Substrate specificity and subsite mobility in T. aurantiacus xylanase 10A

FEBS Letters

Kalogiannis, Stavros³  Lo Leggio, Leila⁵  Andrei, Carmen⁵  Pickersgill, Richard W¹  Bhat, Mahalingeswara K²  Larsen, Sine⁵  Eckert, Kelvin⁵  Teixeira, Susana C.M⁴ 

[1] Biological Sciences, Medical Science Building, Queen Mary University of London, London E1 4NS, UK;Institute of Food Research, Norwich Research Park, Colney Lane, Norwich NR4 7UA, UK;Hellenic Sugar Industry S.A., Agricultural Research Centre, Laboratory of Industrial Microbiology, Thessaloniki, Greece;Chemistry Department, University of Reading, Whiteknights, Reading RG6 6AD, UK;Centre for Crystallographic Studies, Chemical Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark

关键词: Family 10;    Tryptophan;    Enzyme–substrate complex;    Glycerol;    Specificity;    Glycoside hydrolase;    TAX;    Thermoascus aurantiacus xylanase I;    GLC;    TAX structure in complex with glycerol collected at cryogenic temperature;    XBRT;    TAX structure in complex with xylobiose collected at room temperature;    XBCRYO;    TAX structure in complex with xylobiose collected at cryogenic temperature;    CEX;    xylanase/exocellulase Cex from Clostridium fimi;    CMC;    carboxymethylcellulose;    pNP;    p-nitrophenyl;    RSCC;    real space correlation coefficient calculated in CNS against a Sigmaa 2F obs−F calc map;   

DOI  :  10.1016/S0014-5793(01)03177-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The substrate specificity of Thermoascus aurantiacus xylanase 10A (TAX) has been investigated both biochemically and structurally. High resolution crystallographic analyses at 291 K and 100 K of TAX complexes with xylobiose show that the ligand is in its α anomeric conformation and provide a rationale for specificity on p-nitrophenyl glycosides at the −1 and −2 subsites. Trp 275, which is disordered in uncomplexed structures, is stabilised by its interaction with xylobiose. Two structural subsets in family 10 are identified, which differ by the presence or absence of a short helical stretch in the eighth βα-loop of the TIM barrel, the loop bearing Trp 275. This structural difference is discussed in the context of Trp 275 mobility and xylanase function.

【 授权许可】

Unknown