Autogenous regulation of transcription termination factor Rho

Barik, Sailen; Bhattacharya, Pramatha R.; Das, Asis

doi:10.1016/0022-2836(85)90236-0

Cited by 31 publications

(18 citation statements)

References 42 publications

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“…The precise site of occurrence of the latter remains to be determined. This scheme is reminiscent of the mechanism by which Rho factor autoregulates its own synthesis by transcription attenuation (4,25,33). Our results would also suggest, by analogy, that Rho-dependent attenuation occurs for native E. coli P1-associated expression (that is, in the presence of the long downstream sequence), at least during growth at 10°C, but once again the cis site of action is not known.…”

Section: Discussionmentioning

confidence: 58%

In Vivo Expression from the RpoS-Dependent P1 Promoter of the Osmotically Regulated proU Operon in Escherichia coli and Salmonella enterica Serovar Typhimurium: Activation by rho and hns Mutations and by Cold Stress

Rajkumari

Gowrishankar

2001

J Bacteriol

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Unlike the 70 -controlled P2 promoter for the osmotically regulated proU operon of Escherichia coli and Salmonella enterica serovar Typhimurium, the s -controlled P1 promoter situated further upstream appears not to contribute to expression of the proU structural genes under ordinary growth conditions. For S. enterica proU P1, there is evidence that promoter crypticity is the result of a transcription attenuation phenomenon which is relieved by the deletion of a 22-base C-rich segment in the transcript. In this study, we have sought to identify growth conditions and trans-acting mutations which activate in vivo expression from proU P1. The cryptic S. enterica proU P1 promoter was activated, individually and additively, in a rho mutant (which is defective in the transcription termination factor Rho) as well as by growth at 10°C. The E. coli proU P1 promoter was also cryptic in constructs that carried 1.2 kb of downstream proU sequence, and in these cases activation of in vivo expression was achieved either by a rho mutation during growth at 10°C or by an hns null mutation (affecting the nucleoid protein H-NS) at 30°C. The rho mutation had no effect at either 10 or 30°C on in vivo expression from two other s -controlled promoters tested, those for osmY and csiD. In cells lacking the RNA-binding regulator protein Hfq, induction of E. coli proU P1 at 10°C and by hns mutation at 30°C was still observed, although the hfq mutation was associated with a reduction in the absolute levels of P1 expression. Our results suggest that expression from proU P1 is modulated both by nucleoid structure and by Rhomediated transcription attenuation and that this promoter may be physiologically important for proU operon expression during low-temperature growth.The ProU transporter in Escherichia coli and Salmonella enterica serovar Typhimurium is a binding-protein-dependent transport system that mediates the cytoplasmic accumulation of compatible solutes such as glycine betaine, L-proline, and related compounds during growth of cells in media of elevated osmolarity (9, 10). The subunit polypeptides of the transporter are encoded by three genes, proV, proW, and proX, which together constitute (in that order) the proU operon (16).Transcription of proU in both E. coli and S. enterica is activated several-hundredfold in cultures grown in high-osmolarity media, but the mechanism of osmotic induction of the operon is not fully understood (reviewed in references 10, 19, and 29). Two cis regulatory elements that have been identified (see Fig. 1) include a 70 -driven promoter whose transcription start site is situated 60 bases upstream of proV (16, 24, 28, 54) and a negative regulatory element (NRE) approximately 500 bp long, which is situated downstream of the promoter (overlapping the proV coding region) and whose deletion results in partial derepression of proU at low osmolarity (11,24,37,38). Mutations in hns, the gene encoding an abundant nucleoid protein, H-NS, also result in partial derepression of proU expression (for a review of H-NS...

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Section: Discussionmentioning

confidence: 58%

In Vivo Expression from the RpoS-Dependent P1 Promoter of the Osmotically Regulated proU Operon in Escherichia coli and Salmonella enterica Serovar Typhimurium: Activation by rho and hns Mutations and by Cold Stress

Rajkumari

Gowrishankar

2001

J Bacteriol

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“…10A). This Rho-binding site is responsible for the feedback regulation present in this operon (36). We probed the NusA-mediated inhibition of the Rho-dependent transcription termination in the rho operon.…”

Section: Nusa Binding To Nut Site(s) Delays the Loading Of Rho At Thementioning

confidence: 99%

“…The Rho protein level increases when Rho-dependent termination is compromised (36). Therefore, it is expected that NusA-mediated inhibition of Rho-dependent termination in this operon should also increase the level of Rho, and this increase would be much higher in the presence of NusA mutants, G181D and R258C.…”

Section: Nusa Binding To Nut Site(s) Delays the Loading Of Rho At Thementioning

confidence: 99%

Transcription Elongation Factor NusA Is a General Antagonist of Rho-dependent Termination in Escherichia coli

