A novel low-temperature active alkaline pectate lyase from Klebsiella sp. Y1 with potential in textile industry

Alkaline pectate lyases are favorable for the textile industry. Here we report the cloning of a pectate lyase gene (pl A), from Klebsiella sp. Y1, and its heterologous expression in Escherichia coli. The full-length pl A consists of 1710 bp and encodes for a 569-amino acid polypeptide including a putative 22-residue signal peptide and a catalytic domain belonging to pectate lyase family 2. The recombinant enzyme (r-PL A) was purified to electrophoretic homogeneity by single-step Ni²⁺-NTA affinity chromatography and showed an apparent molecular weight of ∼60 kDa. The pH and temperature optima of r-PL A were found to be 9.0 and 30–50 °C, respectively. r-PL A was highly active at low temperatures, exhibiting >60% of the maximal activity at 20 °C and >20% activity even at 0 °C. The enzyme was stable in a broad alkaline pH range of 7.0–12.0 for 1 h at 37 °C. The values of K_m(app) and V_max(app) of r-PL A for polygalacturonic acid were 2.47 mg/ml and 11.94 μmol/min/mg, respectively. Compared with the commercial compound pectinase from Novozymes, purified r-PL A showed similar efficacy in reducing the intrinsic viscosity of polygalacturonic acid (68.8% vs. 67.1%) and in bioscouring of jute (7.38% vs. 7.58%). Thus r-PL A is a valuable material for the textile industry.