Characterization of a glycoside hydrolase family 1 β-galactosidase from hot spring metagenome with transglycosylation activity

Appl Biochem Biotechnol. 2012 Nov;168(6):1681-93. doi: 10.1007/s12010-012-9889-z. Epub 2012 Sep 27.

Abstract

A novel, thermostable, alkalophilic β-D-galactosidase (Mbgl) was isolated from a metagenome of geothermal springs in northern Himalayan region of India. Mbgl was 447 amino acids in size and had conserved catalytic residues E170 and E358, indicating that it belonged to family 1 of glycosyl hydrolases showing maximum homology (89 %) with uncharacterized β-galactosidase of Eubacterium, Meiothermus ruber DSM1279. Temperature and pH optima of Mbgl were 65 °C and 8.0 respectively, and it retained 80 % activity even at pH 10.0. Mbgl was active as a homotetramer, recognized β-(1,4)-D-galactoside as the preferred glycosidic bond, and preferentially hydrolyzed pNPgal with K(m) 3.33 mM and k(cat) 2,000 s(-1). It displayed high transglycosylation activity with wide acceptor specificity including hexoses and pentoses leading to the formation of prebiotic galacto-oligosaccharides whereas its lactose hydrolysis potential was low.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacteria / classification
  • Bacteria / enzymology*
  • Bacteria / genetics
  • Bacteria / isolation & purification
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Enzyme Stability
  • Hot Springs / microbiology*
  • Kinetics
  • Metagenome*
  • Molecular Sequence Data
  • Sequence Alignment
  • beta-Galactosidase / chemistry*
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism

Substances

  • Bacterial Proteins
  • beta-Galactosidase

Associated data

  • GENBANK/JF950286