Hu Yong, Kong Dong-Dong, Wang Dong, He Yi-Kun
Department of Biology, Capital Normal University, Beijing 100037, China.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai). 2003 Nov;35(11):998-1004.
FtsZ protein plays a key role in the division of bacteria and chloroplast. To investigate the evolution of the chloroplast dividing apparatus, cloning and molecular characterization of a second chloroplast division gene, CrFtsZ3, from Chlamydomonas reinhardtii is performed. As there are two ftsZ genes in Chlamydomonas reinhardtii, duplication and divergence of the ftsZ genes might occur in an early stage before the emergence of green algae during the course of plant evolution. Sequence analysis showed that CrFtsZ3 gene had significant sequence homology with other ftsZs. It encoded a precursor of 479 amino acid residues with a putative transit peptide in its N-terminal. To study the function of CrFtsZ3, a recombinant plasmid expressing the full length CrFtsZ3/EGFP fusion protein was constructed. By using IPTG inducing, overexpression of CrFtsZ3/EGFP in E.coli was achieved, and this overexpression blocked cell division and resulted in filament formation. GFP-derived fluorescence showed regularly spaced dots along the bacterial filaments. This suggests that CrFtsZ3 could still recognize the signals of cell division site in E.coli and could take part in the process of bacterial division.
FtsZ蛋白在细菌和叶绿体的分裂过程中起着关键作用。为了研究叶绿体分裂装置的进化，我们从莱茵衣藻中克隆并对第二个叶绿体分裂基因CrFtsZ3进行了分子特征分析。由于莱茵衣藻中有两个ftsZ基因，在植物进化过程中，ftsZ基因的复制和分化可能在绿藻出现之前的早期阶段就已经发生。序列分析表明，CrFtsZ3基因与其他ftsZ具有显著的序列同源性。它编码一个由479个氨基酸残基组成的前体，其N端有一个假定的转运肽。为了研究CrFtsZ3的功能，构建了表达全长CrFtsZ3/EGFP融合蛋白的重组质粒。通过IPTG诱导，在大肠杆菌中实现了CrFtsZ3/EGFP的过表达，这种过表达阻断了细胞分裂并导致丝状形成。GFP衍生的荧光沿着细菌丝呈现规则间隔的点。这表明CrFtsZ3仍然可以识别大肠杆菌中细胞分裂位点的信号，并可以参与细菌分裂过程。
