Structures and Biosynthesis of Caryoynencins, Unstable Bacterial Polyynes from Pseudomonas protegens Recombinant Expressing the cayG Gene

• Published in: Journal of organic chemistry Vol. 88; no. 23; pp. 16280 - 16291
• Main Authors: Suenaga, Mayuna, Katayama, Naoka, Kitamura, Kokoro, Kai, Kenji
• Format: Journal Article
• Language: English
• Published: United States 01-12-2023
• Subjects: Antifungal Agents - metabolism; Bacteria; Polyynes - metabolism; Pseudomonas - chemistry; Pseudomonas - genetics; Pseudomonas - metabolism
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.3c01789

Bacteria in certain genera can produce "bacterial polyynes" that contain a conjugated C≡C bond starting from a terminal alkyne. Protegenin A is a derivative of octadecanoic acid that contains an ene-tetrayne moiety. It was discovered in
Cab57 and exhibits strong antioomycete and moderate antifungal activity. By introducing
, a cytochrome P450 gene from
, into
Cab57, protegenin A was converted into more complex polyynes, caryoynencins A-E. A purification method that minimized the degradation and isomerization of caryoynencins was established. For the first time, as far as we know, the
H and
C{
H} NMR signals of caryoynencins were completely assigned by analyzing the NMR data of the isolated compounds and protegenin A enriched with [1-
C]- or [2-
C]-acetate. Through the structural analysis of caryoynencins D/E and bioconversion experiments, we observed that CayG constructs the allyl alcohol moiety of caryoynencins A-C through sequential hydroxylation, dehydration, and hydroxylation. The recombinant strain exhibited a stronger antioomycete activity compared to the wild-type strain. This paper proposes a stable purification and structural determination method for various bacterial polyynes, and
Cab57 holds promise as an engineering host for the production of biologically active polyynes.