Veith B, Zverlov VV, Lunina NA, Berezina OV, Raasch C, Velikodvorskaya GA, Liebl W
BIOCATALYSIS AND BIOTRANSFORMATION
21 (4-5): 147-158 AUG 2003
Document type: Article
Language: English
Cited References: 59 Times
Abstract:
The hyperthermophilic bacterium Thermotoga maritima contains an amylolytic gene
cluster with two adjacent alpha-glucosidase genes, aglB and aglA . We have now
identified a similar pair of alpha-glucosidase genes on a 5,451 bp fragment
of T. neapolitana genomic DNA. Like in T. maritima , aglA of T. neapolitana
is located downstream of aglB . The deduced AglB primary structure allows its
assignment to glycoside hydrolase family 13 (GHF13), whereas AglA belongs to
GHF4. The aglB gene of T. neapolitana and the corresponding gene from T. maritima
were expressed in E. coli , and the recombinant enzymes were characterized.
Both enzymes hydrolyzed cyclomaltodextrins and linear maltooligosaccharides
to yield glucose and maltose. Evidence from the hydrolysis of non-natural oligosaccharides
and the pseudo-tetrasaccharide acarbose suggests that linear malto-oligosaccharides
are progressively degraded by T. neapolitana and T. maritima AglB from the reducing
end, which is highly uncommon for alpha-glucosidases. AglB, in contrast to the
cofactor-dependent (NAD(+) , Mn2+) alpha-glucosidase AglA, does not cleave maltose.
The recent elucidation of the crystal structure of T. maritima AglA indicates
that AglA and AglB employ different catalytic mechanisms for glycosidic bond
cleavage. Possible reasons for the presence of two alpha-glucosidase genes in
the same amylolytic gene cluster of Thermotoga species are discussed. Author
Keywords: alpha-glucosidase, cyclomaltodextrinase, AglA, AglB, hyperthermophile,
Thermotoga
KeyWords Plus: HYPERTHERMOPHILIC BACTERIUM, MALTOGENIC AMYLASE, ESCHERICHIA-COLI, CRYSTAL-STRUCTURE, THERMOACTINOMYCES-VULGARIS, MOLECULAR CHARACTERIZATION, SULFOLOBUS-SOLFATARICUS, BACILLUS-SPHAERICUS, CATALYTIC MECHANISM, FLAVOBACTERIUM SP
Publisher: TAYLOR & FRANCIS LTD,
4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND
IDS Number: 751BG
ISSN: 1024-2422