Core regulon of the global anaerobic regulator Anr targets central metabolism functions in Pseudomonas species

Tribelli, Paula María; Luján, Adela M.; Pardo, Agustín; Ibarra, José G.; Porto, Darío Fernández Do; Smania, Andrea M.; López, Nancy I.

doi:10.1038/s41598-019-45541-0

Cited by 26 publications

(22 citation statements)

References 67 publications

(103 reference statements)

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“…Anr and its homologs have been well-characterized as oxygen-sensitive transcription factors (21)(22)(23). The P. aeruginosa Anr regulon includes genes encoding enzymes involved in microoxic and anoxic respiration, fermentation, microoxic ethanol oxidation, CupA fimbriae synthesis, and a number of hypothetical proteins including a putative hemerythrin PA14_42860 (PA1673) (7,(24)(25)(26).…”

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confidence: 99%

Pseudomonas aeruginosa lasR mutant fitness in microoxia is supported by an Anr-regulated oxygen-binding hemerythrin

Clay

Hammond

Zhong

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Pseudomonas aeruginosa strains with loss-of-function mutations in the transcription factor LasR are frequently encountered in the clinic and the environment. Among the characteristics common to LasR-defective (LasR−) strains is increased activity of the transcription factor Anr, relative to their LasR+ counterparts, in low-oxygen conditions. One of the Anr-regulated genes found to be highly induced in LasR− strains was PA14_42860 (PA1673), which we named mhr for microoxic hemerythrin. Purified P. aeruginosa Mhr protein contained the predicted di-iron center and bound molecular oxygen with an apparent Kd of ∼1 µM. Both Anr and Mhr were necessary for fitness in lasR+ and lasR mutant strains in colony biofilms grown in microoxic conditions, and the effects were more striking in the lasR mutant. Among genes in the Anr regulon, mhr was most closely coregulated with the Anr-controlled high-affinity cytochrome c oxidase genes. In the absence of high-affinity cytochrome c oxidases, deletion of mhr no longer caused a fitness disadvantage, suggesting that Mhr works in concert with microoxic respiration. We demonstrate that Anr and Mhr contribute to LasR− strain fitness even in biofilms grown in normoxic conditions. Furthermore, metabolomics data indicate that, in a lasR mutant, expression of Anr-regulated mhr leads to differences in metabolism in cells grown on lysogeny broth or artificial sputum medium. We propose that increased Anr activity leads to higher levels of the oxygen-binding protein Mhr, which confers an advantage to lasR mutants in microoxic conditions.

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confidence: 99%

Pseudomonas aeruginosa lasR mutant fitness in microoxia is supported by an Anr-regulated oxygen-binding hemerythrin

Clay

Hammond

Zhong

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…Recently, it has become clear that the ANR regulon controls many more functions than was previously thought. In particular, it regulates many genes related to stress response and adaptability, as reported by Tribelli et al [ 31 ]. The role of ANR in PHAs synthesis was also elucidated by Mohanan et al (2019) in P. chlororaphis PA23 [ 32 ].…”

Section: Discussionmentioning

confidence: 86%

Transcriptome Changes in Pseudomonas putida KT2440 during Medium-Chain-Length Polyhydroxyalkanoate Synthesis Induced by Nitrogen Limitation

Dabrowska

Możejko-Ciesielska

Pokój

et al. 2020

IJMS

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Pseudomonas putida’s versatility and metabolic flexibility make it an ideal biotechnological platform for producing valuable chemicals, such as medium-chain-length polyhydroxyalkanoates (mcl-PHAs), which are considered the next generation bioplastics. This bacterium responds to environmental stimuli by rearranging its metabolism to improve its fitness and increase its chances of survival in harsh environments. Mcl-PHAs play an important role in central metabolism, serving as a reservoir of carbon and energy. Due to the complexity of mcl-PHAs’ metabolism, the manner in which P. putida changes its transcriptome to favor mcl-PHA synthesis in response to environmental stimuli remains unclear. Therefore, our objective was to investigate how the P. putida KT2440 wild type and mutants adjust their transcriptomes to synthesize mcl-PHAs in response to nitrogen limitation when supplied with sodium gluconate as an external carbon source. We found that, under nitrogen limitation, mcl-PHA accumulation is significantly lower in the mutant deficient in the stringent response than in the wild type or the rpoN mutant. Transcriptome analysis revealed that, under N-limiting conditions, 24 genes were downregulated and 21 were upregulated that were common to all three strains. Additionally, potential regulators of these genes were identified: the global anaerobic regulator (Anr, consisting of FnrA, Fnrb, and FnrC), NorR, NasT, the sigma54-dependent transcriptional regulator, and the dual component NtrB/NtrC regulator all appear to play important roles in transcriptome rearrangement under N-limiting conditions. The role of these regulators in mcl-PHA synthesis is discussed.

