PDBsum entry 1wp1

Membrane protein

PDB id: 1wp1

Contents

Protein chains

456 a.a. *

405 a.a. *

Waters ×24

* Residue conservation analysis

PDB id:

1wp1

Name:

Membrane protein

Title:

Crystal structure of the drug-discharge outer membrane protein, oprm

Structure:

Outer membrane protein oprm. Chain: a, b. Synonym: drug-discharge outer membrane protein oprm. Engineered: yes

Source:

Pseudomonas aeruginosa. Organism_taxid: 287. Gene: oprm. Expressed in: pseudomonas aeruginosa. Expression_system_taxid: 287.

Biol. unit:

Trimer (from PDB file)

Resolution:

2.56Å R-factor: 0.255 R-free: 0.308

Authors:

H.Akama,M.Kanemaki,M.Yoshimura,T.Tsukihara,T.Kashiwagi,S.Narita, A.Nakagawa,T.Nakae

Key ref:

H.Akama et al. (2004). Crystal structure of the drug discharge outer membrane protein, OprM, of Pseudomonas aeruginosa: dual modes of membrane anchoring and occluded cavity end. J Biol Chem, 279, 52816-52819. PubMed id: 15507433 DOI: 10.1074/jbc.C400445200

Date:

28-Aug-04 Release date: 02-Nov-04

Protein chain

Q51487  (OPRM_PSEAE) -  Outer membrane protein OprM from Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)

Seq: 485 a.a.

Struc: 456 a.a.

Protein chain

Q51487  (OPRM_PSEAE) -  Outer membrane protein OprM from Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)

Seq: 485 a.a.

Struc: 405 a.a.

DOI no: 10.1074/jbc.C400445200

J Biol Chem 279:52816-52819 (2004)

PubMed id: 15507433

Crystal structure of the drug discharge outer membrane protein, OprM, of Pseudomonas aeruginosa: dual modes of membrane anchoring and occluded cavity end.

H.Akama, M.Kanemaki, M.Yoshimura, T.Tsukihara, T.Kashiwagi, H.Yoneyama, S.Narita, A.Nakagawa, T.Nakae.

ABSTRACT

The OprM lipoprotein of Pseudomonas aeruginosa is a member of the MexAB-OprM xenobiotic-antibiotic transporter subunits that is assumed to serve as the drug discharge duct across the outer membrane. The channel structure must differ from that of the porin-type open pore because the protein facilitates the exit of antibiotics but not the entry. For better understanding of the structure-function linkage of this important pump subunit, we studied the x-ray crystallographic structure of OprM at the 2.56-angstroms resolution. The overall structure exhibited trimeric assembly of the OprM monomer that consisted mainly of two domains: the membrane-anchoring beta-barrel and the cavity-forming alpha-barrel. OprM anchors the outer membrane by two modes of membrane insertions. One is via the covalently attached NH(2)-terminal fatty acids and the other is the beta-barrel structure consensus on the outer membrane-spanning proteins. The beta-barrel had a pore opening with a diameter of about 6-8 angstroms, which is not large enough to accommodate the exit of any antibiotics. The periplasmic alpha-barrel was about 100 angstroms long formed mainly by a bundle of alpha-helices that formed a solvent-filled cavity of about 25,000 angstroms(3). The proximal end of the cavity was tightly sealed, thereby not permitting the entry of any molecule. The result of this structure was that the resting state of OprM had a small outer membrane pore and a tightly closed periplasmic end, which sounds plausible because the protein should not allow free access of antibiotics. However, these observations raised another unsolved problem about the mechanism of opening of the OprM cavity ends. The crystal structure offers possible mechanisms of pore opening and pump assembly.

Selected figure(s)

Figure 2.
FIG. 2. OprM cavity and the cavity ends. A, vertical views and horizontal slices of the OprM trimer. Three monomers are colored blue, red, and green. The left figure shows a vertical view of the OprM trimer. The right figures exhibited horizontal slices of the OprM trimer at the -barrel, equator, and the periplasmic end. Approximate pore diameters are shown. B, periplasmic end of the OprM trimer. Triplet Leu412 residues are shown by the space-filling model (yellow). The remaining amino acid residues are shown by a stick model.

Figure 4.
FIG. 4. Stereoscopic view of the OprM-MexB junction. Side view of the OprM-MexB junction in the trimeric form was shown. Arrays of hydrophobic amino acids, Val198-Gly199-Val200 of OprM (red, magenta, and yellow) and that of Ala^736-Leu737-Gly738 of MexB (blue, cyan, and white) were shown by the space-filling model.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 52816-52819) copyright 2004.

Figures were selected by the author.