| Summary: | 碩士 === 國立中興大學 === 生物化學研究所 === 98 === At initiation of cell division, FtsZ, a tubulin-like protein, will polymerize into a Z-ring structure at the mid-cell. Z-ring provides a cytoskeletal scaffold that recruits other division proteins and some of which possess positive or negative regulation for Z-ring formation. EzrA is one of the division proteins and has a negative role for FtsZ polymerization; it inhibits aberrant Z-rings from assembling in cell poles and thus cytokinesis is restricted to mid-cell. In addition to the negative role, several studies have been proposed that EzrA also has a positive role in cytokinesis. Those studies found that either the null mutation or the conserved QNR patch mutation in ezrA or deficiency in EzrA, all these mutations make the cell length of mutant cells longer than that of wild type. According to the above evidences, EzrA is thought that it could maintain the dynamic nature of medial Z-ring, thereby renders Z-ring sensitive to coordinate between cell growth and cell division. The aim of this study is to understand which amino acid residues of EzrA are able to interact with FtsZ, to either inhibit its polymerization or to maintain its assembly dynamics with Z-ring. We make use of a serial EzrA deletion mutation for analysis and observe the phenotype of these mutants. We discovered that 52 amino acid residues (511-562) on C terminal of EzrA might have regulated for the dynamic nature of Z-ring except known QNR patch (505-511). Besides, all ezrA mutations results in delay of membrane formation between the dividing cells and chromosomes. However, where this delay is a result of defective Z-ring constriction by ezrA mutation remains to be answered.
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