Two novel cyclodextrin-degrading enzymes isolated from thermophilic bacteria have similar domain structures but differ in oligomeric state and activity profile

Pernilla Turner, Antje Labes, Olafur H Fridjonsson, Gudmundur O Hreggvidson, Peter Schönheit, Jakob K Kristjansson, Olle Holst, Eva Nordberg Karlsson

Research output: Contribution to journalArticlepeer-review

23 Citations (SciVal)

Abstract

In this paper, we present the expression and characterization of two novel enzymes from the a-amylase family exhibiting cyclomaltodextrinase specificity. The nucleotide sequences encoding the enzymes were isolated from the genomic DNA of two thermophilic bacterial strains originating from Icelandic hot springs and belonging to the genera Anoxybacillus (AfCda13) and Laceyella (LsCda13). The genes were amplified using a consensus primer strategy utilizing two of the four conserved regions present in glycoside hydrolase family 13. No identifiable signal peptides were present in open reading frames encoding the enzymes, indicating an intracellular location of both enzymes, and their physiological function to be intracellular cyclodextrin degradation. The domain structures of both enzymes were also similar, including an N-terminal domain, the catalytic module composed of the A- and B-domains, and a C-terminal domain. Despite the similarity in domain composition, the two enzymes displayed differences in the oligomeric state with AfCda13 being a dimeric protein, whereas LsCda13 was monomeric. The two enzymes also displayed significantly different activity profiles, despite being active on the same range of substrates. It was shown that the enzyme displaying the highest activity on cyclodextrin was dimeric (AfCda13). Moreover, a fraction of the dimeric enzyme could be converted to a monomeric state in the presence of KCl and this fraction retained only 23% of its activity on a-cyclodextrin while its activity on starch was not significantly affected, indicating that the oligomeric state is an important factor for a high activity on cyclodextrin substrates.
Original languageEnglish
Pages (from-to)380-390
JournalJournal of Bioscience and Bioengineering
Volume100
Issue number4
DOIs
Publication statusPublished - 2005

Subject classification (UKÄ)

  • Industrial Biotechnology

Keywords

  • cyclomaltodextrinase
  • glycoside hydrolase family 13
  • Anoxybacillus
  • Laceyella

Fingerprint

Dive into the research topics of 'Two novel cyclodextrin-degrading enzymes isolated from thermophilic bacteria have similar domain structures but differ in oligomeric state and activity profile'. Together they form a unique fingerprint.

Cite this