Amylolytic glycoside hydrolases
Cell. Mol. Life Sci.
Amylolytic glycoside hydrolases
Sˇ tefan Janecˇek 0 1 2 3
Birte Svensson 0 1 2 3
0 Department of Biology, Faculty of Natural Sciences, University of SS. Cyril and Methodius in Trnava , Na ́m. J. Herdu 2, 91701 Trnava , Slovakia
1 Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences , Du ́bravska ́ cesta 21, 84551 Bratislava , Slovakia
2 & Sˇ tefan Janecˇek
3 Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark , Elektrovej Building 375, 2800 Kongens Lyngby , Denmark
When in 1991 Bernard Henrissat created the sequencebased classification of glycoside hydrolases (GH) [1], it was not easy to imagine at that time how huge scope and impact the subsequently established new database of Carbohydrate-Active enZymes, CAZy [2], would have. The aamylase family (family GH13) with 40 sequences bearing 10 different enzyme specificities was already from the beginning a bit exceptional compared to, e.g., the other amylolytic enzyme families of b-amylase and glucoamylase each encompassing just 5 sequences and no other specificities [1]. Currently, a-amylase, as a proper enzyme is present in the main a-amylase family GH13 (forming with families GH70 and GH77 the clan GH-H), in families GH57 and GH119, and eventually in GH126 [3]. In addition to catalytic domains annotated to GH families, noncatalytic domains termed carbohydrate-binding modules
Amylolytic enzymes; CAZy database; Starch and glycogen metabolism; Structure and function of enzymes; Protein design and evolution
-
(CBM) facilitating enzyme binding to different saccharides
are also organised in sequence-based families as an integral
part of the CAZy classification system [
2
].
The actual size of the main a-amylase family GH13
with more than 31,500 members and 30 enzyme
specificities is really impressive [
2
]. The overall concept of the
a-amylase family as it is known and accepted today was,
however, based not only on GH classification, but resulted
from contribution of an enormous amount of both
experimental and theoretical studies. Among these pioneering
prediction in silico analyses delivered by Birte Svensson
and Ann MacGregor [
4–9
] have received special attention.
In this regard, also the discovery of neopullulanase by
Takashi Kuriki [
10, 11
], as a universal enzyme capable to
catalyse all four main reactions characteristic for the
family, i.e., hydrolysis and formation by transglycosylation
of both a-1,4- and a-1,6-glycosidic linkages [
12
], deserves
to be mentioned.
The present multi-author review issue was collected in
an effort to illustrate and map the universe of amylolytic
hydrolases and additional a-glucan modifying enzymes
with emphasis on retaining enzymes as well as other
enzymes involved in starch biosynthesis, metabolism and
oxidative degradation. The entire collection of eleven
review articles starts with the story by the team led by
Nicole Koropatkin on the Sus operon that constitutes the
starch utilisation system in mammalian gut bacteria from
the order Bacteroidetes and encodes eight unique proteins
responsible for both binding and degradation of starch at
the cell surface. The next two reviews written by the group
of Birte Svensson and Eiji Suzuki and his co-author are
devoted to structure/function and evolution of debranching
and branching enzymes, respectively, from families GH13
and GH57 elucidating their nuances not only with regard to
primary and tertiary structures but also within taxonomy.
Two further reviews prepared by the groups of Magali
Remaud-Simeon and Lubbert Dijkhuizen focus on the
family GH70 glucansucrases presenting circularly
permuted versions of the characteristic family GH13, the
former article in addition pays attention to the
biotechnologically important GH13 amylosucrase, while the latter
highlights the very recent observation of non-permuted
glucansucrases interestingly kept classified in family
GH70. In the subsequent review, Stefan Janecek and his
co-author offer details on three remarkable evolutionary
stories concerning relatedness of plant and archaeal
aamylases, animal proteins rBAT and 4F2 and microbial
aglucosidases—both from the family GH13 as well as the
amylomaltases from borreliae of family GH77. The next
article delivered by the team headed by Haruhide Mori and
Atsuo Kimura illustrates diverse functions of
a-glucosidases from the main a-amylase family GH13 compared to
those from the related GH31 family that also includes
a1,4-glucan lyases producing anhydrofructose as opposed to
the a-glucosidases which release a-glucose.
The issue continues with the review written by the group
of Joerg Fettke with focus on phosphorylation of glucosyl
residues of starch during its metabolism mainly within
green algae and land plants, which is mediated by two
special enzymes called the glucan, water dikinase and the
phosphoglucan, water dikinase containing also
starchbinding domains of families CBM20 a (...truncated)