title: Over-expression of xylulokinase in a xylose-metabolising recombinant strain of Zymomonas mobilis.
abstract: The broad host range vector pBBR1MCS-2 has been evaluated as an expression vector for Zymomonas mobilis. The transformation efficiency of this vector was 2 x 10(3) CFU per mug of DNA in a recombinant strain of Z. mobilis ZM4/AcR containing the plasmid pZB5. Stable replication for this expression vector was demonstrated for 50 generations. This vector was used to study xylose metabolism in acetate resistant Z. mobilis ZM4/AcR (pZB5) by over-expression of xylulokinase (XK), as previous studies had suggested that XK could be the rate-limiting enzyme for such strains. Based on the above vector, a recombinant plasmid pJX1 harboring xylB (expressing XK) under control of a native Z. mobilis promotor Ppdc was constructed. When this plasmid was introduced into ZM4/AcR (pZB5) a 3-fold higher XK expression was found compared to the control strain. However, fermentation studies with ZM4/AcR (pZB5, pJX1) on xylose medium did not result in any increase in rate of growth or xylose metabolism, suggesting that XK expression was not rate-limiting for ZM4/AcR (pZB5) and related strains.
authors.affiliation: School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.
authors.forename: Young Jae
authors.initials: YJ
authors.lastname: Jeon
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Svenson
authors.forename: Peter L
authors.initials: PL
authors.lastname: Rogers
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D005285:Fermentation; D015870:Gene Expression; D005798:Genes, Bacterial; D005822:Genetic Vectors; D007700:Kinetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D011995:Recombination, Genetic; D014994:Xylose / Q000378:metabolism*; D017355:Zymomonas / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D014994:Xylose; D017853:Phosphotransferases (Alcohol Group Acceptor); C032700:xylulokinase