A new cold-adapted serine peptidase from Antarctic Lysobacter sp. A03: Insights about enzyme activity at low temperatures

- A cold-adapted proteinase from Lysobacter sp. was identified by screening a genomic library.
- The heterologous expression of the proteinase was carried out in E. coli cells.
- The enzyme was characterized is a serine peptidase with 35 kDa.
- Structural modelling predicted a less deep and more open binding pocket for this enzyme.

Currently, there is a great interest for customized biocatalysts that can supply the ongoing demand of industrial processes, but also deal with the growing concern about the environment. In this scenario, cold-adapted enzymes have features that make them very attractive for industrial and biotechnological purposes. Here, we describe A03Pep1, a new cold-adapted serine peptidase isolated from Lysobacter sp. A03 by screening a genomic library. The enzyme is synthesized as a large inactive prepropeptidase that, after intramolecular processing, gives rise to the active form, of 35 kDa. The heterologous expression of A03Pep1 was carried out in E. coli cells harboring the vector pGEX-4T-2-a0301. Its activity was optimal at pH 9.0 and 40 °C, in the presence of 25 mM Ca2+, which may contribute to the thermal stability of the enzyme. The 3D structure modelling predicted a less deep and more open binding pocket in A03Pep1 than that observed in the crystal structure of its mesophilic homologous AprV2, presumably as a way to enhance the probability of substrate binding at low temperatures. These results provide possible approaches in developing new biotechnologically relevant peptidases active at low to moderate temperatures.

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