Structural highlights
Function
VPP1_YEAST Subunit of the V0 complex of vacuolar(H+)-ATPase (V-ATPase), a multisubunit enzyme composed of a peripheral complex (V1) that hydrolyzes ATP and a membrane integral complex (V0) that translocates protons (PubMed:1491220, PubMed:8798414, PubMed:11278748). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments (PubMed:1491220, PubMed:11278748). Is present only in vacuolar V-ATPase complexes; enzymes containing this subunit have a 4-fold higher ratio of proton transport to ATP hydrolysis than complexes containing the Golgi/endosomal isoform and undergo reversible dissociation of V1 and V0 in response to glucose depletion (PubMed:8798414, PubMed:11278748).[1] [2] [3]
Publication Abstract from PubMed
A 900-MHz NMR study is reported of peptide sMTM7 that mimics the cytoplasmic proton hemi-channel domain of the seventh transmembrane segment (TM7) from subunit a of H(+)-V-ATPase from Saccharomyces cerevisiae. The peptide encompasses the amino acid residues known to actively participate in proton translocation. In addition, peptide sMTM7 contains the amino acid residues that upon mutation cause V-ATPase to become resistant against the inhibitor bafilomycin. 2D TOCSY and NOESY (1)H-(1)H NMR spectra are obtained of sMTM7 dissolved in d(6)-DMSO and are used to calculate the three-dimensional structure of the peptide. The NMR-based structures and corresponding dynamical features of peptide sMTM7 show that sMTM7 is composed of two alpha-helical regions. These regions are separated by a flexible hinge of two residues. The hinge acts as a ball-and-joint socket and both helical segments move independently with respect to one another. This movement in TM7 is suggested to cause the opening and closing of the cytoplasmic proton hemi-channel and enables proton translocation.
Segment TM7 from the cytoplasmic hemi-channel from VO-H+-V-ATPase includes a flexible region that has a potential role in proton translocation.,Duarte AM, de Jong ER, Wechselberger R, van Mierlo CP, Hemminga MA Biochim Biophys Acta. 2007 Sep;1768(9):2263-70. Epub 2007 May 21. PMID:17573038[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Kawasaki-Nishi S, Nishi T, Forgac M. Yeast V-ATPase complexes containing different isoforms of the 100-kDa a-subunit differ in coupling efficiency and in vivo dissociation. J Biol Chem. 2001 May 25;276(21):17941-8. Epub 2001 Mar 2. PMID:11278748 doi:http://dx.doi.org/10.1074/jbc.M010790200
- ↑ Manolson MF, Proteau D, Jones EW. Evidence for a conserved 95-120 kDa subunit associated with and essential for activity of V-ATPases. J Exp Biol. 1992 Nov;172:105-12. PMID:1491220
- ↑ Leng XH, Manolson MF, Liu Q, Forgac M. Site-directed mutagenesis of the 100-kDa subunit (Vph1p) of the yeast vacuolar (H+)-ATPase. J Biol Chem. 1996 Sep 13;271(37):22487-93. PMID:8798414
- ↑ Duarte AM, de Jong ER, Wechselberger R, van Mierlo CP, Hemminga MA. Segment TM7 from the cytoplasmic hemi-channel from VO-H+-V-ATPase includes a flexible region that has a potential role in proton translocation. Biochim Biophys Acta. 2007 Sep;1768(9):2263-70. Epub 2007 May 21. PMID:17573038 doi:http://dx.doi.org/S0005-2736(07)00183-6
