Abstract

The metK gene of Escherichia coli encodes S-adenosylmethionine synthetase, which catalyzes the biosynthesis of S-adenosylmethionine (SAM), the primary methyl group donor. A partial defect in metK expression caused by a point mutant in its promoter leads to a decrease in the cellular SAM concentration, resulting in a block in cell division. Thus metK mutants form filaments with regularly distributed nucleoids. This thesis aims to find out the division step at which cell division process stops. Herein I examine localization of 8 division proteins in metK84 filaments. The results show that early division proteins, FtsZ, FtsA and ZipA, are able to establish themselves in the septum, while the late proteins, FtsQ, FtsW, FtsI and FtsN, fail to localize. FtsK localizes to the septum at some extent, but the result is uncertain. Further study of FtsK localization in metK84 filaments is required. This localization study suggests that metK84 filamentation is caused by the failure of FtsQ or FtsK to localize to the septum during the cell division process.