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Toward understanding the outer membrane uptake of small molecules by Pseudomonas aeruginosa

Toward understanding the outer membrane uptake of small molecules by Pseudomonas aeruginosa
Toward understanding the outer membrane uptake of small molecules by Pseudomonas aeruginosa
Because small molecules enter Gram-negative bacteria via outer membrane (OM) channels, understanding OM transport is essential for the rational design of improved and new antibiotics. In the human pathogen Pseudomonas aeruginosa, most small molecules are taken up by outer membrane carboxylate channel (Occ) proteins, which can be divided into two distinct subfamilies, OccD and OccK. Here we characterize substrate transport mediated by Occ proteins belonging to both subfamilies. Based on the determination of the OccK2-glucuronate co-crystal structure, we identify the channel residues that are essential for substrate transport. We further show that the pore regions of the channels are rigid in the OccK subfamily and highly dynamic in the OccD subfamily. We also demonstrate that the substrate carboxylate group interacts with central residues of the basic ladder, a row of arginine and lysine residues that leads to and away from the binding site at the channel constriction. Moreover, the importance of the basic ladder residues corresponds to their degree of conservation. Finally, we apply the generated insights by converting the archetype of the entire family, OccD1, from a basic amino acid-specific channel into a channel with a preference for negatively charged amino acids.
Antibiotics, membrane proteins, membrane transport, pseudomonas aeruginosa, x-ray crystallography, occ family, oprd, crystal structure, outer membrane channels
0021-9258
12042-12053
Eren, E.
7a11b792-2ebb-47f0-aca7-3d2f5e87e129
Parkin, J.
f321305b-95ce-4035-9ac2-103a352630cc
Adelanwa, A.
64b98ffb-d2a2-41a9-859d-e8506564fdc6
Cheneke, B.
874b94c7-52c5-4204-a0f0-55061f481288
Movileanu, L.
6a96227f-16a3-4401-8107-8ab22b366c42
Khalid, S.
90fbd954-7248-4f47-9525-4d6af9636394
van den Berg, B.
116443cd-051d-439a-87d2-b1213b6929fe
Eren, E.
7a11b792-2ebb-47f0-aca7-3d2f5e87e129
Parkin, J.
f321305b-95ce-4035-9ac2-103a352630cc
Adelanwa, A.
64b98ffb-d2a2-41a9-859d-e8506564fdc6
Cheneke, B.
874b94c7-52c5-4204-a0f0-55061f481288
Movileanu, L.
6a96227f-16a3-4401-8107-8ab22b366c42
Khalid, S.
90fbd954-7248-4f47-9525-4d6af9636394
van den Berg, B.
116443cd-051d-439a-87d2-b1213b6929fe

Eren, E., Parkin, J., Adelanwa, A., Cheneke, B., Movileanu, L., Khalid, S. and van den Berg, B. (2013) Toward understanding the outer membrane uptake of small molecules by Pseudomonas aeruginosa The Journal of Biological Chemistry, 288, (17), pp. 12042-12053. (doi:10.1074/jbc.M113.463570). (PMID:23467408).

Record type: Article

Abstract

Because small molecules enter Gram-negative bacteria via outer membrane (OM) channels, understanding OM transport is essential for the rational design of improved and new antibiotics. In the human pathogen Pseudomonas aeruginosa, most small molecules are taken up by outer membrane carboxylate channel (Occ) proteins, which can be divided into two distinct subfamilies, OccD and OccK. Here we characterize substrate transport mediated by Occ proteins belonging to both subfamilies. Based on the determination of the OccK2-glucuronate co-crystal structure, we identify the channel residues that are essential for substrate transport. We further show that the pore regions of the channels are rigid in the OccK subfamily and highly dynamic in the OccD subfamily. We also demonstrate that the substrate carboxylate group interacts with central residues of the basic ladder, a row of arginine and lysine residues that leads to and away from the binding site at the channel constriction. Moreover, the importance of the basic ladder residues corresponds to their degree of conservation. Finally, we apply the generated insights by converting the archetype of the entire family, OccD1, from a basic amino acid-specific channel into a channel with a preference for negatively charged amino acids.

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More information

e-pub ahead of print date: 6 March 2013
Published date: 26 April 2013
Keywords: Antibiotics, membrane proteins, membrane transport, pseudomonas aeruginosa, x-ray crystallography, occ family, oprd, crystal structure, outer membrane channels
Organisations: Computational Systems Chemistry

Identifiers

Local EPrints ID: 356318
URI: http://eprints.soton.ac.uk/id/eprint/356318
ISSN: 0021-9258
PURE UUID: 9f6f9b6c-486f-4296-96ac-4ad3793a8881

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Date deposited: 18 Sep 2013 16:10
Last modified: 18 Jul 2017 03:39

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Contributors

Author: E. Eren
Author: J. Parkin
Author: A. Adelanwa
Author: B. Cheneke
Author: L. Movileanu
Author: S. Khalid
Author: B. van den Berg

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