Initiation of chromosomal DNA replication which is stimulated without oversupply of DnaA protein in Escherichia coli

Tsutomu Katayama, Toshio Nagata

研究成果: Contribution to journalArticle査読

19 被引用数 (Scopus)

抄録

The temperature-sensitive dnaA46 mutation in Escherichia coli can be phenotypically suppressed at 42° C by oversupply of GroELS proteins, and the suppressed cells grow extremely slowly at 30° C. We found that the phenotype of dnaA46 showing this cold sensitivity was dominant over the phenotype of dnaA+, and could not be rescued by introduction of oriC-independent replication systems. These results suggest that the cold sensitivity was not caused by a simple defect in replication. When a growing culture of a dnaA46 strain with a GroELS-overproducing plasmid was shifted from 42° to 30° C in the presence of chloramphenicol, the chromosomal DNA replicated excessively. Initiation of replication occurred at the site of oriC repeatedly four or five times during a 4 h incubation period without concomitant protein synthesis, indicating an excessive capacity for initiation. Such overreplication did not take place at 42° C in the suppressed dnaA46 strain, or at either temperature in GroELS-oversupplied dnaA+ cells. No significant difference was detected between the cellular content of DnaA protein in suppressed cells where the initiation capacity was abnormally high, and that in wild-type cells in which the initiation capacity was normal. Thus, DnaA protein might function in vivo through some phase control mechanism for initiation, apart from a simple regulation by its total amount. A possible mechanism is proposed based on the participation of GroELS proteins in protein folding.

本文言語英語
ページ(範囲)491-502
ページ数12
ジャーナルMGG Molecular & General Genetics
226
3
DOI
出版ステータス出版済み - 5 1 1991
外部発表はい

All Science Journal Classification (ASJC) codes

  • 遺伝学

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