Molecular cloning, DNA sequence, and expression of the gene encoding for thermostable pectate lyase of thermophilic...

The gene that encodes a thermostable pectate lyase (called PL 47), from Bacillus sp. TS 47, was cloned, sequenced, and expressed in mesophilic B. subtilis. The gene contained an open reading frame consisting of 1326 bp, which encoded 441 amino acids. The deduced amino acid sequence of the mature enzyme (416 amino acids with a calculated molecular mass of 47,262 Da), showed 52% similarity with PL (BsPel) from mesophilic B. subtilis SO113. The structure-based alignment of the deduced amino acid sequence of PL 47 with that of BsPel suggested that PL 47 might have a parallel beta-helix structure with three long loops. The amino acids making up PL 47 are richer in hydrophobic amino acids and glutamic acid than BsPel. The hydropathy profile of PL 47 indicated that the amino acid sequences around putative calcium binding sites are more hydrophobic than the same region of BsPel. The gene product expressed in B. subtilis as the host was stable up to 70 degrees C and the reaction was optimal around 70 degrees C, as well as native PL 47.