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“…CapB, a cold acclimation protein with predicted DNA binding activity (30), was downregulated 1.5-fold in the RNA-Seq and 1.7-fold in the proteomics data set (Table 1). Beyond a role in adaptation to colder temperatures (31,32), and the presence of an Anr box upstream of capB (33), little is known about this gene.…”

Section: Discussionmentioning

confidence: 99%

Overexpression of the Small RNA PA0805.1 in Pseudomonas aeruginosa Modulates the Expression of a Large Set of Genes and Proteins, Resulting in Altered Motility, Cytotoxicity, and Tobramycin Resistance

et al. 2020

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Pseudomonas aeruginosa is a motile species that initiates swarming motility in response to specific environmental cues, i.e., a semisolid surface with amino acids as a nitrogen source (relevant to the human lung). Swarming is an intricately regulated process, but to date posttranscriptional regulation has not been extensively investigated. Small noncoding RNAs (sRNAs) are hypothesized to play posttranscriptional regulatory roles, largely through suppression of translation, and we previously demonstrated 20 sRNA species that were dysregulated under swarming conditions. One of these, sRNA PA0805.1 (which was 5-fold upregulated under swarming conditions), when cloned, transformed into wild-type (WT) PAO1, and overexpressed, led to broad phenotypic changes, including reduced swarming, swimming, and twitching motilities, as well as increased adherence, cytotoxicity, and tobramycin resistance. A ΔPA0805.1 deletion mutant was more susceptible to tobramycin than the WT under swarming conditions. The strain overexpressing PA0805.1 was compared to the empty-vector strain by transcriptome sequencing (RNA-Seq) and proteomics under swarming conditions to determine sRNA targets. Broad transcriptional and proteomic profiles showed 1,121 differentially expressed genes and 258 proteins with significantly different abundance. Importantly, these included 106 transcriptional regulators, two-component regulatory systems, and sigma and anti-sigma factors. Downstream of these regulators were found downregulated type IV pilus genes, many upregulated adherence and virulence factors, and two multidrug efflux systems, mexXY and mexGHI-opmD. Therefore, the sRNA PA0805.1 appears to be a global regulator that influences diverse bacterial lifestyles, most likely through a regulatory cascade. IMPORTANCE P. aeruginosa is an opportunistic pathogen of humans. With roughly 10% of its genes encoding transcriptional regulators, and hundreds of small noncoding RNAs (sRNAs) interspersed throughout the genome, P. aeruginosa is able to fine-tune its response to adapt and survive in the host and resist antimicrobial agents. Understanding mechanisms of genetic regulation is therefore crucial to combat pathogenesis. The previously uncharacterized sRNA PA0805.1 was overexpressed in P. aeruginosa strain PAO1, resulting in decreased motility, increased adherence, cytotoxicity, and tobramycin resistance. In contrast, a ΔPA0805.1 deletion mutant had increased susceptibility to tobramycin under swarming conditions. Omic approaches uncovered 1,121 transcriptomic and 258 proteomic changes in the overexpression strain compared with the empty-vector strain, which included 106 regulatory factors. Downstream of these regulators were upregulated adherence factors, multidrug efflux systems, and virulence factors in both transcriptomics and proteomics. This study provides insights into the role of the sRNA PA0805.1 in modulating bacterial adaptations.

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Core regulon of the global anaerobic regulator Anr targets central metabolism functions in Pseudomonas species

Cited by 26 publications

References 67 publications

Pseudomonas aeruginosa lasR mutant fitness in microoxia is supported by an Anr-regulated oxygen-binding hemerythrin

Pseudomonas aeruginosa lasR mutant fitness in microoxia is supported by an Anr-regulated oxygen-binding hemerythrin

Transcriptome Changes in Pseudomonas putida KT2440 during Medium-Chain-Length Polyhydroxyalkanoate Synthesis Induced by Nitrogen Limitation

Overexpression of the Small RNA PA0805.1 in Pseudomonas aeruginosa Modulates the Expression of a Large Set of Genes and Proteins, Resulting in Altered Motility, Cytotoxicity, and Tobramycin Resistance

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