Lee Charles C, Kibblewhite Rena E, Paavola Chad D, Orts William J, Wagschal Kurt
Bioproducts Research Unit, USDA-ARS-WRRC, 800 Buchanan St., Albany, CA, 94710, USA.
NASA Ames Research Center, Moffett Field, CA, 94035, USA.
Mol Biotechnol. 2016 Jul;58(7):489-96. doi: 10.1007/s12033-016-9945-y.
Hemicellulose biomass is a complex polymer with many different chemical constituents that can be utilized as industrial feedstocks. These molecules can be released from the polymer and transformed into value-added chemicals through multistep enzymatic pathways. Some bacteria produce cellulosomes which are assemblies composed of lignocellulolytic enzymes tethered to a large protein scaffold. Rosettasomes are artificial engineered ring scaffolds designed to mimic the bacterial cellulosome. Both cellulosomes and rosettasomes have been shown to facilitate much higher rates of biomass hydrolysis compared to the same enzymes free in solution. We investigated whether tethering enzymes involved in both biomass hydrolysis and oxidative transformation to glucaric acid onto a rosettasome scaffold would result in an analogous production enhancement in a combined hydrolysis and bioconversion metabolic pathway. Three different enzymes were used to hydrolyze birchwood hemicellulose and convert the substituents to glucaric acid, a top-12 DOE value added chemical feedstock derived from biomass. It was demonstrated that colocalizing the three different enzymes to the synthetic scaffold resulted in up to 40 % higher levels of product compared to uncomplexed enzymes.
半纤维素生物质是一种具有多种不同化学成分的复杂聚合物，可作为工业原料。这些分子可以从聚合物中释放出来，并通过多步酶促途径转化为增值化学品。一些细菌产生纤维小体，它是由与大蛋白质支架相连的木质纤维素分解酶组成的组件。玫瑰花结小体是人工设计的环形支架，旨在模仿细菌纤维小体。与溶液中游离的相同酶相比，纤维小体和玫瑰花结小体都已被证明能促进更高速率的生物质水解。我们研究了将参与生物质水解和氧化转化为葡萄糖二酸的酶连接到玫瑰花结小体支架上，是否会在联合水解和生物转化代谢途径中产生类似的产量提高。使用三种不同的酶来水解桦木木聚糖，并将取代基转化为葡萄糖二酸（一种源自生物质的美国能源部前12种增值化学原料）。结果表明，与未复合的酶相比，将这三种不同的酶共定位到合成支架上可使产物水平提高高达40%。
