Identification of the P-loop lysine as a metal ligand in the absence of nucleotide at catalytic site 3 of chloroplast F1-ATPase from Chlamydomonas reinhardtii

D. J. Crampton, R. Lobrutto, Wayne Frasch

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5 Scopus citations

Abstract

Site-directed mutations were made to the phosphate-binding loop lysine in the β-subunit of the chloroplast F1-ATPase in Chlamydomonas reinhardtii (βK167) to investigate the participation of this residue in the binding of metal to catalytic site 3 in the absence of nucleotide. The cw-EPR spectra of VO2+ bound to site 3 of CF1-ATPase from wild type and mutants revealed changes in metal ligation resulting from mutations to βK167. The three-pulse ESEEM spectrum of the wild-type CF1-ATPase with VO2+ bound to site 3 shows an equatorially coordinating 14N from an amine. The ESEEM spectra of the mutants do not show evidence of an equatorially coordinating amine group. The results presented here show that, in the absence of nucleotide, βK167 is a ligand to the metal bound at catalytic site 3, suggesting a regulatory role for the P-loop lysine in addition to its known role in catalysis.

Original languageEnglish (US)
Pages (from-to)3710-3716
Number of pages7
JournalBiochemistry
Volume40
Issue number12
DOIs
StatePublished - Mar 27 2001

ASJC Scopus subject areas

  • Biochemistry

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