Fine tuning of coenzyme specificity in family 2 aldo-keto reductases revealed by crystal structures of the Lys-274 → Arg mutant of Candida tenuis xylose reductase (AKR2B5) bound to NAD + and NADP +
Aldo-keto reductases of family 2 employ single site replacement Lys → Arg to switch their cosubstrate preference from NADPH to NADH. X-ray crystal structures of Lys-274 → Arg mutant of Candida tenuis xylose reductase (AKR2B5) bound to NAD+ and NADP+ were determined at a resolution of 2.4 and 2.3 Å, respectively. Due to steric conflicts in the NADP+-bound form, the arginine side chain must rotate away from the position of the original lysine side chain, thereby disrupting a network of direct and water-mediated interactions between Glu-227, Lys-274 and the cofactor 2'-phosphate and 3'-hydroxy groups. Because anchoring contacts of its Glu-227 are lost, the coenzyme-enfolding loop that becomes ordered upon binding of NAD(P)+ in the wild-type remains partly disordered in the NADP+-bound mutant. The results delineate a catalytic reaction profile for the mutant in comparison to wild-type.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 890432
- Report Number(s):
- SLAC-REPRINT-2005-075; TRN: US200620%%462
- Journal Information:
- FEBS Letters, Vol. 579, Issue 3; ISSN 0014-5793
- Country of Publication:
- United States
- Language:
- English
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