H+/Lactose Membrane Transport Protein, LacY
Living reference work entry
First Online:
DOI: https://doi.org/10.1007/978-3-642-35943-9_665-1
Synonyms
Definition
LacY (
aka Lac permease) is the product of the
lacY gene, the second structural gene in the
lac operon, which encodes a single polypeptide that is solely responsible for all the translocation reactions of
β-galactoside transport in
E. coli. LacY (TCDB 2.A.1.5.1) belongs to the oligosaccharide/H
+ symporter subfamily of the major facilitator superfamily (MFS). LacY is selective for disaccharides containing a d-galactopyranosyl ring, as well as d-galactose, with no affinity for d-glucopyranosides or d-glucose. The native substrate is lactose, which is a disaccharide derived from the condensation of galactose and glucose at a β-1 → 4 glycosidic linkage. The systematic name is β-d-galactopyranosyl-(1 → 4)-d-glucose (Fig.
1). LacY catalyzes reversible translocations of one cargo sugar with one proton (H
+), and the coupled translocation between H
+and the sugar in the same direction is obligatory. The reaction can be described by the...
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References
- Abramson J, Smirnova I, Kasho V, Verner G, Kaback HR, Iwata S (2003) Structure and mechanism of the lactose permease of Escherichia coli. Science 301:610–615CrossRefPubMedGoogle Scholar
- Carrasco N, Antes LM, Poonian MS, Kaback HR (1986) Lac permease of Escherichia coli: histidine-322 and glutamic acid-325 may be components of a charge-relay system. Biochemistry 25:4486–4488CrossRefPubMedGoogle Scholar
- Chaptal V, Kwon S, Sawaya MR, Guan L, Kaback HR, Abramson J (2011) Crystal structure of lactose permease in complex with an affinity inactivator yields unique insight into sugar recognition. Proc Natl Acad Sci U S A 108:9361–9366CrossRefPubMedPubMedCentralGoogle Scholar
- Frillingos S, Sahin-Toth M, Wu J, Kaback HR (1998) Cys-scanning mutagenesis: a novel approach to structure function relationships in polytopic membrane proteins. FASEB J 12:1281–1299CrossRefPubMedGoogle Scholar
- Gaiko O, Bazzone A, Fendler K, Kaback HR (2013) Electrophysiological characterization of uncoupled mutants of LacY. Biochemistry 52:8261–8266CrossRefPubMedGoogle Scholar
- Garcia-Celma JJ, Smirnova IN, Kaback HR, Fendler K (2009) Electrophysiological characterization of LacY. Proc Natl Acad Sci U S A 106:7373–7378CrossRefPubMedPubMedCentralGoogle Scholar
- Garcia-Celma JJ, Ploch J, Smirnova I, Kaback HR, Fendler K (2010) Delineating electrogenic reactions during lactose/H+ symport. Biochemistry 49:6115–6121CrossRefPubMedPubMedCentralGoogle Scholar
- Grytsyk N, Sugihara J, Kaback HR, Hellwig P (2017) pKa of Glu325 in LacY. Proc Natl Acad Sci U S A 114:1530–1535CrossRefPubMedPubMedCentralGoogle Scholar
- Guan L, Kaback HR (2004) Binding affinity of lactose permease is not altered by the H+ electrochemical gradient. Proc Natl Acad Sci U S A 101:12148–12152CrossRefPubMedPubMedCentralGoogle Scholar
- Guan L, Kaback HR (2006) Lessons from lactose permease. Annu Rev Biophys Biomol Struct 35:67–91CrossRefPubMedPubMedCentralGoogle Scholar
- Guan L, Hu Y, Kaback HR (2003a) Aromatic stacking in the sugar binding site of the lactose permease. Biochemistry 42:1377–1382CrossRefPubMedGoogle Scholar
- Guan L, Sahin-Toth M, Kalai T, Hideg K, Kaback HR (2003b) Probing the mechanism of a membrane transport protein with affinity inactivators. J Biol Chem 278:10641–10648CrossRefPubMedGoogle Scholar
- Guan L, Mirza O, Verner G, Iwata S, Kaback HR (2007) Structural determination of wild-type lactose permease. Proc Natl Acad Sci U S A 104:15294–15298CrossRefPubMedPubMedCentralGoogle Scholar
- von Heijne G (1992) Membrane protein structure prediction. Hydrophobicity analysis and the positive-inside rule. J Mol Biol 225:487–494CrossRefGoogle Scholar
- Kaback HR (2015) A chemiosmotic mechanism of symport. Proc Natl Acad Sci U S A 112:1259–1264CrossRefPubMedPubMedCentralGoogle Scholar
