3Q67

Human Aldose Reductase C298S mutant in Complex with NADP+ in Space Group P212121

Summary for 3Q67

• Entry DOI: 10.2210/pdb3q67/pdb
• Related: 3Q65
• Descriptor: Aldose reductase, NADP NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE, SULFATE ION, ... (4 entities in total)
• Functional Keywords: alpha/beta barrel, oxidoreductase
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: P15121
• Total number of polymer chains: 2
• Total formula weight: 74019.87

Authors

Sawaya, M.R.,Cascio, D.,Balendiran, G.K. (deposition date: 2010-12-30, release date: 2011-01-12, Last modification date: 2024-02-21)

Primary citation

Balendiran, G.K.,Sawaya, M.R.,Schwarz, F.P.,Ponniah, G.,Cuckovich, R.,Verma, M.,Cascio, D.
The role of Cys-298 in aldose reductase function.
J.Biol.Chem., 286:6336-6344, 2011

PubMed Abstract: Diabetic tissues are enriched in an "activated" form of human aldose reductase (hAR), a NADPH-dependent oxidoreductase involved in sugar metabolism. Activated hAR has reduced sensitivity to potential anti-diabetes drugs. The C298S mutant of hAR reproduces many characteristics of activated hAR, although it differs from wild-type hAR only by the replacement of a single sulfur atom with oxygen. Isothermal titration calorimetry measurements revealed that the binding constant of NADPH to the C298S mutant is decreased by a factor of two, whereas that of NADP(+) remains the same. Similarly, the heat capacity change for the binding of NADPH to the C298S mutant is twice increased; however, there is almost no difference in the heat capacity change for binding of the NADP(+) to the C298S. X-ray crystal structures of wild-type and C298S hAR reveal that the side chain of residue 298 forms a gate to the nicotinamide pocket and is more flexible for cysteine compared with serine. Unlike Cys-298, Ser-298 forms a hydrogen bond with Tyr-209 across the nicotinamide ring, which inhibits movements of the nicotinamide. We hypothesize that the increased polarity of the oxidized nicotinamide weakens the hydrogen bond potentially formed by Ser-298, thus, accounting for the relatively smaller effect of the mutation on NADP(+) binding. The effects of the mutant on catalytic rate constants and binding constants for various substrates are the same as for activated hAR. It is, thus, further substantiated that activated hAR arises from oxidative modification of Cys-298, a residue near the nicotinamide binding pocket.

PubMed: 21084309
DOI: 10.1074/jbc.M110.154195

Experimental method

X-RAY DIFFRACTION (1.55 Å)