Studies on the E. coli groNB (nusB) gene which affects bacteriophage λ N gene function

Abstract

Escherichia coli mutants, called groNB, which block the growth of bacteriophage lambda at the level of action of the gene N product, have been isolated as survivors at 42 degrees C of bacteria carrying a) the defective prophage lambda bio11 i lambda cI857 delta H1 or b) the pcR1 plasmid containing the EcoRI immunity fragment of phage lambda cI857. In addition, groNB bacterial mutants have been isolated at 37 degrees C, as large colony formers in the presence of lambda i lambda cI h434, lambda i lambda cI h lambda, and lambda i lambda cI h80 phage. The groNB locus is located at 9 minute of the E. coli genetic map with the order of the neighboring loci being proC tsx groNB purE. Most groNB mutations isolated at 42 degrees C were found to interfere in addition with bacterial growth at low temperatures, since (a) the GroNB phenotypes of lambda growth inhibition and bacterial cold sensitivity cannot be separated by P1 transduction, and (b) some cold resistant revertants simultaneously become Gro+ for lambda growth. Lambda transducing phages carrying the groNB+ bacterial gene have been isolated. GroNB mutant bacteria lysogenized by the transducing phage acquire the Gro+ phenotype and simultaneously the cold resistant phenotype, suggesting that the groNB mutations are recessive to the wild-type gene.

Defective antitermination of rRNA transcription and derepression of rRNA and tRNA synthesis in the nusB5 mutant of Escherichia coli.

“…Previous studies have indicated that the NusA and the NusB proteins are involved in various aspects of the regulation of E. coli transcription termination (29)(30)(31)(32)(33) and, since conditionally lethal mutations have been isolated in nusA (34) and nusB (35), it is clear that these proteins perform essential functions in the growth of E. coli cells. Our present results show that one such function may be antitermination of rRNA operon transcription.…”

Transcription antitermination: the λ paradigm updated

“…Although NusB is not an integral ribosomal protein, it does influence translation, as shown by the observation that nusB mutants have slowed translation rates relative to wild type (Taura et aL, 1992), and is associated with ribosomes following high-salt wash (Das and Wolska, 1984). NusB null mutants have the interesting property of being cold sensitive for growth (Taura et aL, 1992;Georgopoulos et aL, 1980). At elevated temperatures, these nusB null mutants grow, but, as discussed above, exhibit reduced translation rates and a Nus-phenotype (Taura et al, 1992).…”

Identification of the rph (RNase PH) gene of Bacillus subtilis: evidence for suppression of cold-sensitive mutations in Escherichia coli

“…Three E. coli strains with unrelated coldsensitive mutations were employed. CG431 carries the nusBl36(Cs) mutation (20). NusB, like NusA, has been implicated in transcription elongation (for a review, see reference 18).…”

“…Accordingly, these physiological differences could result from differences between the requirements for growth at lower versus higher temperatures. Two examples of gene products that appear to be required only at low temperatures are those of the yeast SACi gene, an apparent component of the cytoskeleton (34), and the E. coli nusB gene, a transcription elongation factor (20). Moreover, in E. coli, cold-sensitive but not thermal-sensitive mutations affecting ribosome assembly could be isolated (22,48).…”