title: Structure and function of subunit a of the ATP synthase of Escherichia coli.
abstract: The structure of subunit a of the Escherichia coli ATP synthase has been probed by construction of more than one hundred monocysteine substitutions. Surface labeling with 3-N-maleimidyl-propionyl biocytin (MPB) has defined five transmembrane helices, the orientation of the protein in the membrane, and information about the relative exposure of the loops connecting these helices. Cross-linking studies using TFPAM-3 (N-(4-azido-2,3,5,6-tetrafluorobenzyl)-3-maleimido-propionamide) and benzophenone-4-maleimide have revealed which elements of subunit a are near subunits b and c. Use of a chemical protease reagent, 5-(-bromoacetamido)-1,10-phenanthroline-copper, has indicated that the periplasmic end of transmembrane helix 5 is near that of transmembrane helix 2.
authors.affiliation: Department of Biological Sciences, Southern Methodist University, Dallas, Texas 75275-0376, USA. svik@smu.edu
authors.forename: Steven B
authors.initials: SB
authors.lastname: Vik
authors.forename: Robert R
authors.initials: RR
authors.lastname: Ishmukhametov
mesh_terms: D025243:Bacterial Proton-Translocating ATPases; D003545:Cysteine; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry; D025261:Mitochondrial Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D021122:Protein Subunits; D025243:Bacterial Proton-Translocating ATPases; D025261:Mitochondrial Proton-Translocating ATPases; C074428:atpB protein, E coli; D003545:Cysteine