Crystal structure of a ß-aminopeptidase from an Australian Burkholderia sp.

ABSTRACT

ß-Aminopeptidases are a unique group of enzymes that have the unusual capability to hydrolyze N-terminal ß-amino acids from synthetic ß-peptides. ß-Peptides can form secondary structures mimicking α-peptide-like structures that are resistant to degradation by most known proteases and peptidases. These characteristics of ß-peptides give them great potential as peptidomimetics. Here, the X-ray crystal structure of BcA5-BapA, a ß-aminopeptidase from a Gram-negative Burkholderia sp. that was isolated from activated sludge from a wastewater-treatment plant in Australia, is reported. The crystal structure of BcA5-BapA was determined to a resolution of 2.0 Šand showed a tetrameric assembly typical of the ß-aminopeptidases. Each monomer consists of an α-subunit (residues 1-238) and a ß-subunit (residues 239-367). Comparison of the structure of BcA5-BapA with those of other known ß-aminopeptidases shows a highly conserved structure and suggests a similar proteolytic mechanism of action.