Catabolite repression of the citST two-component system in Bacillus subtilis

Repizo, Guillermo Daniel; Blancato, Víctor Sebastián; Sender, Pablo D.; Lolkema, Juke S.; Magni, Christian

doi:10.1111/j.1574-6968.2006.00318.x

Cited by 10 publications

(8 citation statements)

References 23 publications

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“…A great unexplored area in Streptomyces CCR is the potential role of two-component systems. In other soil living or environmental strains such Pseudomonas , Sinorhizobium and Bacillus , two-component systems are important in CCR control [ 50 – 52 ].…”

Section: Resultsmentioning

confidence: 99%

Transcriptomic analysis of a classical model of carbon catabolite regulation in Streptomyces coelicolor

et al. 2016

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BackgroundIn the genus Streptomyces, one of the most remarkable control mechanisms of physiological processes is carbon catabolite repression (CCR). This mechanism regulates the expression of genes involved in the uptake and utilization of alternative carbon sources. CCR also affects the synthesis of secondary metabolites and morphological differentiation. Even when the outcome effect of CCR in different bacteria is the same, their essential mechanisms can be quite different. In several streptomycetes glucose kinase (Glk) represents the main glucose phosphorylating enzyme and has been regarded as a regulatory protein in CCR. To evaluate the paradigmatic model proposed for CCR in Streptomyces, a high-density microarray approach was applied to Streptomyces coelicolor M145, under repressed and non-repressed conditions. The transcriptomic study was extended to assess the ScGlk role in this model by comparing the transcriptomic profile of S. coelicolor M145 with that of a ∆glk mutant derived from the wild-type strain, complemented with a heterologous glk gene from Zymomonas mobilis (Zmglk), insensitive to CCR but able to grow in glucose (ScoZm strain).ResultsMicroarray experiments revealed that glucose influenced the expression of 651 genes. Interestingly, even when the ScGlk protein does not have DNA binding domains and the glycolytic flux was restored by a heterologous glucokinase, the ScGlk replacement modified the expression of 134 genes. From these, 91 were also affected by glucose while 43 appeared to be under the control of ScGlk. This work identified the expression of S. coelicolor genes involved in primary metabolism that were influenced by glucose and/or ScGlk. Aside from describing the metabolic pathways influenced by glucose and/or ScGlk, several unexplored transcriptional regulators involved in the CCR mechanism were disclosed.ConclusionsThe transcriptome of a classical model of CCR was studied in S. coelicolor to differentiate between the effects due to glucose or ScGlk in this regulatory mechanism. Glucose elicited important metabolic and transcriptional changes in this microorganism. While its entry and flow through glycolysis and pentose phosphate pathway were stimulated, the gluconeogenesis was inhibited. Glucose also triggered the CCR by repressing transporter systems and the transcription of enzymes required for secondary carbon sources utilization. Our results confirm and update the agar model of the CCR in Streptomyces and its dependence on the ScGlk per se. Surprisingly, the expected regulatory function of ScGlk was not found to be as global as thought before (only 43 out of 779 genes were affected), although may be accompanied or coordinated by other transcriptional regulators. Aside from describing the metabolic pathways influenced by glucose and/or ScGlk, several unexplored transcriptional regulators involved in the CCR mechanism were disclosed. These findings offer new opportunities to study and understand the CCR in S. coelicolor by increasing the number of known glucose and ScGlk -regulate...

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Section: Resultsmentioning

confidence: 99%

Transcriptomic analysis of a classical model of carbon catabolite regulation in Streptomyces coelicolor

et al. 2016

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“…In Bacillus subtilis , citrate uptake interferes directly with the regulation of the Krebs cycle enzymes, which explains why expression of the transporter is tightly controlled [39]. However, citrate transport by enterococcal cells will not cause an imbalance of metabolites of the TCA because E. faecalis lacks most of the enzymes of the Krebs cycle.…”

