Identification and characterization of a new Escherichia coli gene that is a dosage-dependent suppressor of a dnaK deletion mutation.
We report the isolation and characterization of a previously unidentified Escherichia coli gene that suppresses the temperature-sensitive growth and filamentation of a dnaK deletion mutant strain. Introduction of a multicopy plasmid carrying this wild-type gene into a dnaK deletion mutant strain rescued the temperature-sensitive growth of the dnaK deletion mutant strain at 40.5 degrees C and the filamentation, fully at 37 degrees C and partially at 40.5 degrees C. However, the inability of dnaK mutant cells to support bacteriophage lambda growth was not suppressed. This gene was also able to suppress the temperature-sensitive growth of a grpE280 mutant strain at 41 degrees C. Filamentation of the grpE280 mutant strain was suppressed at 37 degrees C but not at 41 degrees C. The dnaK suppressor gene, designated dksA, maps near the mrcB gene (3.7 min on the E. coli chromosome). DNA sequence analysis and in vivo experiments showed that dksA encodes a 17,500-Mr polypeptide. Gene disruption experiments indicated that dksA is not an essential gene.
Kang
P J
PJ
Department of Physiological Chemistry, University of Wisconsin, Madison53706.
Craig
E A
EA
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D008040:Genetic Linkage; D005838:Genotype; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D012097:Repressor Proteins / Q000235:genetics*; D015183:Restriction Mapping; D013489:Suppression, Genetic; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C063842:dnaK protein, E coli