Comparative analysis of the recombinant α-glucosidases from the Thermotoga neapolitana and Thermotoga maritima maltodextrin utilization gene clusters

B. Veith, V. V. Zverlov, N. A. Lunina, O. V. Berezina, C. Raasch, G. A. Velikodvorskaya, W. Liebl

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3 Scopus citations

Abstract

The hyperthermophilic bacterium Thermotoga maritima contains an amylolytic gene cluster with two adjacent α-glucosidase genes, aglB and aglA. We have now identified a similar pair of α-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 α-glucosidases. AglB, in contrast to the cofactor-dependent (NAD+, Mn2+) α-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 α-glucosidase genes in the same amylolytic gene cluster of Thermotoga species are discussed.

Original languageEnglish
Pages (from-to)147-158
Number of pages12
JournalBiocatalysis and Biotransformation
Volume21
Issue number4-5
DOIs
StatePublished - 2003
Externally publishedYes

Keywords

  • AglA
  • AglB
  • Cyclomaltodextrinase
  • Hyperthermophile
  • Ther motoga
  • α-Glucosidase

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