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 alpha anomeric conformation and provide a rationale for specificity on p-nitrophenyl glycosides at the -1 and -2 subsites ...
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 alpha 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 betaalpha-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.
Related Citations:
Anisotropic refinement of the structure of Thermoascus aurantiacus xylanase I Teixeira, S.C.M., Lo Leggio, L., Pickersgill, R., Cardin, C. (2001) Acta Crystallogr D Biol Crystallogr 57: 385
High Resolution Structure and Sequence of T.aurantiacus Xylanase I: Implications for the Evolution of thermostability in Family 10 xylanases and enzymes with (beta)alpha-barrel architecture Lo Leggio, L., Kalogiannis, S., Bhat, M.K., Pickersgill, R.W. (1999) Proteins 36: 295
Crystal Structure at 1.8A resolution and proposed amino acid sequence of a thermostable xylanase from Thermoascus aurantiacus Natesh, R., Bhanumoorthy, P., Vithayathil, P.J., Sekar, K., Ramakumar, S., Viswamitra, M.A. (1999) J Mol Biol 288: 999
Organizational Affiliation:
Centre for Crystallographic Studies, Chemical Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark. leila@ccs.ki.ku.dk
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