Deacidification by FhlA-dependent hydrogenase is involved in urease activity and urinary stone formation in uropathogenic Proteus mirabilis

Abstract

Proteus mirabilis is an important uropathogen, featured with urinary stone formation. Formate hydrogenlyase (FHL), consisting of formate dehydrogenase H and hydrogenase for converting proton to hydrogen, has been implicated in virulence. In this study, we investigated the role of P. mirabilis FHL hydrogenase and the FHL activator, FhlA. fhlA and hyfG (encoding hydrogenase large subunit) displayed a defect in acid resistance. fhlA and hyfG mutants displayed a delay in medium deacidification compared to wild-type and ureC mutant failed to deacidify the medium. In addition, loss of fhlA or hyfG decreased urease activity in the pH range of 5–8. The reduction of urease activities in fhlA and hyfG mutants subsided gradually over the pH range and disappeared at pH 9. Furthermore, mutation of fhlA or hyfG resulted in a decrease in urinary stone formation in synthetic urine. These indicate fhlA- and hyf-mediated deacidification affected urease activity and stone formation. Finally, fhlA and hyfG mutants exhibited attenuated colonization in mice. Altogether, we found expression of fhlA and hyf confers medium deacidification via facilitating urease activity, thereby urinary stone formation and mouse colonization. The link of acid resistance to urease activity provides a potential strategy for counteracting urinary tract infections by P. mirabilis.

Differential contribution of hydrogen metabolism to Proteus mirabilis fitness during single-species and polymicrobial catheterized urinary tract infection

“…Both the Hyb and Hyf [NiFe] hydrogenases are thought to contribute to membrane potential and proton motive force in other bacterial species (Schoelmerich & Müller, 2020, Vignais & Billoud, 2007. In agreement with this hypothesis, Lin et al reported that the Hyf system contributes to P. mirabilis acid tolerance (Lin & Liaw, 2020), which we have found to be a reliable surrogate for assessing alterations in membrane potential (Armbruster et al , 2014, Brauer et al , 2022. We therefore sought to determine the contribution of each hydrogenase to acid tolerance in P. mirabilis strain HI4320.…”

“…[NiFe] hydrogenases do not contribute to urease activity,acid tolerance, or motility in P. mirabilis strain HI4320 . Lin et al previously demonstrated that the Hyf system contributes to optimal urease activity of P. mirabilis at low pH (Lin & Liaw, 2020). Specifically, disrupting hyfG in P. mirabilis strain N2 largely resulted in decreased urease activity in synthetic urine at acidic to neutral pH.…”

“…Genes within the hyf cluster were significantly upregulated in a mouse model of ascending UTI, and we also previously identified them as core fitness factors by transposon insertion-site sequencing of P. mirabilis single-species CAUTI and polymicrobial CAUTI with P. stuartii, suggesting an important contribution to infection (Pearsonet al , 2011, Armbruster et al , 2017a. Furthermore, recent work by Lin et al demonstrated that the hydrogenase large subunit (hyfG ) and formate hydrogen lyase (fylA ) contribute to P. mirabilis acid tolerance, urease activity at low pH, and urinary tract colonization in a mouse model of ascending UTI (Lin & Liaw, 2020). Although the direct contribution to hydrogenase activity has never been directly assessed in P. mirabilis , the collective data suggest that Hyf represents an important fitness factor for P. mirabilis urinary tract infection.…”

Antibiotic susceptibility is associated with some of the virulence associated genes in Proteus isolates

“…Proteus mirabilis is the third most common pathogen which is isolated (after Escherichia coli and Klebsiella pneumonia) from urinary tract infections. It also is the leading cause bacterium in catheter-associated urinary tract infections (CAUTI) that usually associated with formation of urinary stones and the obstruction of urinary catheters [9,10].…”

Differential Contribution of Hydrogen Metabolism to Proteus mirabilis Fitness during Single-Species and Polymicrobial Catheterized Urinary Tract Infection

“…The [NiFe] hydrogenases in pathogenic bacteria have been classified into at least 13 subgroups based on properties such as their genetic organization, localization, redox partners, oxygen tolerance, and activity [17][18][19]. P. mirabilis HI4320 encodes two putative [NiFe] hydrogenases: a Hyb-type Group 1c hydrogenase predicted to oxidize H 2 and generate PMF through respiration of fumarate or other highpotential oxidants [20], and a Hyf-type Group 4a hydrogenase that was recently confirmed to contribute to P. mirabilis acid tolerance through formate-dependent production of H 2 [21].…”