Identification of RamA, a Novel LuxR-Type Transcriptional Regulator of Genes Involved in Acetate Metabolism of
            <i>Corynebacterium glutamicum</i>

Cramer, Annette; Gerstmeir, Robert; Schaffer, Steffen; Bott, Michael; Eikmanns, Bernhard J.

doi:10.1128/jb.188.7.2554-2567.2006

Cited by 105 publications

(156 citation statements)

References 59 publications

(82 reference statements)

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“…Moreover, expression of the representative RamA regulon members sugR and aceA in strain KT27 was also comparable to that in the wild type (data not shown). As RamA is essential for expression of aceA encoding isocitrate lyase in the glyoxylate shunt, the ramA mutant shows a growth defect on acetate (38). In contrast, the growth of strain KT27 on acetate was comparable to that of the wild type (data not shown).…”

Section: Resultsmentioning

confidence: 72%

“…The ␤-galactosidase activity driven by the native and mutated promoters during growth in nutrient-rich medium (A medium) containing either 1% glucose or 1% acetate was determined. We used the medium because the ramA deletion mutant strains described in the following section are incapable of growing on acetate as the sole carbon source, as has been reported (38). The activities were largely unchanged during growth, although they slightly increased in some of these strains used in the later growth phase.…”

Section: Resultsmentioning

confidence: 99%

“…On the basis of the presumed physiological function of each type of FFL, the coherent FFLs formed with GlxR-RamA and SugR-RamA are predicted to play a role in maintaining gapA expression levels in response to fluctuations in cAMP and sugar phosphate levels, whereas the incoherent FFL composed of RamA-SugR may be involved in a rapid response to physiological and/or environmental changes, which are sensed by RamA. Moreover, the FFLs formed by GlxR and RamA are possibly involved in regulation of other central carbon metabolism genes, i.e., ptsF, gltA, acn, sdhCAB, aceA, and aceB, encoding the fructose uptake phosphotransferase system, citrate synthase, aconitase, succinate dehydrogenase, isocitrate lyase, and malate synthase, respectively (35,38,45,54,(62)(63)(64)(65). Further insights into the biological roles of these complex regulatory connections will be provided by elucidation of the environmental signals to which RamA and RamB respond and how the intracellular cAMP levels are controlled.…”

Section: Discussionmentioning

confidence: 99%

“…As sugar phosphates, e.g., fructose-1-phosphate and fructose-1,6-bisphosphate, act as negative effectors of SugR, the SugR regulon is derepressed in the presence of sugar. GlxR, a cAMP-responsive regulator, and RamA, a LuxR-type regulator, were first identified as the transcriptional repressor and activator, respectively, of the aceB gene, encoding malate synthase of the glyoxylate cycle (14,38). Both regulators not only activate gapA expression (15,31) but are also involved in expression of a number of genes for various physiological functions, including carbon and nitrogen metabolism, respiration, SOS and stress responses, and cell division (15,(39)(40)(41).…”

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confidence: 99%

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Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

et al. 2013

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The central carbon metabolism genes in Corynebacterium glutamicum are under the control of a transcriptional regulatory network composed of several global regulators. It is known that the promoter region of ramA, encoding one of these regulators, interacts with its gene product, RamA, as well as with the two other regulators, GlxR and SugR, in vitro and/or in vivo. Although RamA has been confirmed to repress its own expression, the roles of GlxR and SugR in ramA expression have remained unclear. In this study, we examined the effects of GlxR binding site inactivation on expression of the ramA promoter-lacZ fusion in the genetic background of single and double deletion mutants of sugR and ramA. In the wild-type background, the ramA promoter activity was reduced to undetectable levels by the introduction of mutations into the GlxR binding site but increased by sugR deletion, indicating that GlxR and SugR function as the transcriptional activator and repressor, respectively. The marked repression of ramA promoter activity by the GlxR binding site mutations was largely compensated for by deletions of sugR and/or ramA. Furthermore, ramA promoter activity in the ramA-sugR double mutant was comparable to that in the ramA mutant but was significantly higher than that in the sugR mutant. Taken together, it is likely that the level of ramA expression is dynamically balanced by GlxR-dependent activation and repression by RamA along with SugR in response to perturbation of extracellular and/or intracellular conditions. These findings add multiple regulatory loops to the transcriptional regulatory network model in C. glutamicum.