Section: Discussionmentioning

confidence: 99%

CcpA represses the expression of the divergent cit operons of Enterococcus faecalis through multiple cresites

et al. 2011

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BackgroundIn Enterococcus faecalis the genes encoding the enzymes involved in citrate metabolism are organized in two divergent operons, citHO and oadHDB-citCDEFX-oadA-citMG (citCL locus). Expression of both operons is specifically activated by adding citrate to the medium. This activation is mediated by binding of the GntR-like transcriptional regulator (CitO) to the cis-acting sequences located in the cit intergenic region. Early studies indicated that citrate and glucose could not be co-metabolized suggesting some form of catabolite repression, however the molecular mechanism remained unknown.ResultsIn this study, we observed that the citHO promoter is repressed in the presence of sugars transported by the Phosphoenolpyruvate:carbohydrate Phosphotranserase System (PTS sugars). This result strongly suggested that Carbon Catabolic Repression (CCR) impedes the expression of the activator CitO and the subsequent induction of the cit pathway. In fact, we demonstrate that CCR is acting on both promoters. It is partially relieved in a ccpA-deficient E. faecalis strain indicating that a CcpA-independent mechanism is also involved in regulation of the two operons. Furthermore, sequence analysis of the citH/oadH intergenic region revealed the presence of three putative catabolite responsive elements (cre). We found that they are all active and able to bind the CcpA/P-Ser-HPr complex, which downregulates the expression of the cit operons. Systematic mutation of the CcpA/P-Ser-HPr binding sites revealed that cre1 and cre2 contribute to citHO repression, while cre3 is involved in CCR of citCLConclusionIn conclusion, our study establishes that expression of the cit operons in E. faecalis is controlled by CCR via CcpA-dependent and -independent mechanisms.

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“…Expression is repressed by carbon catabolite repression [15] and by arginine metabolism [16], and induced by a two‐component sensory system [15,17]. Moreover, the expression of the latter is itself under control of carbon catabolite repression [18]. B. subtilis and E. faecalis will be at a similar risk in citrate‐containing medium in the presence of Cd 2+ or Pb 2+ when Ef CitH and Bs CitH are expressed.…”

Section: Discussionmentioning

confidence: 99%

Functional characterization and Me²⁺ ion specificity of a Ca²⁺–citrate transporter from Enterococcus faecalis

2006

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Secondary transporters of the bacterial CitMHS family transport citrate in complex with a metal ion. Different members of the family are specific for the metal ion in the complex and have been shown to transport Mg2+–citrate, Ca2+–citrate or Fe3+–citrate. The Fe3+–citrate transporter of Streptococcus mutans clusters on the phylogenetic tree on a separate branch with a group of transporters found in the phylum Firmicutes which are believed to be involved in anaerobic citrate degradation. We have cloned and characterized the transporter from Enterococcus faecalis EfCitH in this cluster. The gene was functionally expressed in Escherichia coli and studied using right‐side‐out membrane vesicles. The transporter catalyzes proton‐motive‐force‐driven uptake of the Ca2+–citrate complex with an affinity constant of 3.5 µm. Homologous exchange is catalyzed with a higher efficiency than efflux down a concentration gradient. Analysis of the metal ion specificity of EfCitH activity in right‐side‐out membrane vesicles revealed a specificity that was highly similar to that of the Bacillus subtilis Ca2+–citrate transporter in the same family. In spite of the high sequence identity with the S. mutans Fe3+–citrate transporter, no transport activity with Fe3+ (or Fe2+) could be detected. The transporter of E. faecalis catalyzes translocation of citrate in complex with Ca2+, Sr2+, Mn2+, Cd2+ and Pb2+ and not with Mg2+, Zn2+, Ni2+ and Co2+. The specificity appears to correlate with the size of the metal ion in the complex.

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Catabolite repression of the citST two-component system in Bacillus subtilis

Cited by 10 publications

References 23 publications

Transcriptomic analysis of a classical model of carbon catabolite regulation in Streptomyces coelicolor

Transcriptomic analysis of a classical model of carbon catabolite regulation in Streptomyces coelicolor

CcpA represses the expression of the divergent cit operons of Enterococcus faecalis through multiple cresites

Functional characterization and Me²⁺ ion specificity of a Ca²⁺–citrate transporter from Enterococcus faecalis

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Catabolite repression of the citST two-component system in Bacillus subtilis

Cited by 10 publications

References 23 publications

Transcriptomic analysis of a classical model of carbon catabolite regulation in Streptomyces coelicolor

Transcriptomic analysis of a classical model of carbon catabolite regulation in Streptomyces coelicolor

CcpA represses the expression of the divergent cit operons of Enterococcus faecalis through multiple cresites

Functional characterization and Me2+ ion specificity of a Ca2+–citrate transporter from Enterococcus faecalis

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Functional characterization and Me²⁺ ion specificity of a Ca²⁺–citrate transporter from Enterococcus faecalis