PDBsum entry 4zyr

Transport protein

PDB id: 4zyr

Contents

Protein chains

387 a.a.

Ligands

9PG ×2

BNG ×2

PDB id:

4zyr

Name:

Transport protein

Title:

Crystal structure of e. Coli lactose permease g46w/g262w bound to p- nitrophenyl alpha-d-galactopyranoside (alpha-npg)

Structure:

Lactose permease. Chain: a, b. Synonym: lactose-proton symport. Engineered: yes. Mutation: yes

Source:

Escherichia coli (strain k12). Organism_taxid: 83333. Strain: k12. Gene: lacy, b0343, jw0334. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

3.31Å R-factor: 0.260 R-free: 0.278

Authors:

H.Kumar,J.S.Finer-Moore,H.R.Kaback,R.M.Stroud

Key ref:

H.Kumar et al. (2015). Structure of LacY with an α-substituted galactoside: Connecting the binding site to the protonation site. Proc Natl Acad Sci U S A, 112, 9004-9009. PubMed id: 26157133 DOI: 10.1073/pnas.1509854112

Date:

22-May-15 Release date: 29-Jul-15

Protein chains

P02920  (LACY_ECOLI) -  Lactose permease from Escherichia coli (strain K12)

Seq: 417 a.a.

Struc: 387 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

DOI no: 10.1073/pnas.1509854112

Proc Natl Acad Sci U S A 112:9004-9009 (2015)

PubMed id: 26157133

Structure of LacY with an α-substituted galactoside: Connecting the binding site to the protonation site.

H.Kumar, J.S.Finer-Moore, H.R.Kaback, R.M.Stroud.

ABSTRACT

The X-ray crystal structure of a conformationally constrained mutant of the Escherichia coli lactose permease (the LacY double-Trp mutant Gly-46→Trp/Gly-262→Trp) with bound p-nitrophenyl-α-d-galactopyranoside (α-NPG), a high-affinity lactose analog, is described. With the exception of Glu-126 (helix IV), side chains Trp-151 (helix V), Glu-269 (helix VIII), Arg-144 (helix V), His-322 (helix X), and Asn-272 (helix VIII) interact directly with the galactopyranosyl ring of α-NPG to provide specificity, as indicated by biochemical studies and shown directly by X-ray crystallography. In contrast, Phe-20, Met-23, and Phe-27 (helix I) are within van der Waals distance of the benzyl moiety of the analog and thereby increase binding affinity nonspecifically. Thus, the specificity of LacY for sugar is determined solely by side-chain interactions with the galactopyranosyl ring, whereas affinity is increased by nonspecific hydrophobic interactions with the anomeric substituent.