H-NS over-expression induces an artificial stationary phase by silencing global transcription.
Bacteria organize their chromosomes in a complex interwound supercoiled structure called the nucleoid through the action of topoisomerases and a set of small (10-20 kDa) proteins. The two most abundant nucleoid-associated proteins are HU and H-NS. H-NS increases in abundance during stationary phase. Over-expression of HU is well tolerated and compatible with transcription and cell growth. Increasing the concentration of H-NS leads to a rapid silencing of global transcription and produces a growth-arrested state reminiscent of stationary phase. H-NS over-expression also induces a substantial loss of supercoiling in plasmid DNA during the time that transcription is arrested. Comparing the effects of over-expression of these two proteins gives some insight into the differential roles of these proteins in the activity of the chromosome. These observations are interpreted in a model of nucleoid organization.
McGovern
V
V
Department of Biochemistry, University of Alabama at Birmingham 35294, USA.
Higgins
N P
NP
Chiz
R S
RS
Jaworski
A
A
D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis*; D001426:Bacterial Proteins; D001483:Base Sequence; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D007399:Interphase / Q000235:genetics*; D008969:Molecular Sequence Data; D010641:Phenotype; D014158:Transcription, Genetic
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria