Pyrimidine Biosynthesis Regulates the Small-Colony Variant and Mucoidy in Pseudomonas aeruginosa through Sigma Factor Competition

Ahmar, Roy Al; Kirby, Brandon D.; Yu, Hongwei D.

doi:10.1128/jb.00575-18

Cited by 15 publications

(9 citation statements)

References 51 publications

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“…aeruginosa is between AlgU and RpoN (a sigma factor regulating nitrogen metabolism, as well as other systems [64]), which have overlapping promoter sites upstream of the alginate biosynthetic gene algD [65]. Shifts in the concentrations of these sigma factors affect algD expression [66]. Furthermore, sigma factor competition between AlgU and the primary sigma factor RpoD has also been suggested [47].…”

Section: Discussionmentioning

confidence: 99%

The anti-sigma factor MucA is required for viability inPseudomonas aeruginosa

Schofield

Rodriguez

Kidman

et al. 2020

Preprint

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Pseudomonas aeruginosa causes chronic lung infections in people with cystic fibrosis (CF), and this bacterium undergoes selection in the CF lung environment over the course of these life-long infections. One genetic adaptation frequently observed in CF P. aeruginosa isolates is mutation of mucA. MucA inhibits the sigma factor AlgU. Clinical mucA mutations lead to misregulation of AlgU, resulting in a mucoid bacterial phenotype that is associated with poor CF disease outcomes. Here we show that paradoxically a portion of the mucA gene is essential for P. aeruginosa viability. We demonstrate that mucA is no longer essential in a strain lacking algU, and mucA alleles that encode for proteins that do not bind to AlgU are insufficient for bacterial viability. Furthermore, we found that mucA is no longer essential in mutant strains containing AlgU variants with reduced sigma factor activity, suggesting that reducing AlgU activity can suppress the requirement for mucA. Finally, we found that overexpression of algU from an inducible promoter prevents cell growth in the absence of MucA, and that this phenotype can be rescued by overproduction of RpoD, the housekeeping sigma factor. Together, these results suggest that in the absence of MucA, the inability to regulate AlgU activity leads to sigma factor competition, preventing the expression of essential housekeeping genes and resulting in the loss of bacterial viability.

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Section: Discussionmentioning

confidence: 99%

The anti-sigma factor MucA is required for viability inPseudomonas aeruginosa

Schofield

Rodriguez

Kidman

et al. 2020

Preprint

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“…Pyrimidine biosynthesis was also found to play a crucial role in the biofilm production phenotype (Garavaglia et al, 2012; Ahmar et al, 2019). In the present study, de novo biosynthesis of pyrimidine is supported by the identification, among others, of orotate phosphoribosyltransferase ( pyr E gene, Q8CSW7).…”

Section: Discussionmentioning

confidence: 99%

Proteomic Analysis Reveals a Biofilm-Like Behavior of Planktonic Aggregates of Staphylococcus epidermidis Grown Under Environmental Pressure/Stress

et al. 2019

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Prosthetic joint replacement failure has a huge impact on quality of life and hospitalization costs. A leading cause of prosthetic joint infection is bacteria-forming biofilm on the surface of orthopedic devices. Staphylococcus epidermidis is an emergent, lowvirulence pathogen implicated in chronic infections, barely indistinguishable from aseptic loosening when embedded in a mature matrix. The literature on the behavior of quiescent S. epidermidis in mature biofilms is scarce. To fill this gap, we performed comparative analysis of the whole proteomic profiles of two methicillin-resistant S. epidermidis strains growing in planktonic and in sessile form to investigate the molecular mechanisms underlying biofilm stability. After 72-h culture of biofilmforming S. epidermidis, overexpression of proteins involved in the synthesis of nucleoside triphosphate and polysaccharides was observed, whereas planktonic bacteria expressed proteins linked to stress and anaerobic growth. Cytological analysis was performed to determine why planktonic bacteria unexpectedly expressed proteins typical of sessile culture. Images evidenced that prolonged culture under vigorous agitation can create a stressful growing environment that triggers microorganism aggregation in a biofilm-like matrix as a mechanism to survive harsh conditions. The choice of a unique late time point provided an important clue for future investigations into the biofilm-like behavior of planktonic cells. Our preliminary results may inform comparative proteomic strategies in the study of mature bacterial biofilm. Finally, there is an increasing number of studies on the aggregation of free-floating bacteria embedded in an extracellular matrix, prompting the need to gain further insight into this mode of bacterial growth.

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“…For experimental purposes, SCV of S. aureus (with the characteristics of clinical SCV) can be selected for in vitro by incubation in the presence of the P. aeruginosa quorum sensing molecule 4-hydroxy-2-heptylquinoline- N -oxide (HQNO) (Hoffman et al, 2006 ), although the authors are not aware whether this works with other staphylococci or other bacterial genera. It was reported that SCV of E. coli could be generated following exposure to 2-methyl-1,4-napthoquinone (Colwell, 1946 ) or copper ions (Weed and Longfellow, 1954 ) and that mutants in a number of bacterial genes can generate SCV (Santos and Hirshfield, 2016 ; Tikhomirova et al, 2018 ; Al Ahmar et al, 2019 ; Vidovic et al, 2019 ). The importance of SCV in the context of infection means that AMP activity vs. SCV could represent an important method for the treatment of chronic, recurrent and antibiotic resistant infections, but has received only limited attention in the context of AMP.…”

Section: Antimicrobial Susceptibility Testing Of Ampmentioning

confidence: 99%

Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy

Mercer

Torres

Duay

et al. 2020

Front. Cell. Infect. Microbiol.

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During the development of antimicrobial peptides (AMP) as potential therapeutics, antimicrobial susceptibility testing (AST) stands as an essential part of the process in identification and optimisation of candidate AMP. Standard methods for AST, developed almost 60 years ago for testing conventional antibiotics, are not necessarily fit for purpose when it comes to determining the susceptibility of microorganisms to AMP. Without careful consideration of the parameters comprising AST there is a risk of failing to identify novel antimicrobials at a time when antimicrobial resistance (AMR) is leading the planet toward a post-antibiotic era. More physiologically/clinically relevant AST will allow better determination of the preclinical activity of drug candidates and allow the identification of lead compounds. An important consideration is the efficacy of AMP in biological matrices replicating sites of infection, e.g., blood/plasma/serum, lung bronchiolar lavage fluid/sputum, urine, biofilms, etc., as this will likely be more predictive of clinical efficacy. Additionally, specific AST for different target microorganisms may help to better predict efficacy of AMP in specific infections. In this manuscript, we describe what we believe are the key considerations for AST of AMP and hope that this information can better guide the preclinical development of AMP toward becoming a new generation of urgently needed antimicrobials.

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Pyrimidine Biosynthesis Regulates the Small-Colony Variant and Mucoidy in Pseudomonas aeruginosa through Sigma Factor Competition

Cited by 15 publications

References 51 publications

The anti-sigma factor MucA is required for viability inPseudomonas aeruginosa

The anti-sigma factor MucA is required for viability inPseudomonas aeruginosa

Proteomic Analysis Reveals a Biofilm-Like Behavior of Planktonic Aggregates of Staphylococcus epidermidis Grown Under Environmental Pressure/Stress

Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy

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