- Kaback HR, Sahin-Toth M, Weinglass AB (2001) The kamikaze approach to membrane transport. Nat Rev Mol Cell Biol 2:610–620CrossRefPubMedGoogle Scholar
- Kaczorowski GJ, Kaback HR (1979) Mechanism of lactose translocation in membrane vesicles from Escherichia coli. 1. Effect of pH on efflux, exchange, and counterflow. Biochemistry 18:3691–3697CrossRefPubMedGoogle Scholar
- Kumar H, Kasho V, Smirnova I, Finer-Moore JS, Kaback HR, Stroud RM (2014) Structure of sugar-bound LacY. Proc Natl Acad Sci U S A 111:1784–1788CrossRefPubMedPubMedCentralGoogle Scholar
- Kumar H, Finer-Moore JS, Kaback HR, Stroud RM (2015) Structure of LacY with an alpha-substituted galactoside: connecting the binding site to the protonation site. Proc Natl Acad Sci U S A 112:9004–9009CrossRefPubMedPubMedCentralGoogle Scholar
- Nie Y, Kaback HR (2010) Sugar binding induces the same global conformational change in purified LacY as in the native bacterial membrane. Proc Natl Acad Sci U S A 107:9903–9908CrossRefPubMedPubMedCentralGoogle Scholar
- Robertson DE, Kaczorowski GJ, Garcia ML, Kaback HR (1980) Active transport in membrane vesicles from Escherichia coli: the electrochemical proton gradient alters the distribution of the lac carrier between two different kinetic states. Biochemistry 19:5692–5702CrossRefPubMedGoogle Scholar
- Sahin-Toth M, Akhoon KM, Runner J, Kaback HR (2000) Ligand recognition by the lactose permease of Escherichia coli: specificity and affinity are defined by distinct structural elements of galactopyranosides. Biochemistry 39:5097–5103CrossRefPubMedGoogle Scholar
- Sahin-Toth M, Lawrence MC, Nishio T, Kaback HR (2001) The C-4 hydroxyl group of galactopyranosides is the major determinant for ligand recognition by the lactose permease of Escherichia coli. Biochemistry 40:13015–13019CrossRefPubMedGoogle Scholar
- Smirnova IN, Kasho V, Kaback HR (2008) Protonation and sugar binding to LacY. Proc Natl Acad Sci U S A 105:8896–8901CrossRefPubMedPubMedCentralGoogle Scholar
- Smirnova I, Kasho V, Sugihara J, Choe JY, Kaback HR (2009) Residues in the H(+) translocation site define the pKa for sugar binding to LacY. Biochemistry 48:8852–8860CrossRefPubMedPubMedCentralGoogle Scholar
- Smirnova I, Kasho V, Kaback HR (2011) Lactose permease and the alternating access mechanism. Biochemistry 50:9684–9693CrossRefPubMedPubMedCentralGoogle Scholar
- Smirnova I, Kasho V, Sugihara J, Kaback HR (2013) Trp replacements for tightly interacting Gly-Gly pairs in LacY stabilize an outward-facing conformation. Proc Natl Acad Sci U S A 110:8876–8881CrossRefPubMedPubMedCentralGoogle Scholar
- Smirnova I, Kasho V, Jiang X, Kaback HR (2017) An asymmetric conformational change in LacY. Biochemistry 56:1943–1950CrossRefPubMedPubMedCentralGoogle Scholar
- Vazquez-Ibar JL, Guan L, Svrakic M, Kaback HR (2003) Exploiting luminescence spectroscopy to elucidate the interaction between sugar and a tryptophan residue in the lactose permease of Escherichia coli. Proc Natl Acad Sci U S A 100:12706–12711CrossRefPubMedPubMedCentralGoogle Scholar
- Viitanen P, Garcia ML, Foster DL, Kaczorowski GJ, Kaback HR (1983) Mechanism of lactose translocation in proteoliposomes reconstituted with lac carrier protein purified from Escherichia coli. 2. Deuterium solvent isotope effects. Biochemistry 22:2531–2536CrossRefPubMedGoogle Scholar
- Weinglass AB, Whitelegge JP, Hu Y, Verner GE, Faull KF, Kaback HR (2003) Elucidation of substrate binding interactions in a membrane transport protein by mass spectrometry. EMBO J 22:1467–1477CrossRefPubMedPubMedCentralGoogle Scholar
- Yousef MS, Guan L (2009) A 3D structure model of the melibiose permease of Escherichia coli represents a distinctive fold for Na(+) symporters. Proc Natl Acad Sci U S A 106:15291–15296CrossRefPubMedPubMedCentralGoogle Scholar
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