Lignin is a complex aromatic polymer in plant cell walls that is essential to their function. However, due to its cross-linking with other cell wall polymers and strong bonds between subunits, lignin is a major contributor to cell wall recalcitrance, inhibiting polysaccharide utilization. One strategy to overcome this hurdle is to introduce more easily cleavable ester linkages into the lignin backbone to allow for breakdown at lower temperatures and pressures. This is especially important in the biofuels industries where lignocellulosic biomass is a major source of polysaccharides for ethanol fermentation. Two enzymes in particular, feruloyl-CoA:monolignol transferase (FMT) and p-coumaroyl-CoA:monolignol transferase (PMT), have been identified which catalyze the acylation of monolignols, producing monolignol hydroxycinnamate ester conjugates. Here we report homology models of both PMT and FMT. Both models have the two-domain fold typical of the BAHD acyl-transferase superfamily with the proposed active site located in a solvent channel between the two domains. Both proteins have been expressed and purified in E. coli. While ongoing crystallization trials are being conducted these computational models will aid in the understanding and characterization of these enzymes for use in the biofuels industry.

Homology models of two BAHD acetyl-transferase enzymes important in lignin biosynthesis

247th National Meeting (2014)

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