Genome Mining Discovery of Protegenins A–D, Bacterial Polyynes Involved in the Antioomycete and Biocontrol Activities of Pseudomonas protegens

• Published in: ACS chemical biology 2022-12, Vol.17 (12), p.3313-3320
• Main Authors: Murata, Kazuya, Suenaga, Mayuna, Kai, Kenji
• Format: Article
• Language: English
• Subjects: Cucumis sativus - genetics; Cucumis sativus - microbiology; Multigene Family; Polyynes; Pseudomonas - genetics
• ISSN: 1554-8929; 1554-8937
• DOI: 10.1021/acschembio.1c00276

Some bacteria uniquely produce “bacterial polyynes”, which possess a conjugated CC bond starting with a terminal alkyne, and use them as chemical weapons against hosts and competitors. Pseudomonas protegens Cab57, a biocontrol agent against plant pathogens, has an orphan biosynthetic gene cluster for bacterial polyynes (named protegenins). In this study, the isolation, structure elucidation, and biological characterization of protegenins A–D are reported. The structures of protegenins A–D determined by spectroscopic and chemical techniques were octadecanoic acid derivatives possessing an ene–tetrayne, ene–triyne–ene, or ene–triyne moiety. The protegenins exhibited weak to strong antioomycete activity against Pythium ultimum OPU774. The deletion of proA, a protegenin biosynthetic gene, resulted in the reduction of the antioomycete activity of P. protegens. The Gac/Rsm system, a quorum sensing-like system of Pseudomonas bacteria, regulated the production of protegenins. The production profile of protegenins was dependent on the culturing conditions, suggesting a control mechanism for protegenin production selectivity. P. protegens suppressed the damping-off of cucumber seedlings caused by P. ultimum, and this protective effect was reduced in the proA-deletion mutant. Altogether, protegenins are a new class of bacterial polyynes which contribute to the antioomycete and plant-protective effects of P. protegens.