Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedAlicyclobacillus acidocaldarius endoglucanase Cel9A (AaCel9A) is an inverting glycoside hydrolase with beta-1,4-glucanase activity on soluble polymeric substrates. Here, we report three X-ray structures of AaCel9A: a ligand-free structure at 1.8 A resolution and two complexes at 2.66 and 2.1 A resolution, respectively, with cellobiose obtained by co-crystallization and with cellotetraose obtained by the soaking method. AaCel9A forms an (alpha/alpha)(6)-barrel like other glycoside hydrolase family 9 enzymes. When cellobiose is used as a ligand, three glucosyl binding subsites are occupied, including two on the glycone side, while with cellotetraose as a ligand, five subsites, including four on the glycone side, are occupied. A structural comparison showed no conformational rearrangement of AaCel9A upon ligand binding. The structural analysis demonstrates that of the four minus subsites identified, subsites -1 and -2 show the strongest interaction with bound glucose. In conjunction with the open active-site cleft of AaCel9A, this is able to reconcile the previously observed cleavage of short-chain oligosaccharides with cellobiose as main product with the endo mode of action on larger polysaccharides. Crystal structures of A. acidocaldarius endoglucanase Cel9A in complex with cello-oligosaccharides: strong -1 and -2 subsites mimic cellobiohydrolase activity.,Eckert K, Vigouroux A, Lo Leggio L, Morera S J Mol Biol. 2009 Nov 20;394(1):61-70. Epub 2009 Aug 31. PMID:19729024[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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