Analysis of the possible interaction between FtsA and EzrA in regulation of Bacillus subtilis cell division

• Main Authors: Ying-Chun Wang, 王瀅淳
• Other Authors: 張邦彥
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/07297905007619102331

碩士 === 國立中興大學 === 生物化學研究所 === 97 === The process of cell division is tightly regulated to ensure that both daughter cells inherit complete genomes and are of appropriate size and shape. In the initiation of Bacillus subtilis cell division, FtsZ polymerizes at the midcell into a ring structure called Z ring. Z ring formation is required for subsequent assembly of the cell division machinery. FtsA is a positive regulator that promotes Z ring stability and recruits downstream components of the cell division machinery to the Z ring. EzrA is a negative regulator of Z ring formation. Loss of EzrA results in cells with multiple FtsZ rings located at polar as well as medial sites and reduces the critical concentration of FtsZ required for ring formation. EzrA also participates in efficient cell division. The cell length of B. subtilis is increased when the expression level of EzrA is decreased. EzrA also maintains a proper FtsZ assembly dynamics within the medial FtsZ ring, thereby renders Z ring sensitive to factors responsible for coordinating cell growth and cell division. The aim of this study is to understand whether there is a direct interaction between FtsA and EzrA, and whether this interaction affect the ATPase activity of FtsA, which is important to the dynamic equilibrium between Z ring and free FtsZ. Immunoprecipitation of the B. subtilis cell extract with anti-FtsA and anti-EzrA after formaldehyde croslinking suggested that FtsA and EzrA are in a same protein complex, although the signal of FtsA was shielded by Protein A in Western blot. In vitro immunoprecipitation with purified FtsA and EzrA revealed that EzrA and FtsA are able to directly interact with each other. However, nonspecific interaction between FtsA and some of the negative control proteins were also observed. Since EzrA did not affect the ATPase activity of FtsA to a detectable level, we think that further investigations are required to answer whether EzrA is able to coordinate the dynamic equilibrium between Z ring and free FtsZ by interacting with FtsA.