Structural and functional characterization of TRI3 trichothecene 15‐O‐acetyltransferase from Fusarium sporotrichioides

Abstract

Fusarium head blight is a devastating disease of cereal crops whose worldwide incidence is increasing and at present there is no satisfactory way of combating this pathogen or its associated toxins. There is a wide variety of trichothecene mycotoxins and they all contain a 12,13-epoxytrichothecene skeleton but differ in their substitutions. Indeed, there is considerable variation in the toxin profile across the numerous Fusarium species that has been ascribed to differences in the presence or absence of biosynthetic enzymes and their relative activity. This article addresses the source of differences in acetylation at the C15 position of the trichothecene molecule. Here, we present the in vitro structural and biochemical characterization of TRI3, a 15-O-trichothecene acetyltransferase isolated from F. sporotrichioides and the ''in vivo'' characterization of Dtri3 mutants of deoxynivalenol (DON) producing F. graminearum strains. A kinetic analysis shows that TRI3 is an efficient enzyme with the native substrate, 15-decalonectrin, but is inactive with either DON or nivalenol. The structure of TRI3 complexed with 15-decalonectrin provides an explanation for this specificity and shows that Tri3 and Tri101 (3-O-trichothecene acetyltransferase) are evolutionarily related. The active site residues are conserved across all sequences for TRI3 orthologs, suggesting that differences in acetylation at C15 are not due to differences in Tri3. The tri3 deletion mutant shows that acetylation at C15 is required for DON biosynthesis even though DON lacks a C15 acetyl group. The enzyme(s) responsible for deacetylation at the 15 position of the trichothecene mycotoxins have not been identified.

Targeted Disruption of Transcriptional Regulators inChaetomium globosumActivates Biosynthetic Pathways and Reveals Transcriptional Regulator-Like Behavior of Aureonitol

“…Lastly, the nascent chain is released by its terminal reductase domain as a cyclized aldehyde. Subsequent involvement of CHGG_10023 (enoyl Journal of the American Chemical Society Acetylation of the alcohol group on the ring system can be achieved by CHGG_10028, a predicted O-acetyltransferase, 56 and dimerization is likely performed by a fungal laccase-like CHGG_10025. 57 Biosynthetic Pathway of Chaetoglocin 5 and Coarctatins 11 and 12.…”

Hydroxycinnamoyltransferases in plant metabolism

“…The phylogenetic tree was constructed with help of the maximum likelihood method with 1000 bootstraps using the MEGA6 software (Tamura et al 2013). HST/HQT hydroxycinnamoyl-CoA:shikimate/quinate HCT (filled square), Other structurally investigated enzymes of this superfamily are an anthocyanin malonyltransferase from Dendranthema morifolium (pdb 3e1t, 2e1u, 2e1v; Unno et al 2007) and a fungal enzyme, trichothecene 15-O-acetyltransferase from Fusarium sporotrichioides and from F. graminearum (pdb 3fp0, 3fot, 2rkt, 2rkv, 2zba, 3b2s, 3b30;Garvey et al 2008Garvey et al , 2009. Sonnante et al (2010) modelled two HQTs and one HCT from artichoke on the basis of the known structures from the two above-mentioned plant enzymes.…”

Cloning and functional characterization of two monoterpene acetyltransferases from glandular trichomes of L. x intermedia.

“…The intermediate is subsequently reprotonated to produce the free CoA and the acetylated ester or amide (D'Auria 2006). The second highly conserved region is the DFGWG motif, which is located at the carboxyl end of the protein, and is believed to have a structural role in enzymatic function (D'Auria 2006;Garvey et al 2009;Unno et al 2007). Nearly all functionally characterized BAHD enzymes contain both of these motifs, and deletion or modification of one or both of these motifs result in highly reduced enzyme activity (D'Auria 2006;Unno et al 2007).…”