title: A glycosyl hydrolase family 16 gene is responsible for the endogenous production of β-1,3-glucanases within decapod crustaceans.
abstract: To identify the gene responsible for the production of a β-1,3-glucanase (laminarinase) within crustacea, a glycosyl hydrolase family 16 (GHF16) gene was sequenced from the midgut glands of the gecarcinid land crab, Gecarcoidea natalis and the freshwater crayfish, Cherax destructor. An open reading frame of 1098 bp for G. natalis and 1095 bp for C. destructor was sequenced from cDNA. For G. natalis and C. destructor respectively, this encoded putative proteins of 365 and 364 amino acids with molecular masses of 41.4 and 41.5 kDa. mRNA for an identical GHF16 protein was also expressed in the haemolymph of C. destructor. These putative proteins contained binding and catalytic domains that are characteristic of a β-1,3-glucanase from glycosyl hydrolase family 16. The amino acid sequences of two short 8-9 amino acid residue peptides from a previously purified β-1,3-glucanase from G. natalis matched exactly that of the putative protein sequence. This plus the molecular masses of the putative proteins matching that of the purified proteins strongly suggests that the sequences obtained encode for a catalytically active β-1,3-glucanase. A glycosyl hydrolase family 16 cDNA was also partially sequenced from the midgut glands of other amphibious (Mictyris platycheles and Paragrapsus laevis) and terrestrial decapod species (Coenobita rugosus, Coenobita perlatus, Coenobita brevimanus and Birgus latro) to confirm that the gene is widely expressed within this group. There are three possible hypothesised functions and thus evolutionary routes for the β-1,3-glucanase: 1) a digestive enzyme which hydrolyses β-1,3-glucans, 2) an enzyme which cleaves β-1,3-glycosidic bonds within cell walls to release cell contents or 3) an immune protein which can hydrolyse the cell walls of potentially pathogenic micro-organisms.
authors.affiliation: School of Life and Environmental Sciences, Deakin University, 75 Pigdons Road, Waurn Ponds, Victoria 3216, Australia. Electronic address: stuart.linton@deakin.edu.au.
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Linton
authors.affiliation: School of Life and Environmental Sciences, Deakin University, 75 Pigdons Road, Waurn Ponds, Victoria 3216, Australia.
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Cameron
authors.affiliation: School of Life and Environmental Sciences, Deakin University, 75 Pigdons Road, Waurn Ponds, Victoria 3216, Australia.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Gray
authors.affiliation: School of Life and Environmental Sciences, Deakin University, 75 Pigdons Road, Waurn Ponds, Victoria 3216, Australia.
authors.forename: John A
authors.initials: JA
authors.lastname: Donald
authors.affiliation: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Saborowski
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: von Bergen
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Janina M
authors.initials: JM
authors.lastname: Tomm
authors.affiliation: Institute for Frontier Materials, Deakin University, 75 Pigdons Road, Waurn Ponds, Victoria, 3216, Australia.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Allardyce
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D044602:Cellulases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D033364:Decapoda / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D006434:Hemocytes / Q000201:enzymology / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D044602:Cellulases
keywords: Cherax destructor; Gecarcoidea natalis; Hemicellulase; Laminarinase; Land crab; β-1,3-glucanase