|
|
International Summer School
From Genome to Life:
Structural, Functional and Evolutionary approaches
|
NAUMOFF
Daniil |
|
State Institute For Genetics And Selection of Industrial Microorganisms, Laboratory Of Bioinformatics, I-Dorozhny Proezd, 1, Moscow 113545, Russia title: Sequence analysis and classification of alpha-galactosidases Glycosyl
hydrolases are a widespread group of enzymes that
hydrolyze the glycosidic bonds between two
carbohydrate residues. Currently, several thousand
sequences of the proteins are known. They are
grouped into 83 families on the basis of sequence
similarity (http://afmb.cnrs-mrs.fr/CAZY/). Four of
these families (GH4, GH27, GH36, and GH57) include
enzymes with alpha-galactosidase activity [E.C.
3.2.1.22]. GH4 and GH57 families encompass
several types of glycosyl hydrolases. The
alpha-galactosidase activity has been demonstrated
only for three enzymes of GH4 family (from
Escherichia coli, Thermotoga maritima, and T.
neapolitana) and two enzymes of GH57 family (from
Pyrococcus furiosus and Thermococcus alcaliphilus).
The majority of known alpha-galactosidases belong
to GH27 and GH36 families, which compose a
superfamily (clan GH-D). We have performed sequence
analysis of the two families. Most of GH27
sequences have a high level of sequence similarity
(more than 30% of identical residues) and make up a
distinct subfamily. Four main subgroups can be
distinguished in this subfamily (> 50% of
identical residues). One of them includes plant and
Clostridium josui alpha-galactosidases and a
hypothetical protein (ORF) from Streptomyces
coelicolor. Other two subgroups comprise
glycosidases from Ascomycota yeast and Vertebrata
respectively. Some fungal alpha-galactosidases form
the fourth subgroup. One of the Trichoderma reesei
aipha-galactosidases, Arthrobacter globiformis
isomaltodextranase, and Bacillus halodurans
hypothetical protein along with two Arabidopsis
thaliana hypothetical proteins are the most
divergent representatives of GH27 family and can be
considered the only known representatives of three
other subfamilies. GH36 family is composed of two
main subfamilies. Subfamily 36a includes
alpha-galactosidases from Gram-positive bacteria,
Absidia corymbifera, Aspergillus niger, Escherichia
coli, and Trichoderma reesei as well as a
hypothetical protein from Yersinia pestis.
Subfamily 36b contains enzymes from Gram-negative
bacteria (Proteobacteria, Thermotogales, and
Thermus) and one hypothetical protein from
Streptomyces coelicolor. Another hypothetical
protein from St. coelicolor can be thought of as
the only representative of the third subfamily. We
will present data about homology of
alpha-galactosidases from GH27 and GH36 families
with glycosidases of GH31 family and proteins of
aGalT family. The aGalT family is comprised of
alpha-galactosyltransferases and seed imbibition
proteins from higher plants, Bifidobacterium breve
alpha-galactosidase, and hypothetical proteins from
Sulfolobus solfataricus and Sul. tokodaii. We
propose to include GH31 and aGalT families into the
alpha-galactosidase superfamily, in addition to
GH27 and GH36 families. |
|
ADDITIONAL DATA |
|
|