title: Functional Characterization of Corynebacterium alkanolyticum β-Xylosidase and Xyloside ABC Transporter in Corynebacterium glutamicum.
abstract: The Corynebacterium alkanolyticum xylEFGD gene cluster comprises the xylD gene that encodes an intracellular β-xylosidase next to the xylEFG operon encoding a substrate-binding protein and two membrane permease proteins of a xyloside ABC transporter. Cloning of the cluster revealed a recombinant β-xylosidase of moderately high activity (turnover for p-nitrophenyl-β-d-xylopyranoside of 111 ± 4 s(-1)), weak α-l-arabinofuranosidase activity (turnover for p-nitrophenyl-α-l-arabinofuranoside of 5 ± 1 s(-1)), and high tolerance to product inhibition (Ki for xylose of 67.6 ± 2.6 mM). Heterologous expression of the entire cluster under the control of the strong constitutive tac promoter in the Corynebacterium glutamicum xylose-fermenting strain X1 enabled the resultant strain X1EFGD to rapidly utilize not only xylooligosaccharides but also arabino-xylooligosaccharides. The ability to utilize arabino-xylooligosaccharides depended on cgR_2369, a gene encoding a multitask ATP-binding protein. Heterologous expression of the contiguous xylD gene in strain X1 led to strain X1D with 10-fold greater β-xylosidase activity than strain X1EFGD, albeit with a total loss of arabino-xylooligosaccharide utilization ability and only half the ability to utilize xylooligosaccharides. The findings suggest some inherent ability of C. glutamicum to take up xylooligosaccharides, an ability that is enhanced by in the presence of a functional xylEFG-encoded xyloside ABC transporter. The finding that xylEFG imparts nonnative ability to take up arabino-xylooligosaccharides should be useful in constructing industrial strains with efficient fermentation of arabinoxylan, a major component of lignocellulosic biomass hydrolysates.
authors: Research Institute of Innovative Technology for the Earth, Kizugawa-shi, Kyoto, Japan.
authors: Akira
authors: A
authors: Watanabe
authors: Research Institute of Innovative Technology for the Earth, Kizugawa-shi, Kyoto, Japan.
authors: Kazumi
authors: K
authors: Hiraga
authors: Research Institute of Innovative Technology for the Earth, Kizugawa-shi, Kyoto, Japan.
authors: Masako
authors: M
authors: Suda
authors: Research Institute of Innovative Technology for the Earth, Kizugawa-shi, Kyoto, Japan.
authors: Hideaki
authors: H
authors: Yukawa
authors: Research Institute of Innovative Technology for the Earth, Kizugawa-shi, Kyoto, Japan Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan mmg-lab@rite.or.jp.
authors: Masayuki
authors: M
authors: Inui
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D003001:Cloning, Molecular; D003352:Corynebacterium / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005285:Fermentation; D005965:Glucuronates / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D006027:Glycosides / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D009844:Oligosaccharides / Q000378:metabolism; D009876:Operon; D014990:Xylans / Q000378:metabolism; D014994:Xylose / Q000378:metabolism; D014995:Xylosidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; C090796:ATP-binding protein, bacteria; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005965:Glucuronates; D006027:Glycosides; D009844:Oligosaccharides; D014990:Xylans; C570991:xylooligosaccharide; C010807:xylosides; C085118:arabinoxylan; D014994:Xylose; D006026:Glycoside Hydrolases; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase; C019713:alpha-N-arabinofuranosidase