The membrane-bound alpha-glucuronidase from Pseudomonas cellulosa hydrolyzes 4-O-methyl-D-glucuronoxylooligosaccharides but not 4-O-methyl-D-glucuronoxylan

J Bacteriol. 2002 Sep;184(17):4925-9. doi: 10.1128/JB.184.17.4925-4929.2002.

Abstract

The microbial degradation of xylan is a key biological process. Hardwood 4-O-methyl-D-glucuronoxylans are extensively decorated with 4-O-methyl-D-glucuronic acid, which is cleaved from the polysaccharides by alpha-glucuronidases. In this report we describe the primary structures of the alpha-glucuronidase from Cellvibrio mixtus (C. mixtus GlcA67A) and the alpha-glucuronidase from Pseudomonas cellulosa (P. cellulosa GlcA67A) and characterize P. cellulosa GlcA67A. The primary structures of C. mixtus GlcA67A and P. cellulosa GlcA67A, which are 76% identical, exhibit similarities with alpha-glucuronidases in glycoside hydrolase family 67. The membrane-associated pseudomonad alpha-glucuronidase released 4-O-methyl-D-glucuronic acid from 4-O-methyl-D-glucuronoxylooligosaccharides but not from 4-O-methyl-D-glucuronoxylan. We propose that the role of the glucuronidase, in combination with cell-associated xylanases, is to hydrolyze decorated xylooligosaccharides, generated by extracellular hemicellulases, to xylose and 4-O-methyl-D-glucuronic acid, enabling the pseudomonad to preferentially utilize the sugars derived from these polymers.

MeSH terms

  • Base Sequence
  • Cellvibrio / enzymology
  • Glycoside Hydrolases / analysis
  • Glycoside Hydrolases / genetics
  • Glycoside Hydrolases / physiology*
  • Hydrolysis
  • Membrane Proteins / physiology
  • Molecular Sequence Data
  • Oligosaccharides / metabolism*
  • Pseudomonas / enzymology*
  • RNA, Ribosomal, 16S / chemistry
  • Xylans / metabolism*

Substances

  • Membrane Proteins
  • Oligosaccharides
  • RNA, Ribosomal, 16S
  • Xylans
  • 4-O-methyl glucuronoxylan
  • Glycoside Hydrolases
  • alpha-glucuronidase

Associated data

  • GENBANK/AF448513
  • GENBANK/AF452103
  • GENBANK/AY065638
  • GENBANK/AY065639