The opportunistic pathogen Pseudomonas aeruginosa exploits bacterial biotin synthesis pathway to benefit its infectivity

Pseudomonas aeruginosa is an opportunistic pathogen that predominantly causes nosocomial and community-acquired lung infections. As a member of ESKAPE pathogens, carbapenem-resistant P. aeruginosa (CRPA) compromises the limited therapeutic options, raising an urgent demand for the development of lead compounds against previously-unrecognized drug targets. Biotin is an important cofactor, of which the de novo synthesis is an attractive antimicrobial target in certain recalcitrant infections. Here we report genetic and biochemical definition of P. aeruginosa BioH (PA0502) that functions as a gatekeeper enzyme allowing the product pimeloyl-ACP to exit from fatty acid synthesis cycle and to enter the late stage of biotin synthesis pathway. In relative to Escherichia coli, P. aeruginosa physiologically requires 3-fold higher level of cytosolic biotin, which can be attributed to the occurrence of multiple biotinylated enzymes. The BioH protein enables the in vitro reconstitution of biotin synthesis. The repertoire of biotin abundance is assigned to different mouse tissues and/or organ contents, and the plasma biotin level of mouse is around 6-fold higher than that of human. Removal of bioH renders P. aeruginosa biotin auxotrophic and impairs its intra-phagosome persistence. Based on a model of CD-1 mice mimicking the human environment, lung challenge combined with systemic infection suggested that BioH is necessary for the full virulence of P. aeruginosa. As expected, the biotin synthesis inhibitor MAC13772 is capable of dampening the viability of CRPA. Notably, MAC13772 interferes the production of pyocyanin, an important virulence factor of P. aeruginosa. Our data expands our understanding of P. aeruginosa biotin synthesis relevant to bacterial infectivity. In particular, this study represents the first example of an extracellular pathogen P. aeruginosa that exploits biotin cofactor as a fitness determinant, raising the possibility of biotin synthesis as an anti-CRPA target. Author summaryCarbapenem-resistant P. aeruginosa (CRPA) is a recalcitrant member of critically-prioritized 'ESKAPE' pathogens, threatening global public health. Bacterial biotin synthesis is recognized as a promising druggable pathway. This study physiologically explained why cytosolic biotin level in P. aeruginosa is relatively-higher than that of E. coli. In addition to its gatekeeper role in biotin synthesis, P. aeruginosa BioH was also found to behave as a fitness determinant. The repertoire of biotin abundance was assigned to an array of mouse tissues and organ contents. Using a model of CD-1 mice that mimics the human plasma environment, lung challenge combined with systemic infection revealed that P. aeruginosa BioH benefits bacterial infectivity. Notably, the biotin synthesis inhibitor MAC13772 can interfere the production of pyocyanin, an important virulence factor in P. aeruginosa. Taken together, our findings provided metabolic insights into P. aeruginosa infection biology, raising the possibility of biotin synthesis as an anti-CRPA target.