Characterization of mutations affecting the Escherichia coli essential GTPase era that suppress two temperature-sensitive dnaG alleles

被引:46
作者
Britton, RA
Powell, BS
Court, DL
Lupski, JR
机构
[1] BAYLOR COLL MED,DEPT MOL & HUMAN GENET,HOUSTON,TX 77030
[2] BAYLOR COLL MED,CELL & MOL BIOL PROGRAM,HOUSTON,TX 77030
[3] BAYLOR COLL MED,DEPT PEDIAT,HOUSTON,TX 77030
[4] NCI,GENE REGULAT & CHROMOSOME BIOL LAB,ABL,BASIC RES PROGRAM,FREDERICK CANC RES & DEV CTR,FREDERICK,MD 21702
关键词
D O I
10.1128/jb.179.14.4575-4582.1997
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
Two suppressor mutations of the temperature-sensitive DNA primase mutant dnaG2903 have been characterized. The gene responsible for suppression, era, encodes an essential GTPase of Escherichia coli. One mutation, rnc-15, is an insertion of an IS1 element within the leader region of the rnc operon and causes a polar defect on the downstream genes of the operon. A previously described polar mutation, rnc-40, was also able to suppress dnaG2903. The other mutation, era-1, causes a single amino acid substitution (P17R) in the G1 region of the GTP-binding domain of Era. Analysis of the GTPase activity of the Era-1 mutant protein showed a four- to five-fold decrease in the ability to convert GTP to GDP. Thus, lowered expression of wild-type Era caused by the polar mutations and reduced GTPase activity caused by the era-1 mutation suppresses dnaG2903 as well as a second dnaG allele, parB. Phenotypic analysis of the era-1 mutant at 25 degrees C showed that 10% of the cells contain four segregated nucleoids, indicative of a delay in cell division. Possible mechanisms of suppression of dnaG and roles for Era are discussed.
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收藏
页码:4575 / 4582
页数:8
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