DnaK-dependent ribosome biogenesis in Escherichia coli: competition for dominance between the alleles dnaK756 and dnaK super(+)

• Published in: Molecular & general genetics Vol. 260; no. 2-3; pp. 199 - 206
• Main Authors: Sbai, M, Alix, J-H
• Format: Journal Article
• Language: English
• Published: 28.11.1998
• Subjects: Escherichia coli
• ISSN: 0026-8925

The Escherichia coli chaperone DnaK is vital for many cellular functions, including ribosome biogenesis at high temperature. Thus, the dnaK756-ts ( super(R)) mutant, at the non-permissive temperature, is inhibited at a late stage of ribosome assembly, yielding 21S, 32S and 45S precursor particles. This defect, unlike the resistance and thermosensitivity phenotypes, is not complemented by lysogenisation with a transducing phage dnaK super(+) bearing the wild-type dnaK gene. However this dominant phenotype becomes recessive when dnaK super(+) is expressed from a medium-copy-number plasmid. On the other hand, an excess of DnaK causes an unexpected dominant-lethal effect of the dnaK756 allele near non-permissive temperatures. This interplay between the dnaK super(+) and dnaK756 alleles supports the idea of that DnaK oligomers form in the cell.