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Section: Resultsmentioning

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

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“…of cDNA ends] method, generation of polyclonal antibodies, and Western blotting) were described previously (3,4,6).…”

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confidence: 99%

RamB, the Transcriptional Regulator of Acetate Metabolism in Corynebacterium glutamicum , Is Subject to Regulation by RamA and RamB

et al. 2007

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In Corynebacterium glutamicum, the transcriptional regulator RamB negatively controls the expression of genes involved in acetate metabolism. Here we show that RamB represses its own expression by direct interaction with a 13-bp motif in the ramB promoter region. Additionally, ramB expression is subject to carbon source-dependent positive control by RamA.Corynebacterium glutamicum is an aerobic gram-positive soil bacterium well known for its use in large-scale biotechnological production of L-glutamate and lysine (10-14). We are interested in acetate metabolism and its regulation in this organism (7), and we recently identified and characterized two regulatory proteins, designated regulator of acetate metabolism A and B (RamA and RamB, respectively) from C. glutamicum ATCC 13032 (4, 6). RamA binds to single or tandem stretches of A/C/TG 4-6 T/C or AC 4-5 A/G/T and thereby acts as an activator of the pta, ack, aceA, and aceB genes, encoding phosphotransacetylase, acetate kinase, isocitrate lyase, and malate synthase, all involved in acetate metabolism of C. glutamicum. RamA was also shown to activate transcription of the surface layer protein gene (cspB) in C. glutamicum ATCC 14067 (9). Furthermore, RamA was shown to bind to the promoter region of its own gene and to act as a repressor there (3). The RamB protein specifically binds to a highly conserved 13-bp motif (AA/GAACTTTGCAAA) and represents a repressor of the pta, ack, aceA, and aceB genes when C. glutamicum is grown on glucose as a carbon and energy source (6). Inspection of the ramB promoter region revealed the presence of putative RamA and RamB binding sites, and this observation prompted us to study expression of ramB in cells growing in media containing glucose and/or acetate and to test for a regulatory function of RamA and RamB in ramB expression.The bacterial strains and the plasmids, their relevant characteristics and sources, and the oligonucleotides used in this study are given in Table 1. The media used and the methods not outlined explicitly (DNA preparation, promoter binding assays with hexahistidyl-tagged RamA and RamB fusion proteins, enzyme assays, RNA preparation and identification of the transcriptional start site by the RACE [rapid amplification of cDNA ends] method, generation of polyclonal antibodies, and Western blotting) were described previously (3, 4, 6).Western blot experiments with RamB-specific antibodies and crude extracts from C. glutamicum wild-type (WT) cells grown in minimal medium containing glucose, glucose plus acetate, and acetate showed that RamB is present in cells grown on either carbon source (Fig. 1). In agreement with the results of DNA affinity chromatography experiments (4), the largest amounts of RamB were observed in the cells grown on glucose alone.To test for ramB promoter activities in C. glutamicum cells grown in minimal media with glucose and/or acetate, we constructed reporter gene fusions by cloning a 593-bp ramB promoter fragment (covering the region 521 bp upstream to 72 bp downstream of the ramB sta...

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Synthetic Biology for Corynebacterium glutamicum : An Industrial Host for White Biotechnology

Woo

2018

Emerging Areas in Bioengineering

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Identification of RamA, a Novel LuxR-Type Transcriptional Regulator of Genes Involved in Acetate Metabolism of Corynebacterium glutamicum

Cited by 105 publications

References 59 publications

Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

RamB, the Transcriptional Regulator of Acetate Metabolism in Corynebacterium glutamicum , Is Subject to Regulation by RamA and RamB

Synthetic Biology for Corynebacterium glutamicum : An Industrial Host for White Biotechnology

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