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Modulation of copper site properties by remote residues determines the stability of plastocyanins
Author(s) -
Muñoz-López Francisco J.,
Beltrán Estrella Frutos,
Díaz-Moreno Sofía,
Díaz-Moreno Irene,
Subías Gloria,
De la Rosa Miguel A.,
Díaz-Quintana Antonio
Publication year - 2010
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2010.04.013
Subject(s) - plastocyanin , copper protein , copper , chemistry , redox , electron transfer , cofactor , synechocystis , crystallography , photochemistry , biochemistry , inorganic chemistry , photosystem ii , photosystem i , organic chemistry , photosynthesis , enzyme , mutant , gene
The metal cofactor determines the thermal stability in cupredoxins, but how the redox state of copper modulates their melting points remains unknown. The metal coordination environment is highly conserved in cyanobacterial plastocyanins. However, the oxidised form is more stable than the reduced one in thermophilic Phormidium , but the opposite occurs in mesophilic Synechocystis . We have performed neutral amino‐acid substitutions at loops of Phormidium plastocyanin far from the copper site. Notably, mutation P49G/G50P confers a redox‐dependent thermal stability similar to that of the mesophilic plastocyanin. Moreover, X‐ray absorption spectroscopy reveals that P49G/G50P mutation makes the electron density distribution at the oxidised copper site shift towards that of Synechocystis plastocyanin.