Pyrichalasin H biosynthesis cluster protein E . Hydrolyase; part of the gene cluster that mediates the biosynthesis of the mycotoxin pyrichalasin H, a tyrosine-derived cytochalasan that inhibits the growth of rice seedlings, but also inhibits lymphocyte capping and actin polymerization and alters cell morphology. After PyiS PyiC and before PyiF. FUS2 hydrolase family
(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Opisthokonta: NE > Fungi: NE > Dikarya: NE > Ascomycota: NE > saccharomyceta: NE > Pezizomycotina: NE > leotiomyceta: NE > sordariomyceta: NE > Sordariomycetes: NE > Sordariomycetidae: NE > Magnaporthales: NE > Magnaporthaceae: NE > Magnaporthe: NE > Magnaporthe grisea: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MHKFFPRSGFFDFETVRILGTACYGGADVAEVLEAVGEIKSDDAASWEEA WRRQSWWAEALADQAREGGDREAARRAYLRASNYARASGYMYVSDLGAEG GNAPPTQDPRALPVAEKVGRLFRKALALMEGEVRALSIPCGAQALPGLLY LPPPGKRIPGRDKIPVLVFLGGADSCQEELYYLYPAAGPGLGYAVLTFDG PGQGIVLRKHGLRVRPDWEVVTSSVLDYLEAYSAQHPGLELDMKAIAVSG ASMGGYYALRSAVDRRVKACVSIDPFYDMWDFGTAHVSPLFISAWTSGII SSGFVDKLMTVVSRLWFQMKWEIALTGTLFGLSSPSQILLNMKNYTLSGK SDGSRANGKKSHSPTDGGGVESDSFLSEVRCPVFLSGAGKSLYLDVDSHT RRCYDGLTGVAAKDKELWVPESEGQGSLQAKMGALALCNQKTFQFLDKVL GVQRVPLDVSAHI
References
Title: Chemical and Genetic Studies on the Formation of Pyrrolones During the Biosynthesis of Cytochalasans Zhang H, Hantke V, Bruhnke P, Skellam E, Cox RJ Ref: Chemistry, 10:3106, 2021 : PubMed
A key step during the biosynthesis of cytochalasans is a proposed Knoevenagel condensation to form the pyrrolone core, enabling the subsequent 4+2 cycloaddition reaction that results in the characteristic octahydroisoindolone motif of all cytochalasans. Here we investigate the role of the highly conserved alpha-beta -hydrolase enzymes PyiE and ORFZ during the biosynthesis of pyrichalasin H and the ACE1 metabolite respectively, using gene knockout and complementation techniques. Using synthetic aldehyde models we demonstrate that the Knoevenagel condensation proceeds spontaneously but results in the 1,3-dihydro-2H-pyrrol-2-one tautomer, rather than the required 1,5-dihydro-2H-pyrrol-2-one tautomer. Taken together our results suggest that the alpha-beta -hydrolase enzymes are essential for first ring cyclisation, but the precise nature of the intermediates remains to be determined .
Title: Targeted Gene Inactivations Expose Silent Cytochalasans in Magnaporthe grisea NI980 Wang C, Hantke V, Cox RJ, Skellam E Ref: Org Lett, 21:4163, 2019 : PubMed
The biosynthetic gene cluster encoding the phytotoxin pyrichalasin H 5 was discovered in Magnaporthe grisea NI980, and the late-stage biosynthetic pathway of 5 was fully elucidated using targeted gene inactivations resulting in the isolation of 13 novel cytochalasans. This study reveals that the nonproteinogenic amino acid O-methyltyrosine is the true precursor of 5, and other cryptic cytochalasans and mutasynthesis experiments produce novel halogenated pyrichalasin H analogues.
Tailoring enzymes in cytochalasan biosynthesis are relatively promiscuous. Exploiting this property, we deduced the function of four cryptic cytochrome P450 monooxygenases via heterologous expression of six cytochrome P450-encoding genes, originating from Hypoxylon fragiforme and Pyricularia oryzae, in pyrichalasin H deltaP450 strains. Three cryptic cytochrome P450 enzymes (HffD, HffG, and CYP1) restored pyrichalasin H production in mutant strains, while CYP3 catalyzed a site-selective epoxidation leading to the isolation of three novel cytochalasans.
