PROSITE documentation PDOC00794
Glycosyl hydrolases family 16 (GH16) signature and domain profile


The glycosyl hydrolases family 16 (GH16) [1,E1] contains functionally heterogeneous members, including β-agarases, endo-1,3-β-glucanases (laminarinases), endo-β-1,3-1,4-glucanases (lichenases), kappa-carrageenases, endo-β-galactosidases and xyloglucan endotransferases. These enzymes share a common ancestor and have diverged significantly in their primary sequence.

The GH16 catalytic domain has a classical sandwich-like β-jelly roll fold, formed by two main, closely packed and curved antiparallel β sheets, creating a deep channel harboring the catalytic machinery (see <PDB:1DYP>). Even though the GH16 domains have now diverged significantly in their primary sequences, they all feature a common catalytic motif, E-[ILV]-D-[IVAF]-[VILMF](0,1)-E. The two glutamic acid residues in the conserved motif are the nucleophile and the general base involved in catalysis, whereas the aspartic acid residue is important in maintaining the relative position of these catalytic amino acids [2,3].

Some proteins known to contain a GH16 domain are listed below:

  • Bacterial β-1,3-1,4-glucanases, or lichenases, (EC mainly from Bacillus but also from Clostridium thermocellum (gene licB), Fibrobacter succinogenes and Rhodothermus marinus (gene bglA).
  • Bacillus circulans β-1,3-glucanase A1 (EC (gene glcA).
  • Alteromonas carrageenovora kappa-carrageenase (EC (gene cgkA).
  • Rhizobium meliloti endo-1,3-1,4-β-glycanase exoK.
  • Streptomyces coelicolor agarase (EC (gene dagA).
  • Zobellia galactanivorans β-agarase A (EC (gene agaA).
  • Zobellia galactanivorans β-agarase B (EC (gene agaB).
  • Saccharophagus sp. AG21 β-agarase (gene agy1), includes a GH16 domain and two CBM6 (carbohydrate binding type-6) domain (see <PDOC51175>).
  • Microbulbifer thermotolerans agarase (agaA).
  • Thermotoga maritima laminarinase.
  • Saccharomyces cerevisiae β-glucan synthesis-associated protein SKN1 [5].
  • Saccharomyces cerevisiae β-glucan synthesis-associated protein KRE6 [5].

Two closely clustered conserved glutamates have been shown [6] to be involved in the catalytic activity of Bacillus licheniformis lichenase. We used the region that contains these residues as a signature pattern. We have also developed a profile that covers the entire GH16 domain.

Expert(s) to contact by email:

Henrissat B.

Last update:

June 2015 / Text revised; profile added.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

GH16_2, PS51762; Glycosyl hydrolases family 16 (GH16) domain profile  (MATRIX)

GH16_1, PS01034; Glycosyl hydrolases family 16 active sites  (PATTERN)


1AuthorsHenrissat B.
TitleA classification of glycosyl hydrolases based on amino acid sequence similarities.
SourceBiochem. J. 280:309-316(1991).
PubMed ID1747104

2AuthorsAllouch J. Jam M. Helbert W. Barbeyron T. Kloareg B. Henrissat B. Czjzek M.
TitleThe three-dimensional structures of two beta-agarases.
SourceJ. Biol. Chem. 278:47171-47180(2003).
PubMed ID12970344

3AuthorsMichel G. Chantalat L. Duee E. Barbeyron T. Henrissat B. Kloareg B. Dideberg O.
TitleThe kappa-carrageenase of P. carrageenovora features a tunnel-shaped active site: a novel insight in the evolution of Clan-B glycoside hydrolases.
SourceStructure 9:513-525(2001).
PubMed ID11435116

4AuthorsThevissen K. Idkowiak-Baldys J. Im Y.-J. Takemoto J. Francois I.E.J.A. Ferket K.K.A. Aerts A.M. Meert E.M.K. Winderickx J. Roosen J. Cammue B.P.A.
TitleSKN1, a novel plant defensin-sensitivity gene in Saccharomyces cerevisiae, is implicated in sphingolipid biosynthesis.
SourceFEBS Lett. 579:1973-1977(2005).
PubMed ID15792805

5AuthorsMontijn R.C. Vink E. Mueller W.H. Verkleij A.J. Van Den Ende H. Henrissat B. Klis F.M.
TitleLocalization of synthesis of beta1,6-glucan in Saccharomyces cerevisiae.
SourceJ. Bacteriol. 181:7414-7420(1999).
PubMed ID10601196

6AuthorsJuncosa M. Pons J. Dot T. Querol E. Planas A.
TitleIdentification of active site carboxylic residues in Bacillus licheniformis 1,3-1,4-beta-D-glucan 4-glucanohydrolase by site-directed mutagenesis.
SourceJ. Biol. Chem. 269:14530-14535(1994).
PubMed ID8182059


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