Protein engineering in designing tailored enzymes and microorganisms for biofuels production

Abstract

SummaryLignocellulosic biofuels represent a sustainable, renewable, and the only foreseeable alternative energy source to transportation fossil fuels. However, the recalcitrant nature of lignocellulose poses technical hurdles to an economically viable biorefinery. Low enzymatic hydrolysis efficiency and low productivity, yield, and titer of biofuels are among the top cost contributors. Protein engineering has been used to improve the performances of lignocellulose-degrading enzymes, as well as proteins involved in biofuel synthesis pathways. Unlike its great success seen in other industrial applications, protein engineering has achieved only modest results in improving the lignocellulose-to-biofuels efficiency. This review will discuss the unique challenges that protein engineering faces in the process of converting lignocellulose to biofuels and how they are addressed by recent advances in this field.

Tracing Determinants of Dual Substrate Specificity in Glycoside Hydrolase Family 5

“…Although there are no reports in the literature for enzymatic activity enhancement for mannan hydrolysis, the largest improvements for glucan and xylan hydrolysis to date are ϳ80% (35) and ϳ300% (36), respectively. That the 300% increase in specific mannanase activity and 1,600% improvement in mannanase k cat /K m observed for the "back-to-motif" mutation in Cel5B_Dtu come from a point mutant is intriguing given the difficulty of enhancing activity in these enzymes through other optimization techniques (37)(38)(39). The back-to-motif mutation indicates that this substrate-determining motif could be ancestral to the GH5 family, supporting Jensen's hypothesis (40) that the spectrum of specificity in the ancestors of an enzyme family can be seen in the descendant families.…”

Bioethanol: Feedstock Alternatives, Pretreatments, Lignin Chemistry, and the Potential for Green Value-Added Lignin Co-Products

“…Biological pretreatments may be either abiotic (i.e., the use of enzymes) or biotic (i.e., microbial-based). Several reviews on the use of naturally-derived as well as engineered enzymes for lignocellulose deconstruction have been published [111][112][113]. In fact, there are companies with the sole purpose of designing and developing enzymes for bioethanol production processes.…”

Protein Engineering Methods and Applications

“…Particularly, obtaining biofuels from lignocellulosic resources is a challenge, as the enzyme hydrolysis efficiency of lignocellulose is low which increases the costs of biofuels. Thus, protein engineering methods have been used to improve the performance of lignocellulose-degrading enzymes, and biofuels-synthesizing enzymes (Wen et al, 2009). Protein engineering is also applied to obtain an efficient electrical communication between biocatalyst(s) and the electrode by rational design and directed evolution, within the frame of biocatalyst engineering (Guven et al, 2010).…”