1G66

ACETYLXYLAN ESTERASE AT 0.90 ANGSTROM RESOLUTION

Summary for 1G66

• Entry DOI: 10.2210/pdb1g66/pdb
• Related: 1BS9 2AXE
• Descriptor: ACETYL XYLAN ESTERASE II, SULFATE ION, GLYCEROL, ... (4 entities in total)
• Functional Keywords: serine hydrolase, acetyl xylopyranose, xylan, hydrolase
• Biological source: Penicillium purpurogenum
• Cellular location: Secreted: O59893
• Total number of polymer chains: 1
• Total formula weight: 21414.43

Authors

Ghosh, D.,Sawicki, M.,Lala, P.,Erman, M.,Pangborn, W.,Eyzaguirre, J.,Gutierrez, R.,Jornvall, H.,Thiel, D.J. (deposition date: 2000-11-03, release date: 2001-01-17, Last modification date: 2024-12-25)

Primary citation

Ghosh, D.,Sawicki, M.,Lala, P.,Erman, M.,Pangborn, W.,Eyzaguirre, J.,Gutierrez, R.,Jornvall, H.,Thiel, D.J.
Multiple conformations of catalytic serine and histidine in acetylxylan esterase at 0.90 A.
J.Biol.Chem., 276:11159-11166, 2001

PubMed Abstract: Acetylxylan esterase (AXEII; 207 amino acids) from Penicillium purpurogenum has substrate specificities toward acetate esters of d-xylopyranose residues in xylan and belongs to a new class of alpha/beta hydrolases. The crystal structure of AXEII has been determined by single isomorphous replacement and anomalous scattering, and refined at 0.90- and 1.10-A resolutions with data collected at 85 K and 295 K, respectively. The tertiary structure consists of a doubly wound alpha/beta sandwich, having a central six-stranded parallel beta-sheet flanked by two parallel alpha-helices on each side. The catalytic residues Ser(90), His(187), and Asp(175) are located at the C-terminal end of the sheet, an exposed region of the molecule. The serine and histidine side chains in the 295 K structure show the frequently observed conformations in which Ser(90) is trans and the hydroxyl group is in the plane of the imidazole ring of His(187). However, the structure at 85 K displays an additional conformation in which Ser(90) side-chain hydroxyl is away from the plane of the imidazole ring of His(187). The His(187) side chain forms a hydrogen bond with a sulfate ion and adopts an altered conformation. The only other known hydrolase that has a similar tertiary structure is Fusarium solani cutinase. The exposed nature of the catalytic triad suggests that AXEII is a pure esterase, i.e. an alpha/beta hydrolase with specificity for nonlipidic polar substrates.

PubMed: 11134051
DOI: 10.1074/jbc.M008831200

Experimental method

X-RAY DIFFRACTION (0.9 Å)