An enzyme family reunion — similarities, differences and eccentricities in actions on α-glucans

Abstract

α-Glucans in general, including starch, glycogen and their derived oligosaccharides are processed by a host of more or less closely related enzymes that represent wide diversity in structure, mechanism, specificity and biological role. Sophisticated three-dimensional structures continue to emerge hand-in-hand with the gaining of novel insight in modes of action. We are witnessing the "test of time" blending with remaining questions and new relationships for these enzymes. Information from both within and outside of ALAMY 3 Symposium will provide examples on what the family contains and outline some future directions. In 2007 a quantum leap crowned the structural biology by the glucansucrase crystal structure. This initiates the disclosure of the mystery on the organisation of the multidomain structure and the "robotics mechanism" of this group of enzymes. The central issue on architecture and domain interplay in multidomain enzymes is also relevant in connection with the recent focus on carbohydrate-binding domains as well as on surface binding sites and their long underrated potential. Other questions include, how different or similar are glycoside hydrolase families 13 and 31 and is the lid finally lifted off the disguise of the starch lyase, also belonging to family 31? Is family 57 holding back secret specificities? Will the different families be sporting new "eccentric" functions, are there new families out there, and why are crystal structures of "simple" enzymes still missing? Indeed new understanding and discovery of biological roles continuously emphasize value of the collections of enzyme models, sequences, and evolutionary trees which will also be enabling advancement in design for useful and novel applications.

The Importance of Surface-Binding Site towards Starch-Adsorptivity Level in α-Amylase: A Review on Structural Point of View

“…Moreover, another preliminary work indicated that the starch binding to SBS2 in AMY2 is weaker than in AMY1. This finding was also confirmed by its crystal structure [ 32 ].…”

Domain evolution in the GH13 pullulanase subfamily with focus on the carbohydrate-binding module family 48

“…Despite an extremely large number of available sequences (more than 4,500 CAZy entries) and almost 30 different enzyme specificities, the α-amylase family members possess several typical common features. These are (Svensson 1994;Kuriki & Imanaka 1999;MacGregor et al 2001;Janecek 1997Janecek , 2002avan der Maarel et al 2002;MacGregor 2005;Kuriki et al 2006;Seo et al 2008): (i) acting on α-glucosidic linkages, i.e. their hydrolysis or formation by transglycosylation; (ii) possessing from 4 up to 7 conserved sequence regions; (iii) adopting the parallel (β/α) 8 -barrel domain (i.e.…”

Lignocellulolytic Potential of Microbial Consortia Isolated from a Local Biogas Plant: The Case of Thermostable Xylanases Secreted by Mesophilic Bacteria

“…Within GHs, the most abundant family across all nine microbiomes were GH13 (517 ORFs), of which 171 and 125 ORFs were found in T 9 -37 (in red) and T 9 -50 (in green), respectively (Figure 10 and Table 4). This family, together with GH4, GH31, GH57, GH63, GH97, and GH126, can be linked to starch degradation by encompassing starch-and pullulanmodifying enzymes, including α-amylases, pullulanases, α-1,6-glucosidases, neopullulanases, and cyclodextrinases [38]. From a biotechnological point of view, amylases are among the most important enzymes for the food industry and recently have found applications also in biofilm inhibition [39].…”