Deficiency of essential GTP-binding protein ObgE in Escherichia coli inhibits chromosome partition

Kobayashi, G Moriya, S Wada, C

G. Kobayashi et al., Deficiency of essential GTP-binding protein ObgE in Escherichia coli inhibits chromosome partition, MOL MICROB, 41(5), 2001, pp. 1037-1051

58

INGLESE

Article

Microbiology

MOLECULAR MICROBIOLOGY

0950-382X → ACNP

41

5

2001

1037 - 1051

ISI

0950-382X(200109)41:5<1037:DOEGPO>2.0.ZU;2-H

GTP-binding proteins are involved in cell proliferation, development, signa l transduction, protein elongation, etc. and construct the GTPase superfami ly, whose structures and sequence motifs (G-1 to G-5) are highly conserved from prokaryote to eukaryote. Obg of Bacillus subtilis and Obg homologues o f other bacteria belong to the GTPase superfamily and have been suggested a s being essential for cell growth, development and monitoring of intracellu lar levels of GTP. We identified the Obg homologue in Escherichia coli, a p rotein previously known as YhbZ, which we have renamed ObgE. Double cross-o ver experiments showed that the obgE gene is essential for growth in E. col i. From characterization of the obgE temperature-sensitive mutant, we found that DNA replication was not inhibited, that the nucleoids did not partiti on and instead remained in the middle of cell, and that the cells elongated . Overproduction of ObgE also resulted in aberrant chromosome segregation. These data suggested that ObgE is involved directly or indirectly in E. col i chromosome partitioning. Characterization studies showed that ObgE is abu ndant in normal cells, partially associated with the membrane and does not associate with ribosomes such as in Obg of B. subtilis. We purified ObgE pr otein from a cell extract of E. coli, and the purified ObgE had GTPase acti vity and DNA-binding ability.