially regulated in heterocysts and vegetative cells. FtsZ has been shown to play a crucial role in bacterial cell division. Two degenerate oligonucleotide primers were designed to detect, by polymerase chain reaction (PCR), an ftsZ homologue from the heterocystous cyanobacterium Anabaena sp. PCC 7120. A PCR-amplified DNA fragment was cloned and used as a probe to isolate the entire ftsZ gene of Anabaena sp. PCC 7120. The deduced amino acid sequence shares strong similarities with other FtsZ proteins, suggesting remarkable conservation of the FtsZ protein during evolution. An ORF downstream of ftsZ, which would be transcribed in the opposite direction compared to ftsZ, could encode a polypeptide with significant sequence similarity to the glutathione synthetase from Escherichia coli. Inactivation experiments in vivo for both ftsZ and the glutathione synthetase gene did not yield any double recombinants either in the presence or in the absence of combined nitrogen, suggesting that both genes are essential for cell growth under these conditions.
异形胞是鱼腥藻PCC 7120中专门用于固氮的细胞，一旦完全分化就失去了细胞分裂的潜力。这表明细胞分裂活动在异形胞和营养细胞中受到不同的调节。FtsZ已被证明在细菌细胞分裂中起关键作用。设计了两个简并寡核苷酸引物，通过聚合酶链反应（PCR）从异形胞蓝藻鱼腥藻PCC 7120中检测ftsZ同源物。将PCR扩增的DNA片段克隆并用作探针，以分离鱼腥藻PCC 7120的整个ftsZ基因。推导的氨基酸序列与其他FtsZ蛋白具有很强的相似性，表明FtsZ蛋白在进化过程中具有显著的保守性。ftsZ下游的一个开放阅读框（ORF），其转录方向与ftsZ相反，可能编码一种与大肠杆菌谷胱甘肽合成酶具有显著序列相似性的多肽。ftsZ和谷胱甘肽合成酶基因的体内失活实验在有或没有化合态氮的情况下均未产生任何双重组体，这表明这两个基因在这些条件下对细胞生长都是必不可少的。
