4af7

PEA FNR C266M MUTANT

spinqualitylabelsall models 4af7, resolution 2.85Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4af7 is a 2 chain structure with sequence from Pisum sativum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.85Å Ligands: FAD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function FENR1_PEA May play a key role in regulating the relative amounts of cyclic and non-cyclic electron flow to meet the demands of the plant for ATP and reducing power. Publication Abstract from PubMed The role of the highly conserved C266 and L268 of pea ferredoxin-NADP(+) reductase (FNR) in formation of the catalytically competent complex of the enzyme with NADP(H) was investigated. Previous studies suggest that the volume of these side-chains, situated facing the side of the C-terminal Y308 catalytic residue not stacking the flavin isoalloxazine ring, may be directly involved in the fine-tuning of the catalytic efficiency of the enzyme. Wild-type pea FNR as well as single and double mutants of C266 and L268 residues were analysed by fast transient-kinetic techniques and their midpoint reduction potentials were determined. For the C266A, C266M and C266A/L268A mutants a significant reduction in the overall hydride transfer (HT) rates was observed along with the absence of charge-transfer complex formation. The HT rate constants for NADPH oxidation were lower than those for NADP(+) reduction, reaching a 30-fold decrease in the double mutant. In agreement, these variants exhibited more negative midpoint potentials with respect to the wild-type enzyme. The three-dimensional structures of C266M and L268V variants were solved. The C266M mutant shows a displacement of E306 away from the relevant residue S90 to accommodate the bulky methionine introduced. The overall findings indicate that in FNR the volume of the residue at position 266 is essential to attain the catalytic architecture between the nicotinamide and isoalloxazine rings at the active site and, therefore, for an efficient HT process. In addition, flexibility of the 268-270 loop appears to be critical for FNR to achieve catalytically competent complexes with NADP(H). Structural backgrounds for the formation of a catalytically competent complex with NADP(H) during hydride transfer in ferredoxin-NADP(+) reductases.,Sanchez-Azqueta A, Musumeci MA, Martinez-Julvez M, Ceccarelli EA, Medina M Biochim Biophys Acta. 2012 Apr 20;1817(7):1063-1071. PMID:22542899 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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