Structural highlights
Function
AGAA_ZOBGA Cleaves the beta-1,4-linkages between beta-D-galactose and alpha-L-3,6-anhydro-galactose residues in agarose. Cleaves agarose in a random manner with retention of the anomeric-bond configuration, producing beta-anomers that give rise progressively to alpha-anomers when mutarotation takes place.[1]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Agarose is a gel-forming polysaccharide with an alpha-L(1,4)-3,6-anhydro-galactose, beta-D(1,3)-galactose repeat unit, from the cell walls of marine red algae. beta-agarase A, from the Gram-negative bacterium Zobellia galactanivorans, is secreted to the external medium and degrades agarose with an endo-mechanism. The structure of the inactive mutant beta-agarase A-E147S in complex with agaro-octaose has been solved at 1.7 A resolution. Two oligosaccharide chains are bound to the protein. The first one resides in the active site channel, spanning subsites -4 to -1. A second oligosaccharide binding site, on the opposite side of the protein, was filled with eight sugar units, parallel to the active site. The crystal structure of the beta-agarase A with agaro-octaose provides detailed information on agarose recognition in the catalytic site. The presence of the second, parallel, binding site suggests that the enzyme might be able to unwind the double-helical structure of agarose prior to the catalytic cleavage.
Parallel substrate binding sites in a beta-agarase suggest a novel mode of action on double-helical agarose.,Allouch J, Helbert W, Henrissat B, Czjzek M Structure. 2004 Apr;12(4):623-32. PMID:15062085[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Jam M, Flament D, Allouch J, Potin P, Thion L, Kloareg B, Czjzek M, Helbert W, Michel G, Barbeyron T. The endo-beta-agarases AgaA and AgaB from the marine bacterium Zobellia galactanivorans: two paralogue enzymes with different molecular organizations and catalytic behaviours. Biochem J. 2005 Feb 1;385(Pt 3):703-13. PMID:15456406 doi:http://dx.doi.org/10.1042/BJ20041044
- ↑ Allouch J, Helbert W, Henrissat B, Czjzek M. Parallel substrate binding sites in a beta-agarase suggest a novel mode of action on double-helical agarose. Structure. 2004 Apr;12(4):623-32. PMID:15062085 doi:10.1016/j.str.2004.02.020
