3GZK

Structure of A. Acidocaldarius Cellulase CelA

Summary for 3GZK

• Entry DOI: 10.2210/pdb3gzk/pdb
• Descriptor: Cellulase, CALCIUM ION, ZINC ION, ... (5 entities in total)
• Functional Keywords: fold from gh9 from cazy database, glycosidase, hydrolase
• Biological source: Alicyclobacillus acidocaldarius subsp. acidocaldarius (Bacillus acidocaldarius)
• Total number of polymer chains: 1
• Total formula weight: 59372.83

Authors

Morera, S.,Eckert, K.,Vigouroux, A. (deposition date: 2009-04-07, release date: 2009-10-13, Last modification date: 2023-11-01)

Primary citation

Eckert, K.,Vigouroux, A.,Lo Leggio, L.,Morera, S.
Crystal structures of A. acidocaldarius endoglucanase Cel9A in complex with cello-oligosaccharides: strong -1 and -2 subsites mimic cellobiohydrolase activity
J.Mol.Biol., 394:61-70, 2009

PubMed Abstract: Alicyclobacillus 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.

PubMed: 19729024
DOI: 10.1016/j.jmb.2009.08.060

Experimental method

X-RAY DIFFRACTION (1.8 Å)