共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
The genes coding for the RNA-polymerase beta,beta'-subunits and adjacent ribosomal protein genes in Escherichia coli, Salmonella typhimurium, Shigella flexneri, Serratia marcescens, Proteus mirabilis and Pseudomonas putida are compared by the Southern hybridization procedure. In all the species studied close clustering of the genes rplKAJL and rpoBC is demonstrated. Preliminary physical maps for these genes in S. typhimurium, S. flexneri, S. marcescens and P. mirabilis are proposed. Rifampicin is shown to stimulate the beta,beta'-subunit synthesis in all the species studied, suggesting the existence of attenuators localized in front of the rpoBC genes. The similar arrangement of the genes rplKAJLrpoBC in a number of bacterial species is proposed to be due to common mechanisms of their coordinate expression. 相似文献
4.
The endosymbiont theory proposes that chloroplasts have originated from ancestral cyanobacteria through a process of engulfment and subsequent symbiotic adaptation. The molecular data for testing this theory have mainly been the nucleotide sequence of rRNAs and of photosystem component genes. In order to provide additional data in this area, we have isolated genomic clones of Synechocystis DNA containing the ribosomal protein gene cluster rplJL. The nucleotide sequence of this cluster and flanking regions was determined and the derived amino acid sequences were compared to the available homologous sequences from other eubacteria and chloroplasts. In Escherichia coli these two genes are part of a larger cluster, i.e., rplKAJL-rpoBC. In Synechocystis, the genes for the RNA polymerase subunit (rpoBC) are shown to be widely separated from the r-protein genes. The Synechocystis gene arrangement is similar to that in the chloroplast system, where the rpoBC1C2 and rplKAJL clusters are separated and located in two cell compartments, the chloroplast and the nucleus, respectively. 相似文献
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
Song M Kim HJ Kim EY Shin M Lee HC Hong Y Rhee JH Yoon H Ryu S Lim S Choy HE 《The Journal of biological chemistry》2004,279(33):34183-34190
We have examined expression of the genes on Salmonella pathogenicity island 1 (SPI1) during growth under the physiologically well defined standard growth condition of Luria-Bertani medium with aeration. We found that the central regulator hilA and the genes under its control are expressed at the onset of stationary phase. Interestingly, the two-component regulatory genes hilC/hilD, sirA/barA, and ompR, which are known to modulate expression from the hilA promoter (hilAp) under so-called "inducing conditions" (Luria-Bertani medium containing 0.3 m NaCl without aeration), acted under standard conditions at the stationary phase induction level. The induction of hilAp depended not on RpoS, the stationary phase sigma factor, but on the stringent signal molecule ppGpp. In the ppGpp null mutant background, hilAp showed absolutely no activity. The stationary phase induction of hilAp required spoT but not relA. Consistent with this requirement, hilAp was also induced by carbon source deprivation, which is known to transiently elevate ppGpp mediated by spoT function. The observation that amino acid starvation elicited by the addition of serine hydroxamate did not induce hilAp in a RelA(+) SpoT(+) strain suggested that, in addition to ppGpp, some other alteration accompanying entry into the stationary phase might be necessary for induction. It is speculated that during the course of infection Salmonella encounters various stressful environments that are sensed and translated to the intracellular signal, ppGpp, which allows expression of Salmonella virulence genes, including SPI1 genes. 相似文献
18.
19.
20.
Nanamiya H Kasai K Nozawa A Yun CS Narisawa T Murakami K Natori Y Kawamura F Tozawa Y 《Molecular microbiology》2008,67(2):291-304
Bacterial alarmone (p)ppGpp, is a global regulator responsible for the stringent control. Two homologous (p)ppGpp synthetases, RelA and SpoT, have been identified and characterized in Escherichia coli, whereas Gram-positive bacteria such as Bacillus subtilis have been thought to possess only a single RelA-SpoT enzyme. We have now identified two genes, yjbM and ywaC, in B. subtilis that encode a novel type of alarmone synthetase. The predicted products of these genes are relatively small proteins ( approximately 25 kDa) that correspond to the (p)ppGpp synthetase domain of RelA-SpoT family members. A database survey revealed that genes homologous to yjbM and ywaC are conserved in certain bacteria belonging to Firmicutes or Actinobacteria phyla but not in other phyla such as Proteobacteria. We designated the proteins as small alarmone synthetases (SASs) to distinguish them from RelA-SpoT proteins. The (p)ppGpp synthetase function of YjbM and YwaC was confirmed by genetic complementation analysis and by in vitro assay of enzyme activity. Molecular genetic analysis also revealed that ywaC is induced by alkaline shock, resulting in the transient accumulation of ppGpp. The SAS proteins thus likely function in the biosynthesis of alarmone with a mode of action distinct from that of RelA-SpoT homologues. 相似文献