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Crystal Structure of F. sporotrichioides TRI101 complexed with Coenzyme A and T-2
Structural highlights
FunctionTR101_FUSSP 3-O-acetyltransferase involved in the biosynthesis of trichothecenes, a very large family of chemically related bicyclic sesquiterpene compounds acting as mycotoxins, including T2-toxin (PubMed:11352533, PubMed:17923480). The biosynthesis of trichothecenes begins with the cyclization of farnesyl diphosphate to trichodiene and is catalyzed by the trichodiene synthase TRI5 (PubMed:10583973, PubMed:3800398). Trichodiene undergoes a series of oxygenations catalyzed by the cytochrome P450 monooxygenase TRI4 (PubMed:7651333). TRI4 controls the addition of four oxygens at C-2, C-3, C-11, and the C-12, C-13-epoxide to form the intermediate isotrichotriol (PubMed:16917519). Isotrichotriol then undergoes a non-enzymatic isomerization and cyclization to form isotrichodermol (PubMed:2317042). During this process, the oxygen at the C-2 position becomes the pyran ring oxygen and the hydroxyl group at C-11 is lost (PubMed:2317042). More complex type A trichothecenes are built by modifying isotrichodermol through a series of paired hydroxylation and acetylation or acylation steps (PubMed:11352533). Isotrichodermol is converted to isotrichodermin by the acetyltransferase TRI101 (PubMed:10583973). TRI101 encodes a C-3 transacetylase that acts as a self-protection or resistance factor during biosynthesis and that the presence of a free C-3 hydroxyl group is a key component of Fusarium trichothecene phytotoxicity (PubMed:10583973). A second hydroxyl group is added to C-15 by the trichothecene C-15 hydroxylase TRI11, producing 15-decalonectrin, which is then acetylated by TRI3, producing calonectrin (PubMed:8593041, PubMed:9435078). A third hydroxyl group is added at C-4 by the cytochrome P450 monooxygenase TRI13, converting calonectrin to 3,15-diacetoxyspirpenol, which is subsequently acetylated bythe acetyltransferase TRI7 (PubMed:11352533, PubMed:12135578). A fourth hydroxyl group is added to C-8 by the cytochrome P450 monooxygenase TRI1, followed by the addition of an isovaleryl moiety by TRI16 (PubMed:12620849, PubMed:14532047). Finally, the acetyl group is removed from the C-3 position by the trichothecene C-3 esterase TRI8 to produce T-2 toxin (PubMed:12039755).[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedFusarium head blight (FHB) is a plant disease with serious economic and health impacts. It is caused by fungal species belonging to the genus Fusarium and the mycotoxins they produce. Although it has proved difficult to combat this disease, one strategy that has been examined is the introduction of an indigenous fungal protective gene into cereals such as wheat barley and rice. Thus far the gene of choice has been tri101 whose gene product catalyzes the transfer of an acetyl group from acetyl coenzyme A to the C3 hydroxyl moiety of several trichothecene mycotoxins. In vitro this has been shown to reduce the toxicity of the toxins by approximately 100-fold but has demonstrated limited resistance to FHB in transgenic cereal. To understand the molecular basis for the differences between in vitro and in vivo resistance the three-dimensional structures and kinetic properties of two TRI101 orthologs isolated from Fusarium sporotrichioides and Fusarium graminearum have been determined. The kinetic results reveal important differences in activity of these enzymes toward B-type trichothecenes such as deoxynivalenol. These differences in activity can be explained in part by the three-dimensional structures for the ternary complexes for both of these enzymes with coenzyme A and trichothecene mycotoxins. The structural and kinetic results together emphasize that the choice of an enzymatic resistance gene in transgenic crop protection strategies must take into account the kinetic profile of the selected protein. Structural and functional characterization of the TRI101 trichothecene 3-O-acetyltransferase from Fusarium sporotrichioides and Fusarium graminearum: kinetic insights to combating Fusarium head blight.,Garvey GS, McCormick SP, Rayment I J Biol Chem. 2008 Jan 18;283(3):1660-9. Epub 2007 Oct 8. PMID:17923480[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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