当前位置： SCI文献检索 > JOURNAL OF BACTERIOLOGY期刊下所有文献 > Characterization of mutations in the metY-nusA-infB operon that suppress the slow growth of a DeltarimM mutant.

Characterization of mutations in the metY-nusA-infB operon that suppress the slow growth of a DeltarimM mutant.

Abstract：

:The RimM protein in Escherichia coli is associated with free 30S ribosomal subunits but not with 70S ribosomes. A DeltarimM mutant shows a sevenfold-reduced growth rate and a reduced translational efficiency, probably as a result of aberrant assembly of the ribosomal 30S subunits. The slow growth and translational deficiency can be partially suppressed by increased synthesis of the ribosome binding factor RbfA. Here, we have identified 14 chromosomal suppressor mutations that increase the growth rate of a DeltarimM mutant by increasing the expression of rbfA. Nine of these mutations were in the nusA gene, which is located upstream from rbfA in the metY-nusA-infB operon; three mutations deleted the transcriptional terminator between infB and rbfA; one was an insertion of IS2 in infB, creating a new promoter for rbfA; and one was a duplication, placing a second copy of rbfA downstream from a promoter for the yhbM gene. Two of the nusA mutations were identical, while another mutation (nusA98) was identical to a previously isolated mutation, nusA11, shown to decrease termination of transcription. The different nusA mutations were found to increase the expression of rbfA by increasing the read-through of two internal transcriptional terminators located just downstream from the metY gene and that of the internal terminator preceding rbfA. Induced expression of the nusA(+) gene from a plasmid in a nusA(+) strain decreased the read-through of the two terminators just downstream from metY, demonstrating that one target for a previously proposed NusA-mediated feedback regulation of the metY-nusA-infB operon expression is these terminators. All of the nusA mutations produced temperature-sensitive phenotypes of rimM(+) strains. The nusA gene has previously been shown to be essential at 42 degrees C and below 32 degrees C. Here, we show that nusA is also essential at 37 degrees C.

journal_name

J Bacteriol

journal_title

Journal of bacteriology

authors

Bylund GO,Lövgren JM,Wikström PM

doi

10.1128/JB.183.20.6095-6106.2001

keywords:

subject

Has Abstract

pub_date

2001-10-01 00:00:00

pages

6095-106

issue

eissn

0021-9193

issn

1098-5530

journal_volume

183

pub_type

杂志文章

在线工具

Characterization of mutations in the metY-nusA-infB operon that suppress the slow growth of a DeltarimM mutant.