On the interaction between cytochrome f and plastocyanin

Zach Adam, Richard Malkin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

The interaction between cytochrome f and its electron acceptor plastocyanin (PC) was studied. To address the question of which specific regions and which of the positively charged residues of cytochrome f are important for the interaction with the negatively charged residues of PC we have used two different experimental approaches. Cytochrome f was proteolytically cleaved and fragments that could bind to a PC- affinity column were isolated. The smallest of these fragments was analysed to give information on the minimum structural requirement for binding to PC. By this procedure, we identified a peptide of approx. 11 kDa, containing the heme binding site, and having an N-terminal sequence identical to that of the mature cytochrome f. This finding suggests that the first 90 aminoacids of cytochrome f contain at least some of the residues interacting with PC. The second approach involved modification of Arg residues of cytochrome f with the specific chemical modifier, hydroxyphenylglyoxal (HPG). Cytochrome f modification was performed in the absence of PC to enable identification of residues that are protected from modification when PC is bound to cytochrome f. Two peptides containing Arg residues which are modified in the absence of PC, but are not modified when PC is present, were isolated. Sequence analysis of these two peptides revealed that Arg residues no. 88 and 154 of cytochrome f are the residues that are protected from modification when cytochrome f is bound to PC, suggesting a role for these residues in the binding of cytochrome f to PC.

Original languageAmerican English
Pages (from-to)158-163
Number of pages6
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume975
Issue number1
DOIs
StatePublished - Jun 1989
Externally publishedYes

Bibliographical note

Funding Information:
We wish to thank Dr. G. Hathaway of the Biotechnology Instrumentation Facility, U.C. Riverside, and Dr. A. Admon of the Howard Hughes Medical Institute, U.C. Berkeley for the "amino acid sequencing. This work was supported by a grant from the NIH to R.M.

Keywords

  • Chemical modification
  • Cytochrome f
  • Electron transport
  • Plastocyanin

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