TY - JOUR
T1 - Membrane-bound peptides mimicking transmembrane Vph1p helix 7 of yeast V-ATPase
T2 - A spectroscopic and polarity mismatch study
AU - Hesselink, Renske W.
AU - Koehorst, Rob B.M.
AU - Nazarov, Petr V.
AU - Hemminga, Marcus A.
N1 - Funding Information:
We acknowledge the European Commission for support under the Framework V, Quality of Life, initiative (QLRT-1999-31801). We thank Dr. Eefjan Breukink and Hester Hasper of the Department Biochemistry of Membranes, CBLE, IB, of Utrecht University for kindly providing the doxyl-labeled lipids used in the parallax analysis.
PY - 2005/10/15
Y1 - 2005/10/15
N2 - The V-ATPases are a family of ATP-dependent proton pumps, involved in a variety of cellular processes, including bone breakdown. V-ATPase enzymes that are too active in the latter process can result in osteoporosis, and inhibitors of the enzyme could be used to treat this disease. As a first step in studying the structure and function of the membrane-embedded interface at which proton translocation takes place, and its role in V-ATPase inhibition, synthetic peptides P1 and P2 consisting of 25 amino acid residues are presented here that mimic Vph1p helix 7 of yeast V-ATPase. A single mutation R10A between peptide P1 and P2 makes it possible to focus on the role of the essential arginine residue R735 in proton translocation. In the present work, we use a novel combination of spectroscopic techniques, such as CD spectroscopy, tryptophan emission spectra, acrylamide quenching and parallax analysis, and polarity mismatch modeling to characterize the peptides P1 and P2 in lipid bilayer systems. Based on both the spectroscopic experiments and the polarity mismatch modeling, P1 and P2 adopt a similar transmembrane conformation, with a mainly α-helical structure in the central part, placing the tryptophan residue at position 12 at a location 4 ± 2 Å from the centre of the lipid bilayer. Furthermore, the arginine at position 10 in P1 does not have an effect on the bilayer topology of the peptide, showing that the long, flexible side chain of this residue is able to snorkel towards the lipid headgroup region. This large flexibility of R735 might be important for its function in proton translocation in the V-ATPase enzyme.
AB - The V-ATPases are a family of ATP-dependent proton pumps, involved in a variety of cellular processes, including bone breakdown. V-ATPase enzymes that are too active in the latter process can result in osteoporosis, and inhibitors of the enzyme could be used to treat this disease. As a first step in studying the structure and function of the membrane-embedded interface at which proton translocation takes place, and its role in V-ATPase inhibition, synthetic peptides P1 and P2 consisting of 25 amino acid residues are presented here that mimic Vph1p helix 7 of yeast V-ATPase. A single mutation R10A between peptide P1 and P2 makes it possible to focus on the role of the essential arginine residue R735 in proton translocation. In the present work, we use a novel combination of spectroscopic techniques, such as CD spectroscopy, tryptophan emission spectra, acrylamide quenching and parallax analysis, and polarity mismatch modeling to characterize the peptides P1 and P2 in lipid bilayer systems. Based on both the spectroscopic experiments and the polarity mismatch modeling, P1 and P2 adopt a similar transmembrane conformation, with a mainly α-helical structure in the central part, placing the tryptophan residue at position 12 at a location 4 ± 2 Å from the centre of the lipid bilayer. Furthermore, the arginine at position 10 in P1 does not have an effect on the bilayer topology of the peptide, showing that the long, flexible side chain of this residue is able to snorkel towards the lipid headgroup region. This large flexibility of R735 might be important for its function in proton translocation in the V-ATPase enzyme.
KW - Arginine snorkeling
KW - Polarity mismatch simulation
KW - Protein-lipid interaction
KW - Transmembrane peptide
KW - Tryptophan location
KW - V-ATPase
UR - http://www.scopus.com/inward/record.url?scp=27444438697&partnerID=8YFLogxK
U2 - 10.1016/j.bbamem.2005.08.010
DO - 10.1016/j.bbamem.2005.08.010
M3 - Article
C2 - 16257593
AN - SCOPUS:27444438697
SN - 0005-2736
VL - 1716
SP - 137
EP - 145
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 2
ER -