3mhp | pdb_00003mhp
FNR-recruitment to the thylakoid
Structural highlights
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. [TIC62_PEA] Involved in protein precursor import into chloroplasts. Part of the redox regulon consisting of TIC32, TIC 55 and TIC62. Has a NADPH-dependent dehydrogenase activity, but only after preincubation with lipids.[1] [2] Publication Abstract from PubMedFerredoxin:NADPH oxidoreductase (FNR) is a key enzyme of photosynthetic electron transport required for generation of reduction equivalents. Recently, two proteins were found to be involved in membrane-anchoring of FNR by specific interaction via a conserved Ser/Pro-rich motif: Tic62 and Trol. Our crystallographic study reveals that the FNR-binding motif, which forms a polyproline type II helix, induces self-assembly of two FNR monomers into a back-to-back dimer. Because binding occurs opposite to the FNR active sites, its activity is not affected by the interaction. Surface plasmon resonance analyses disclose a high affinity of FNR to the binding motif, which is strongly increased under acidic conditions. The pH of the chloroplast stroma changes dependent on the light conditions from neutral to slightly acidic in complete darkness or to alkaline at saturating light conditions. Recruiting of FNR to the thylakoids could therefore represent a regulatory mechanism to adapt FNR availability/activity to photosynthetic electron flow. Ferredoxin:NADPH oxidoreductase is recruited to thylakoids by binding to a polyproline type II helix in a pH-dependent manner.,Alte F, Stengel A, Benz JP, Petersen E, Soll J, Groll M, Bolter B Proc Natl Acad Sci U S A. 2010 Nov 9;107(45):19260-5. Epub 2010 Oct 25. PMID:20974920[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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