PMID:9226268
| Citation |
Britton, RA, Powell, BS, Court, DL and Lupski, JR (1997) Characterization of mutations affecting the Escherichia coli essential GTPase era that suppress two temperature-sensitive dnaG alleles. J. Bacteriol. 179:4575-82 |
|---|---|
| Abstract |
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. |
| Links | |
| Keywords |
Alleles; Amino Acid Sequence; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; DNA Primase; Escherichia coli/genetics; Escherichia coli/growth & development; Escherichia coli/metabolism; Escherichia coli Proteins; GTP Phosphohydrolases/genetics; GTP Phosphohydrolases/metabolism; GTP-Binding Proteins/genetics; GTP-Binding Proteins/metabolism; Genes, Bacterial; Genes, Suppressor; Guanosine Triphosphate/metabolism; Molecular Sequence Data; Operon; Phenotype; RNA Nucleotidyltransferases/genetics; RNA-Binding Proteins; Suppression, Genetic; Temperature |
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