Distinct Screening Approaches Uncover PA14_36820 and RecA as Negative Regulators of Biofilm Phenotypes in Pseudomonas aeruginosa PA14

Yahya, Amal H; Harston, Sophie R; Colton, William L; Cabeen, Matthew T.

doi:10.1128/spectrum.03774-22

Cited by 2 publications

(1 citation statement)

References 67 publications

(86 reference statements)

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“…Full transcriptomic data sets comparing strains with and without ptsP , including the raw sequence reads for PA14 ∆ amrZ ∆ ptsP , have been deposited in the Gene Expression Omnibus at NCBI under accession number GSE239971 . Control data sets comprising PA14 and PA14 ∆ amrZ samples were previously published under accession number GSE226104 ( 48 ).…”

Section: Data Availabilitymentioning

confidence: 99%

A putative lipase affects Pseudomonas aeruginosa biofilm matrix production

Pan,

Erdmann,

Terrell

et al. 2023

mSphere

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Pseudomonas aeruginosa is an opportunistic pathogen that is widely known for infecting patients with underlying conditions. This species often survives antibiotic therapy by forming biofilms, in which the cells produce a protective extracellular matrix. P. aeruginosa also produces virulence factors that enhance its ability to cause disease. One signaling pathway that influences virulence is the nitrogen-related phosphotransferase system (Nitro-PTS), which consists of an initial phosphotransferase, PtsP , a phosphocarrier, PtsO, and a terminal phosphate receptor, PtsN. The physiological role of the Nitro-PTS in P. aeruginosa is poorly understood. However, PtsN, when deprived of its upstream phosphotransfer proteins, has an antagonistic effect on biofilm formation. We thus conducted a transposon mutagenesis screen in an unphosphorylated-PtsN (i.e., ∆ ptsP ) background to identify downstream proteins with unacknowledged roles in PtsN-mediated biofilm suppression. We found an unstudied gene, PA14_04030 , whose disruption restored biofilm production. This gene encodes a predicted phospholipase with signature alpha/beta hydrolase folds and a lipase signature motif with an active-site Ser residue. Hence, we renamed the gene bipL , for b iofilm- i mpacting p hospho l ipase. Deletion of bipL in a ∆ ptsP background increased biofilm formation, supporting the idea that BipL is responsible for reducing biofilm formation in strains with unphosphorylated PtsN. Moreover, substituting the putative catalytic Ser for Ala phenocopied bipL deletion, indicating that this residue is important for the biofilm-suppressive activity of BipL in vivo . As our preliminary data suggest that BipL is a lipase, we performed lipidomics to detect changes in the lipid profile due to bipL deletion and found changes in some lipid species. IMPORTANCE Biofilm formation by bacteria occurs when cells secrete an extracellular matrix that holds them together and shields them from environmental insults. Biofilms of bacterial opportunistic human pathogens such as Pseudomonas aeruginosa pose a substantial challenge to clinical antimicrobial therapy. Hence, a more complete knowledge about the bacterial factors that influence and regulate production of the biofilm matrix is one key to formulate more effective therapeutic strategies. In this study, we screen for factors that are important for reducing biofilm matrix production in certain genetic backgrounds. We unexpectedly found a gene encoding a putative lipase enzyme and showed that its predicted catalytic site is important for its ability to reduce biofilm formation. Our findings suggest that lipase enzymes have previously uncharacterized functions in biofilm matrix regulation.

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Section: Data Availabilitymentioning

confidence: 99%

A putative lipase affects Pseudomonas aeruginosa biofilm matrix production

Pan,

Erdmann,

Terrell

et al. 2023

mSphere

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Nutrient Requirements Shape the Preferential Habitat of Allorhizobium vitis VAR03-1, a Commensal Bacterium, in the Rhizosphere of Arabidopsis thaliana

Hemelda,

Bao,

Watanabe

et al. 2024

Plant and Cell Physiology

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A diverse range of commensal bacteria inhabit the rhizosphere, influencing host plant growth and responses to biotic and abiotic stresses. While root-released nutrients can define soil microbial habitats, the bacterial factors involved in plant-microbe interactions are not well characterized. In this study, we investigated the colonization patterns of two plant disease biocontrol agents, Allorhizobium vitis VAR03-1 and Pseudomonas protegens Cab57, in the rhizosphere of Arabidopsis thaliana using Murashige and Skoog (MS) agar medium. VAR03-1 formed colonies even at a distance from the roots, preferentially in the upper part, while Cab57 colonized only the root surface. The addition of sucrose to the agar medium resulted in excessive proliferation of VAR03-1, similar to its pattern without sucrose, whereas Cab57 formed colonies only near the root surface. Overgrowth of both bacterial strains upon nutrient supplementation inhibited host growth, independent of plant immune responses. This inhibition was reduced in the VAR03-1 ΔrecA mutant, which exhibited increased biofilm formation, suggesting that some activities associated with the free-living lifestyle rather than the sessile lifestyle may be detrimental to host growth. VAR03-1 grew in liquid MS medium with sucrose alone, while Cab57 required both sucrose and organic acids. Supplementation of sugars and organic acids allowed both bacterial strains to grow near and away from Arabidopsis roots in MS agar. These results suggest that nutrient requirements for bacterial growth may determine their growth habitats in the rhizosphere, with nutrients released in root exudates potentially acting as a limiting factor in harnessing microbiota.

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Distinct Screening Approaches Uncover PA14_36820 and RecA as Negative Regulators of Biofilm Phenotypes in Pseudomonas aeruginosa PA14

Abstract: Pseudomonas aeruginosa is a notorious human pathogen well known for forming biofilms, communities of bacteria that protect themselves within a self-secreted matrix. Here, we sought to find genetic determinants that impacted biofilm matrix production in P. aeruginosa strains.

Cited by 2 publications

References 67 publications

A putative lipase affects Pseudomonas aeruginosa biofilm matrix production

A putative lipase affects Pseudomonas aeruginosa biofilm matrix production

Nutrient Requirements Shape the Preferential Habitat of Allorhizobium vitis VAR03-1, a Commensal Bacterium, in the Rhizosphere of Arabidopsis thaliana

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