Abstract
The nucleotide (nt) and deduced amino acid (aa) sequences are reported for the structural gene
cgkA
encoding K-carrageenase (M, 44 412) from the marine bacterium
Alteromonas carrageenovora (ATCC 43555), a hydrolase involved in the degradation of K-carrageenan. The
cgkA gene codes for a protein of 397 aa, with a signal peptide of 25 aa. The enzyme is a new member of family 16 of glycosyl hydrolases, which comprises β-1,3-1,4-glucanases from various sources and the β-agarase of
Streptomyces coelicolor. It is proposed that residue Glu
163 in the K-carrageenase from
A. carrageenovora and Glu
155 in the β-agarase from
S. coelicolor are important for catalysis.