Amino acid residues responsible for the different pH dependency of cell-specific ferredoxins in the electron transfer reaction with ferredoxin-NADP+ reductase from maize leaves.
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引用次数: 0
Abstract
In the chloroplast stroma, dynamic pH changes occur from acidic to alkaline in response to fluctuating light conditions. We investigated the pH dependency of the electron transfer reaction of ferredoxin-NADP+ reductase (FNR) with ferredoxin (Fd) isoproteins, Fd1 and Fd2, which are localized in mesophyll cells and bundle sheath cells, respectively, in the leaves of C4 plant maize. The pH-dependent profile of the electron transfer activity with FNR was quite different between Fd1 and Fd2, which was mainly explained by the opposite pH dependency of the Km value of these Fds for FNR. Replacement of the amino acid residue at position of 65 (D65N) and 78 (H78A) between the two Fds conferred different effect on their pH dependency of the Km value. Double mutations of the two residues between Fd1 and Fd2 (Fd1D65N/H78A and Fd2N65D/A78H) led to the mutual exchange of the pH dependency of the electron transfer activity. This exchange was mainly explained by the changes in the pH-dependent profile of the Km values. Therefore, the differences in Asp/Asn at position 65 and His/Ala at position 78 between Fd1 and Fd2 were shown to be the major determinants for their different pH dependency in the electron transfer reaction with FNR.
期刊介绍:
The Journal of Biochemistry founded in 1922 publishes the results of original research in the fields of Biochemistry, Molecular Biology, Cell, and Biotechnology written in English in the form of Regular Papers or Rapid Communications. A Rapid Communication is not a preliminary note, but it is, though brief, a complete and final publication. The materials described in Rapid Communications should not be included in a later paper. The Journal also publishes short reviews (JB Review) and papers solicited by the Editorial Board.