The <scp><scp>Crc</scp></scp> and <scp><scp>Hfq</scp></scp> proteins of <scp><i>P</i></scp><i>seudomonas putida</i> cooperate in catabolite repression and formation of ribonucleic acid complexes with specific target motifs

Moreno, Renata; Hernández-Arranz, Sofía; Rosa, Ruggero La; Yuste, Luís; Madhushani, Anjana; Shingler, Victoria; Rojo, Fernando

doi:10.1111/1462-2920.12499

Cited by 109 publications

(156 citation statements)

References 57 publications

(101 reference statements)

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“…Our current model of CCR in P. fluorescens SBW25 shows that, in the presence of succinate, CbrAB activates the expression of two noncoding small RNAs (CrcY and CrcZ) which sequestrate the Crc/Hfq protein complex, relieving Crc-and Hfqmediated repression of mRNA transcripts of catabolic enzymes and transporters, including those for the uptake and degradation of xylose (49). Similar mechanisms have been reported in model strains of P. aeruginosa and P. putida (51)(52)(53). While CbrAB is positioned at the top of the CCR regulatory hierarchy, how CbrAB perceives and processes complex nutrient signals remains elusive.…”

Section: Discussionsupporting

confidence: 59%

Role of the Transporter-Like Sensor Kinase CbrA in Histidine Uptake and Signal Transduction

et al. 2015

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CbrA is an atypical sensor kinase found in Pseudomonas. The autokinase domain is connected to a putative transporter of the sodium/solute symporter family (SSSF). CbrA functions together with its cognate response regulator, CbrB, and plays an important role in nutrient acquisition, including regulation of hut genes for the utilization of histidine and its derivative, urocanate. Here we report on the findings of a genetic and biochemical analysis of CbrA with a focus on the function of the putative transporter domain. The work was initiated with mutagenesis of histidine uptake-proficient strains to identify histidine-specific transport genes located outside the hut operon. Genes encoding transporters were not identified, but mutations were repeatedly found in cbrA. This, coupled with the findings of [ 3 H]histidine transport assays and further mutagenesis, implicated CbrA in histidine uptake. In addition, mutations in different regions of the SSSF domain abolished signal transduction. Site-specific mutations were made at four conserved residues: W55 and G172 (SSSF domain), H766 (H box), and N876 (N box). The mutations W55G, G172H, and N876G compromised histidine transport but had minimal effects on signal transduction. The H766G mutation abolished both transport and signal transduction, but the capacity to transport histidine was restored upon complementation with a transport-defective allele of CbrA, most likely due to interdomain interactions. Our combined data implicate the SSSF domain of CbrA in histidine transport and suggest that transport is coupled to signal transduction. IMPORTANCENutrient acquisition in bacteria typically involves membrane-bound sensors that, via cognate response regulators, determine the activity of specific transporters. However, nutrient perception and uptake are often coupled processes. Thus, from a physiological perspective, it would make sense for systems that couple the process of signaling and transport within a single protein and where transport is itself the stimulus that precipitates signal transduction to have evolved. The CbrA regulator in Pseudomonas represents a unique type of sensor kinase whose autokinase domain is connected to a transporter domain. We present genetic and biochemical evidence that suggests that CbrA plays a dual role in histidine uptake and sensing and that transport is dependent on signal transduction.T he ability to recognize and convert external environmental stimuli into appropriate physiological responses is of fundamental importance for all organisms. In bacteria, signal transduction is predominantly mediated by two-component regulatory systems (TCSs) consisting of a sensor kinase (SK) and a cognate response regulator (RR) (1, 2). Both proteins are typically composed of two distinct functional domains (3): a variable N-terminal signal input domain and a conserved C-terminal autokinase domain for the SK and a conserved N-terminal receiver (Rec) domain and a variable C-terminal output domain for the RR. Signal transduction is achieved via ph...

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Section: Discussionsupporting

confidence: 59%

Role of the Transporter-Like Sensor Kinase CbrA in Histidine Uptake and Signal Transduction

et al. 2015

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“…It has been found that the Cbr/ Hfq/Crc system, Cyo terminal oxidase, and the PTSNtr system are involved in such regulation (40,43,44). The Cbr/Hfq/Crc regulatory system involves small RNAs that scavenge the mRNA binding protein complex, Hfq/Crc, resulting in a block of translation of their targeted mRNA (45)(46)(47)(48)(49)(50)(51)(52). The identification of putative Hfq/ Crc binding sites upstream of pueA and pueB genes, the lack of differences in pueA and pueB transcript levels (data not shown), and the effects of carbon source types on Pf-5 Impranil degradation suggest that the expression of PueA and PueB might be regulated at the posttranscriptional level by carbon catabolite repression.…”

Section: Discussionmentioning

confidence: 99%

Carbon Catabolite Repression and Impranil Polyurethane Degradation in Pseudomonas protegens Strain Pf-5

