Escherichia coli encodes two aminopeptidases belonging to the M17 family: Peptidase A (PepA) and Peptidase B (PepB). To gain insights into their substrate specificities, PepA or PepB were overexpressed in δpepN, which shows greatly reduced activity against the majority of amino acid substrates. Overexpression of PepA or PepB increases catalytic activity of several aminopeptidase substrates and partially rescues growth of δpepN during nutritional downshift and high temperature stress. Purified PepA and PepB display broad substrate specificity and Leu, Lys, Met and Gly are preferred substrates. However, distinct differences are observed between these two paralogs: PepA is more stable at high temperature whereas PepB displays broader substrate specificity as it cleaves Asp and insulin B chain peptide. Importantly, this strategy, i.e. overexpression of peptidases in δpepN and screening a panel of substrates for cleavage, can be used to rapidly identify peptidases with novel substrate specificities encoded in genomes of different organisms.
|Number of pages||6|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - 01-01-2010|
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology