title: Location of a dicyclohexylcarbodiimide-reactive glutamate residue in the Neurospora crassa plasma membrane H+-ATPase.
abstract: The proton pump (H+-ATPase) found in the plasma membrane of the fungus Neurospora crassa is inactivated by dicyclohexylcarbodiimide (DCCD). Kinetic and labeling experiments have suggested that inactivation at 0 degrees C results from the covalent attachment of DCCD to a single site in the Mr = 100,000 catalytic subunit (Sussman, M. R., and Slayman, C. W. (1983) J. Biol. Chem. 258, 1839-1843). In the present study, when [14C]DCCD-labeled enzyme was treated with the cleavage reagent, N-bromosuccinimide, a single major radioactive peptide fragment migrating at about Mr = 5,300 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was produced. The fragment was coupled to glass beads and partially sequenced by automated solid-phase Edman degradation at the amino terminus and at an internal tryptic cleavage site. By comparison to the DNA-derived amino acid sequence for the entire Mr = 100,000 polypeptide (Hager, K., and Slayman, C. W. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 7693-7697), the fragment has been identified as arising by cleavage at tyrosine 100 and tryptophan 141. Covalently incorporated [14C]DCCD was released at a position corresponding to glutamate 129. The DCCD-reactive glutamate is located in the middle of the first of eight predicted transmembrane sequences. When the sequence surrounding the DCCD site is compared to that surrounding the DCCD-reactive residue of two other proton pumps, the F0F1-ATPase and cytochrome c oxidase, no homology is apparent apart from an abundance of hydrophobic amino acids.
mesh_terms: D001665:Binding Sites; D002234:Carbodiimides / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004024:Dicyclohexylcarbodiimide / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D008970:Molecular Weight; D009491:Neurospora / Q000378:metabolism*; D009492:Neurospora crassa / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D002234:Carbodiimides; D005971:Glutamates; D018698:Glutamic Acid; D004024:Dicyclohexylcarbodiimide; D006180:Proton-Translocating ATPases