Hung

Zingarelli

Nadeau

et al. 2016

Appl Environ Microbiol

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Polyester polyurethane (PU) coatings are widely used to help protect underlying structural surfaces but are susceptible to biological degradation. PUs are susceptible to degradation by Pseudomonas species, due in part to the degradative activity of secreted hydrolytic enzymes. Microorganisms often respond to environmental cues by secreting enzymes or secondary metabolites to benefit their survival. This study investigated the impact of exposing several Pseudomonas strains to select carbon sources on the degradation of the colloidal polyester polyurethane Impranil DLN (Impranil). The prototypic Pseudomonas protegens strain Pf-5 exhibited Impranil-degrading activities when grown in sodium citrate but not in glucose-containing medium. Glucose also inhibited the induction of Impranil-degrading activity by citrate-fed Pf-5 in a dose-dependent manner. Biochemical and mutational analyses identified two extracellular lipases present in the Pf-5 culture supernatant (PueA and PueB) that were involved in degradation of Impranil. Deletion of the pueA gene reduced Impranil-clearing activities, while pueB deletion exhibited little effect. Removal of both genes was necessary to stop degradation of the polyurethane. Bioinformatic analysis showed that putative Cbr/Hfq/Crc-mediated regulatory elements were present in the intergenic sequences upstream of both pueA and pueB genes. Our results confirmed that both PueA and PueB extracellular enzymes act in concert to degrade Impranil. Furthermore, our data showed that carbon sources in the growth medium directly affected the levels of Impranil-degrading activity but that carbon source effects varied among Pseudomonas strains. This study uncovered an intricate and complicated regulation of P. protegens PU degradation activity controlled by carbon catabolite repression. IMPORTANCEPolyurethane (PU) coatings are commonly used to protect metals from corrosion. Microbiologically induced PU degradation might pose a substantial problem for the integrity of these coatings. Microorganisms from diverse genera, including pseudomonads, possess the ability to degrade PUs via various means. This work identified two extracellular lipases, PueA and PueB, secreted by P. protegens strain Pf-5, to be responsible for the degradation of a colloidal polyester PU, Impranil. This study also revealed that the expression of the degradative activity by strain Pf-5 is controlled by glucose carbon catabolite repression. Furthermore, this study showed that the Impranil-degrading activity of many other Pseudomonas strains could be influenced by different carbon sources. This work shed light on the carbon source regulation of PU degradation activity among pseudomonads and identified the polyurethane lipases in P. protegens.

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“…Hfq is now recognized as an RNA chaperone that promotes the interaction of numerous base-pairing small RNAs (sRNAs) with their mRNA targets and CsrA as a sequence-specific RNA binding protein, both of which globally influence gene expression and virulence (3)(4)(5)(6)(7)(8). Other posttranscriptional regulators also participate in bacterial virulence networks, including RNA helicases, ribonucleases, and the Crc protein of pseudomonads (9)(10)(11)(12)(13)(14)(15).…”

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confidence: 99%

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Vakulskas

Potts

Babitzke

et al. 2015

Microbiol Mol Biol Rev

302

400

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SUMMARY Most bacterial pathogens have the remarkable ability to flourish in the external environment and in specialized host niches. This ability requires their metabolism, physiology, and virulence factors to be responsive to changes in their surroundings. It is no surprise that the underlying genetic circuitry that supports this adaptability is multilayered and exceedingly complex. Studies over the past 2 decades have established that the CsrA/RsmA proteins, global regulators of posttranscriptional gene expression, play important roles in the expression of virulence factors of numerous proteobacterial pathogens. To accomplish these tasks, CsrA binds to the 5′ untranslated and/or early coding regions of mRNAs and alters translation, mRNA turnover, and/or transcript elongation. CsrA activity is regulated by noncoding small RNAs (sRNAs) that contain multiple CsrA binding sites, which permit them to sequester multiple CsrA homodimers away from mRNA targets. Environmental cues sensed by two-component signal transduction systems and other regulatory factors govern the expression of the CsrA-binding sRNAs and, ultimately, the effects of CsrA on secretion systems, surface molecules and biofilm formation, quorum sensing, motility, pigmentation, siderophore production, and phagocytic avoidance. This review presents the workings of the Csr system, the paradigm shift that it generated for understanding posttranscriptional regulation, and its roles in virulence networks of animal and plant pathogens.

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The Crc and Hfq proteins of Pseudomonas putida cooperate in catabolite repression and formation of ribonucleic acid complexes with specific target motifs

Cited by 109 publications

References 57 publications

Role of the Transporter-Like Sensor Kinase CbrA in Histidine Uptake and Signal Transduction

Role of the Transporter-Like Sensor Kinase CbrA in Histidine Uptake and Signal Transduction

Carbon Catabolite Repression and Impranil Polyurethane Degradation in Pseudomonas protegens Strain Pf-5

Regulation of Bacterial Virulence by Csr (Rsm) Systems

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