A novel multifunctional α-amylase from the thermophilic fungus Malbranchea cinnamomea: biochemical characterization and three-dimensional structure

Appl Biochem Biotechnol. 2013 May;170(2):420-35. doi: 10.1007/s12010-013-0198-y. Epub 2013 Mar 29.

Abstract

A novel α-amylase (McAmyA) from the thermophilic fungus, Malbranchea cinnamomea was purified, characterized and crystallized in the present study. McAmyA was purified to apparent homogeneity with a molecular mass of 60.3 kDa on SDS-PAGE. The enzyme exhibited maximal activity at pH 6.5 and was stable within pH 5.0-10.0. It was most active at 65 °C and was stable up to 50 °C. McAmyA was capable of hydrolyzing amylose, starch, amylopectin, pullulan, cyclodextrins and maltooligosaccharides. The full-length cDNA of an α-amylase gene (McAmyA) from the strain was cloned. McAmyA consisted of a 1,476-bp open reading frame encoding 492 amino acids. It displayed the highest amino acid sequence homology (less than 60 %) with the reported α-amylases. The crystal structure of McAmyA was solved at a resolution of 2.25 Å (PDB code 3VM7). The overall structure of McAmyA reveals three domains with ten α helices and 14 β strands, and the putative catalytic residues are positioned at domain A with somewhat different secondary structural circumstances compared with typical α-amylases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amylopectin / chemistry
  • Amylose / chemistry
  • Ascomycota / enzymology*
  • Ascomycota / genetics
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • DNA, Fungal / genetics
  • Enzyme Activation
  • Enzyme Stability
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification*
  • Hot Temperature
  • Hydrogen-Ion Concentration
  • Hydrolysis
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid
  • Species Specificity
  • Substrate Specificity
  • alpha-Amylases / chemistry
  • alpha-Amylases / genetics
  • alpha-Amylases / isolation & purification*

Substances

  • DNA, Complementary
  • DNA, Fungal
  • Fungal Proteins
  • Amylose
  • Amylopectin
  • alpha-Amylases