Qayyum

Dey

Sen

2016

Journal of Biological Chemistry

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NusA is an essential protein that binds to RNA polymerase and also to the nascent RNA and influences transcription by inducing pausing and facilitating the process of transcription termination/antitermination. Its participation in Rho-dependent transcription termination has been perceived, but the molecular nature of this involvement is not known. We hypothesized that, because both Rho and NusA are RNA-binding proteins and have the potential to target the same RNA, the latter is likely to influence the global pattern of the Rho-dependent termination. Analyses of the nascent RNA binding properties and consequent effects on the Rho-dependent termination functions of specific NusA-RNA binding domain mutants revealed an existence of Rho-NusA direct competition for the overlapping nut (NusA-binding site) and rut (Rho-binding site) sites on the RNA. This leads to delayed entry of Rho at the rut site that inhibits the latter's RNA release process. High density tiling microarray profiles of these NusA mutants revealed that a significant number of genes, together with transcripts from intergenic regions, are up-regulated. Interestingly, the majority of these genes were also up-regulated when the Rho function was compromised. These results provide strong evidence for the existence of NusA-binding sites in different operons that are also the targets of Rho-dependent terminations. Our data strongly argue in favor of a direct competition between NusA and Rho for the access of specific sites on the nascent transcripts in different parts of the genome. We propose that this competition enables NusA to function as a global antagonist of the Rho function, which is unlike its role as a facilitator of hairpin-dependent termination.The bacterial transcription terminator, Rho, functions as a hexameric RNA-dependent ATPase that is capable of translocating along the RNA. It dislodges the elongating RNA polymerase (RNAP) 4 once it is loaded onto the nascent RNA (1, 2). Its termination function is facilitated upon interaction with the transcription elongation factor, NusG (3-5). Recent genomics studies have revealed that Rho-dependent termination occurs at more than one-third of the operons of a dividing Escherichia coli (6, 7). This mode of transcription termination is involved in many physiological processes, like control of translation (2), riboswitch formation (8), inhibition of unwanted antisense transcription, etc. (7). Rho is capable of loading onto unstructured stretches of RNA (the rut ([R]ho [ut]ilization) sites), and once it is bound to the RNA, it translocates in a processive manner along the 5Јto 3Ј direction, which may induce unwanted termination of transcription. Interestingly, in vivo negative regulation by cellular factors or any control switch of the Rho function has not been documented. In principle, any RNA-binding protein that has overlapping binding sites with the rut sites on the nascent RNA could influence the Rho activity by a direct competition for occupancy of the same sites.NusA, a ubiquitous transcription elo...

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“…When the cell den units, chloramphenicol (50 ,ug/ml) wa to stop the cell growth. The cells wer ugation, suspended in saline, and a sidase activity as described by Miller saline suspension was used for deter 4 Rho LacZ the method of Lowry et al (37 the trxA and rho promoters were purified by electrophoresis tation test, the upstream on polyacrylamide gel and used for sequence determination half of the rho structural by enzymatic methods (17,18,36) 40 Klett is added to the culture e harvested by centrifassayed for 3-galactor- (41). A sample of the mination of protein by…”

mentioning

confidence: 99%

Autogenous regulation of the gene for transcription termination factor rho in Escherichia coli: localization and function of its attenuators

Matsumoto¹,

Shigesada²,

Hirano³

et al. 1986

J Bacteriol

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We present evidence that the expression of rho is regulated by rho-dependent attenuation of transcription. Gene fusion analysis with nested series of deletions of rho indicated that the transcription of rho is attenuated in a rho-dependent manner in the leader region and that neither a read-through transcription from the upstream gene, trxA, nor a modulation of transcription initiation of the rho promoter is involved in the self-control of rho. Si mapping and Northern hybridization analyses localized at least six transcription attenuation or termination sites in the region ranging from the 3' end of the trxA structural gene to the middle of the rho structural gene. Among them, the most upstream site overlapping the rho promoter sequence was assigned to the terminator for the trxA gene, and the second and third sites, mapping about 80 and 50 nucleotides upstream from the start codon of rho, were suggested to function as the major attenuation sites for regulation of the rho expression. Further, the start points of the trxA and rho RNAs were determined in an in vitro transcription system to be located 111 nucleotides (U) and 255 nucleotides (G) Kushner, Gene 32:399408, 1984).The termination of transcription plays profound roles in the regulation of gene expression in procaryotes. Termination of RNA synthesis generally occurs at the ends of operons so as to ensure independent expression of neighboring genes. In addition, it can also occur within operons to allow differential expression of genes within an operon. In Escherichia coli, several protein factors which participate in transcription termination or antitermination have been identified: Rho, NusA, NusB, and NusE (14,21,22,25,26,30,47,56).Rho protein causes termination of transcription catalyzed by E. coli RNA polymerase at certain specific sites on DNA template (47). These sites are called Rho-dependent terminators, as opposed to Rho-independent terminators which are recognized by RNA polymerase without the aid of Rho. Several Rho-dependent terminators have been found at different positions in various operons. For example, trp-t' (57) and the tyrT terminator (33) are located at the ends of their operons, while tLl, tRl, and tR2 are within the leftward and rightward operons of bacteriophage X, respectively (47). It has also been shown that mutational polarity involves Rho-dependent terminators residitng within a structural gene.Such terminators are normally nonfunctional, but are activated when preceding translation is arrested at a nonsense codon introduced by mutation (1, 13). A number of rho mutants of E. coli have been isolated that are defective in Rho-dependent transcription termination (12,28,29,31,46). Some of them are conditional-lethal, suggesting that Rho is essential for cell growth. (27, 45). Conversely, decreased Rho levels have been observed with a new class of rho mutants which is hyperactive in termination (53). These observations suggest that the expression of rho is autogenously regulated. In view of the role of Rho as a transcription term...

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Autogenous regulation of transcription termination factor Rho

Cited by 31 publications

References 42 publications

In Vivo Expression from the RpoS-Dependent P1 Promoter of the Osmotically Regulated proU Operon in Escherichia coli and Salmonella enterica Serovar Typhimurium: Activation by rho and hns Mutations and by Cold Stress

In Vivo Expression from the RpoS-Dependent P1 Promoter of the Osmotically Regulated proU Operon in Escherichia coli and Salmonella enterica Serovar Typhimurium: Activation by rho and hns Mutations and by Cold Stress

Transcription Elongation Factor NusA Is a General Antagonist of Rho-dependent Termination in Escherichia coli

Autogenous regulation of the gene for transcription termination factor rho in Escherichia coli: localization and function of its attenuators

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