title: Characterization and evolution of xylose isomerase screened from the bovine rumen metagenome in Saccharomyces cerevisiae.
abstract: The conversion of abundant levels of xylose in lignocellulosic materials into viable products would generate economic benefits. The heterologous expression of the xylose isomerase (XI) gene is considered a direct and effective strategy for establishing the xylose metabolic pathway in Saccharomyces cerevisiae. However, only limited sources of xylA are functionally expressed in S. cerevisiae and are capable of driving effective xylose consumption. In this study, Ru-xylA (where Ru represents the rumen), which was screened from the contents of the bovine rumen metagenomic library, was functionally expressed in S. cerevisiae, and the enzyme activity was 1.31 U mg(-1) protein. This is a new source of XI that can exhibit high activity levels in S. cerevisiae. The activity of this enzyme is comparable to those of the Piromyces sp. XI. Then, the Ru-XI activity was further improved through mutagenesis and growth-based screening in a centromeric plasmid. A variant containing two mutations (K11T/D220V) that exhibited a 68% increase in enzyme activity was isolated. Our work identified a new xylose isomerase that can be functionally expressed in S. cerevisiae and results in a higher XI enzyme activity through mutagenesis.
authors.affiliation: The State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Hou
authors.affiliation: The State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.affiliation: The State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Jiao
authors.affiliation: The State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
authors.forename: Ruilei
authors.initials: R
authors.lastname: Ge
authors.affiliation: The State Key Laboratory of Microbial Technology, Shandong University, Jinan, China.
authors.forename: Xingjing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: The State Key Laboratory of Microbial Technology, Shandong University, Jinan, China. Electronic address: bxm@sdu.edu.cn.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Bao
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D005075:Biological Evolution; D002417:Cattle; D015870:Gene Expression; D054892:Metagenome / Q000235:genetics*; D016296:Mutagenesis; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D020089:Piromyces / Q000201:enzymology; D012417:Rumen / Q000201:enzymology* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism
chemical_list: D050505:Mutant Proteins; D014994:Xylose; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase
keywords: Bovine rumen metagenome; Budding yeast; Ethanol; Growth-based screening; Xylose isomerase