{PDOC52006}
{PS52006; GH64}
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* Glycosyl hydrolases family 64 (GH64) domain profile *
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The glycoside hydrolases (GHs, EC 3.2.1.-) are a diverse set of enzymes with a
vast range of substrate specificity. GHs hydrolyze the glycosidic bond between
two or  more  carbohydrates  or  between  a  carbohydrate and non-carbohydrate
moiety. These  enzymes  play diverse roles in nature; they breakdown cellulose
into smaller  carbohydrates  (i.e.  during biomass degradation by cellulases),
they function  during  pathogenesis  such  as  the activity of influenza virus
neuraminidase, and  they  are  engaged  in normal cellular metabolic processes
that involve  the  formation  and  breakage  of  glycosidic  bonds  along with
glycosyl transferase.   All   reported   GH   family  64  (GH64)  members  are
laminaripentaose-producing "inverting" beta-1,3-glucanases [E1]. These enzymes
cleave the  beta-1,3-bonds  found  in  a  variety  of beta-1,3-glucans such as
laminarin or  pachyman.  "Inverting"  enzymes  utilize  a  single-displacement
reaction where  an  activated water molecule performs a nucleophilic attack at
the sugar  C-1 while concomitant aglycone departure is achieved by protonation
of the glycosidic oxygen [1,2,3,4].

The GH64  domain  is  composed  of  a barrel subdomain comprising mainly beta-
strands and  a  mixed  (alpha/beta)  subdomain  comprising  helices  and beta-
strands (see  <PDB:3GD0>).  It  takes the form of a crescent, with a wide-open
groove present  for  ligand  binding.  This wide groove is located between the
beta-barrel subdomain  and  the  mixed  alpha/beta-subdomain  and  the ligand-
binding cleft  in  it  is  lined  by negatively charged residues. Two strictly
conserved catalytic  residues, a Glu and an Asp, lie one-third of the way down
the groove  and  act  as  an  acid  catalyst and a base catalyst, respectively
[2,4].

Some proteins known to contain a GH64 domain are listed below:

 - Streptomyces  matensis  laminaripentaose  hydrolase  (SmLPHase),  cleaves a
   long-chain polysaccharide,  beta-1,3-glucan,  including  laminarin,  into a
   specific pentasaccharide oligomer "laminaripentaose" [1,2].
 - Paenibacillus  barengoltzii  GH  family 64 beta-1,3-glucanase (PbBgl64A), a
   multi-domain protein  that  belongs  to  the  GH64-TLP  superfamily,  which
   consists of an N-terminal CBM56 domain and a C-terminal family 64 GH domain
   [3].
 - Clostridium  beijerinckii  glucanallin,  composed of a BetaGamma-crystallin
   domain (see <PDOC00197>), a GH64 domain, and a CBM56 domain [4].

The profile we developed covers the whole GH64 domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: September 2022 / First entry.

[ 1] Nishimura T., Bignon C., Allouch J., Czjzek M., Darbon H.,
     Watanabe T., Henrissat B.
     "Streptomyces matensis laminaripentaose hydrolase is an 'inverting'
     beta-1,3-glucanase."
     FEBS. Lett. 499:187-190(2001).
     PubMed=11418137; DOI=10.1016/s0014-5793(01)02551-0
[ 2] Wu H.-M., Liu S.-W., Hsu M.-T., Hung C.-L., Lai C.-C., Cheng W.-C.,
     Wang H.-J., Li Y.-K., Wang W.-C.
     "Structure, mechanistic action, and essential residues of a GH-64
     enzyme, laminaripentaose-producing beta-1,3-glucanase."
     J. Biol. Chem. 284:26708-26715(2009).
     PubMed=19640850; DOI=10.1074/jbc.M109.010983
[ 3] Qin Z., Yang D., You X., Liu Y., Hu S., Yan Q., Yang S., Jiang Z.
     "The recognition mechanism of triple-helical beta-1,3-glucan by a
     beta-1,3-glucanase."
     Chem. Commun. (Camb). 53:9368-9371(2017).
     PubMed=28787048; DOI=10.1039/c7cc03330c
[ 4] Krishnan B., Srivastava S.S., Sankeshi V., Garg R., Srivastava S.,
     Sankaranarayanan R., Sharma Y.
     "betagamma-Crystallination Endows a Novel Bacterial Glycoside
     Hydrolase 64 with Ca(2+)-Dependent Activity Modulation."
     J. Bacteriol. 201:0-0(2019).
     PubMed=31527113; DOI=10.1128/JB.00392-19
[E1] http://www.cazy.org/GH64.html

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