Uml2 is a novel CalB-type lipase of Ustilago maydis with phospholipase A activity

Appl Microbiol Biotechnol. 2014 Jun;98(11):4963-73. doi: 10.1007/s00253-013-5493-6. Epub 2014 Jan 28.

Abstract

CalB of Pseudozyma aphidis (formerly named Candida antarctica) is one of the most widely applied enzymes in industrial biocatalysis. Here, we describe a protein with 66 % sequence identity to CalB, designated Ustilago maydis lipase 2 (Uml2), which was identified as the product of gene um01422 of the corn smut fungus U. maydis. Sequence analysis of Uml2 revealed the presence of a typical lipase catalytic triad, Ser-His-Asp with Ser125 located in a Thr-Xaa-Ser-Xaa-Gly pentapeptide. Deletion of the uml2 gene in U. maydis diminished the ability of cells to hydrolyse fatty acids from tributyrin or Tween 20/80 substrates, thus demonstrating that Uml2 functions as a lipase that may contribute to nutrition of this fungal pathogen. Uml2 was heterologously produced in Pichia pastoris and recombinant N-glycosylated Uml2 protein was purified from the culture medium. Purified Uml2 released short- and long-chain fatty acids from p-nitrophenyl esters and Tween 20/80 substrates. Furthermore, phosphatidylcholine substrates containing long-chain saturated or unsaturated fatty acids were effectively hydrolysed. Both esterase and phospholipase A activity of Uml2 depended on the Ser125 catalytic residue. These results indicate that Uml2, in contrast to CalB, exhibits not only esterase and lipase activity but also phospholipase A activity. Thus, by genome mining, we identified a novel CalB-like lipase with different substrate specificities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Catalytic Domain
  • Cloning, Molecular
  • DNA Mutational Analysis
  • Gene Deletion
  • Gene Expression
  • Phospholipases / genetics
  • Phospholipases / metabolism*
  • Pichia / genetics
  • Pichia / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sequence Analysis, DNA
  • Substrate Specificity
  • Ustilago / enzymology*
  • Ustilago / genetics

Substances

  • Recombinant Proteins
  • Phospholipases