Affiliation:
1. School of Biological Sciences, University of Manchester, Manchester, United Kingdom
2. Institute of Cell and Molecular Biology, University of Edinburgh, Edinburgh, Scotland
3. Department of Biology, American University of Beirut, Beirut, Lebanon
Abstract
ABSTRACT
We isolated five new temperature-sensitive alleles of the essential cell division gene
ftsZ
in
Escherichia coli
, using P1-mediated, localized mutagenesis. The five resulting single amino acid changes (Gly
109
→Ser
109
for
ftsZ6460
, Ala
129
→Thr
129
for
ftsZ972
, Val
157
→Met
157
for
ftsZ2066
, Pro
203
→Leu
203
for
ftsZ9124
, and Ala
239
→Val
239
for
ftsZ2863
) are distributed throughout the FtsZ core region, and all confer a lethal cell division block at the nonpermissive temperature of 42°C. In each case the division block is associated with loss of Z-ring formation such that fewer than 2% of cells show Z rings at 42°C. The
ftsZ9124
and
ftsZ6460
mutations are of particular interest since both result in abnormal Z-ring formation at 30°C and therefore cause significant defects in FtsZ polymerization, even at the permissive temperature. Neither purified FtsZ9124 nor purified FtsZ6460 exhibited polymerization when it was assayed by light scattering or electron microscopy, even in the presence of calcium or DEAE-dextran. Hence, both mutations also cause defects in FtsZ polymerization in vitro. Interestingly, FtsZ9124 has detectable GTPase activity, although the activity is significantly reduced compared to that of the wild-type FtsZ protein. We demonstrate here that unlike expression of
ftsZ84
, multicopy expression of the
ftsZ6460
,
ftsZ972
, and
ftsZ9124
alleles does not complement the respective lethalities at the nonpermissive temperature. In addition, all five new mutant FtsZ proteins are stable at 42°C. Therefore, the novel isolates carrying single
ftsZ
(Ts) point mutations, which are the only such strains obtained since isolation of the classical
ftsZ84
mutation, offer significant opportunities for further genetic characterization of FtsZ and its role in cell division.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
22 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献