Deletion of xylR gene enhances expression of xylose isomerase in Streptomyces lividans TK24

Gun Young Heo, Won Chan Kim, Gil Jae Joo, Yun Young Kwak, Jae Ho Shin, Dong Hyun Roh, Heui Dong Park, In Koo Rhee

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14 Scopus citations

Abstract

Glucose (xylose) isomerases from Streptomyces sp. have been used for the production of high fructose corn syrup for industrial purposes. An 11-kb DNA fragment containing the xyl gene cluster was isolated from Streptomyces lividans TK24 and its nucleotide sequences were analyzed. It was found that the xyl gene cluster contained a putative transcriptional repressor (xylR), xylulokinase (xylB), and xylose isomerase (xylA) genes. The transcriptional directions of the xylB and xylA genes were divergent, which is consistent to those found in other streptomycetes. A gene encoding XylR was located downstream of the xylB gene in the same direction, and its mutant strain produced xylose isomerase regardless of xylose in the media. The enzyme expression level in the mutant was 4.6 times higher than that in the parent strain under xylose-induced condition. Even in the absence of xylose, the mutant strain produce over 60% of enzyme compared with the xylose-induced condition. Gel mobility shift assay showed that XyIR was able to bind to the putative xyl promoter, and its binding was inhibited by the addition of xylose in vitro. This result suggested that XylR acts as a repressor in the S. lividans xylose operon.

Original languageEnglish
Pages (from-to)837-844
Number of pages8
JournalJournal of Microbiology and Biotechnology
Volume18
Issue number5
StatePublished - 28 May 2008

Keywords

  • Gene disruption
  • Glucose (Xylose) isomemse
  • Streptomyces lividans
  • xyl operon
  • xylR

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