title: Genetic and biochemical characterization of the Pseudoalteromonas tetraodonis alkaline κ-carrageenase.
abstract: An alkaline κ-carrageenase, Cgk-K142, was found in the culture broth of a deep-sea bacterium, Pseudoalteromonas tetraodonis JAM-K142. A gene for the enzyme was cloned and expressed. Purified recombinant Cgk-K142 (rCgk-K142) showed an optimal pH of about 8.8 in glycine-NaOH buffer at 30 °C and of about 8.0 in MOPS buffer at 50 °C. The optimal temperature for the enzyme was 55 °C at pH 8.0. rCgk-K142 was unstable, but λ- and ι-carrageenans, non-degradative substrate homologs, extensively enhanced its stability. The nucleotide sequence of the gene for Cgk-K142 comprised 1,194 bp, and the deduced amino acid sequence (397 amino acids) showed a high level of similarity to the κ-carrageenase of P. carrageenovora, with 94% identity. Another gene for a κ-carrageenase-like protein was found downstream of the gene for Cgk-K142. The nucleotide sequence of that gene consisted of 966 bp (321 amino acids), and it showed the highest similarity, at 64% identity, to protein CgkB of P. carrageenovora, which has been reported as an incomplete 57-amino acid sequence.
authors.affiliation: Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan. kobayashit@jamstec.go.jp
authors.forename: Tohru
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Uchimura
authors.forename: Osamu
authors.initials: O
authors.lastname: Koide
authors.forename: Shigeru
authors.initials: S
authors.lastname: Deguchi
authors.forename: Koki
authors.initials: K
authors.lastname: Horikoshi
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D031161:Pseudoalteromonas / Q000201:enzymology / Q000235:genetics*; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017423:Sequence Analysis, RNA; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D006026:Glycoside Hydrolases