Enzymatic properties of the highly thermophilic and alkaline pectate lyase Pel-4B from alkaliphilic Bacillus sp. strain P-4-N and the entire nucleotide and amino acid sequences.

We cloned two genes for alkaline pectate lyase, pel-4A and pel-4B, from alkaline pectinase-producing alkaliphilic Bacillus sp. strain P-4-N. The pel-4B gene product Pel-4B was purified to homogeneity and characterized. The purified enzyme had an isoelectric point of pH 9.6 and a molecular mass of 35 kDa, values close to those of the pel-4A gene product Pel-4A. The pH and temperature optima for activity were as high as 11.5 and 70 degrees C, respectively, which are the highest among the pectate lyases reported to date. The mature Pel-4B (304 amino acids; 33,868 Da) was structurally related to the enzymes in the polysaccharide lyase family 1 and showed 35.6% identity with Pel-4A on the amino acid level. It showed significant homology to other pectate lyases in the same family, such as the enzymes from alkaliphilic Bacillus sp. strains KSM-P7 and KSM-P103 and the fungi Aspergillus nidulans and Colletotrichum gloeosporioides f. sp. malvae.