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Chlamydia protein Pgp3 studied at high resolution in a new crystal form

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Title: Chlamydia protein Pgp3 studied at high resolution in a new crystal form
Authors: Khurshid, S
Govada, L
Wills, G
McClure, M
Helliwell, J
Chayen, N
Item Type: Journal Article
Abstract: The protein Pgp3 is implicated in the sexually transmitted disease chlamydia and comprises an extended complex arrangement of a C terminal domain (CTD) and an N terminal domain (NTD), each linked by a triple helix coiled coil (THCC). We report the X-ray crystal structure of Pgp3 from a LGV1 strain at the highest X-ray diffraction resolution obtained to date for the full protein. The protein was crystallised using a high KBr salt concentration, which resulted in a new crystal form with relatively low solvent content diffracting to a resolution of 1.98 Å. We describe the 3D structure of this new crystal form, compare it with other crystal forms, describe the KBr salt binding sites and the relevance to chlamydia isolates from around the globe. The crystal packing is apparently driven by the CTDs. Since the three fold axes of the THCC and NTD are not collinear with a CTD’s three fold axis this naturally leads to a disorder in the THCC and the portion of the NTD not directly interacting with the CTD via crystal packing. The key avenue to resolve these oddities of the crystal structure analysis was a complete new analysis in space group P1 and determining the space group as P212121. This space group assignment was the one originally determined from the diffraction pattern but perhaps complicated by a translational non crystallographic symmetry. We found this crystal structure of a three domain multi macromolecular complex, with two misaligned three fold axes, a unique challenge, something not encountered before. A specific intermolecular interaction, possibly of functional significance in receptor binding in chlamydia, we suggest might allow design of a new chemotherapeutic agent against chlamydia.
Issue Date: 1-Jul-2018
Date of Acceptance: 22-May-2018
URI: http://hdl.handle.net/10044/1/59913
DOI: https://dx.doi.org/10.1107/S2052252518007637
ISSN: 2052-2525
Publisher: International Union of Crystallography
Start Page: 439
End Page: 448
Journal / Book Title: IUCrJ
Volume: 5
Issue: 4
Copyright Statement: © 2018 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY https://creativecommons.org/licenses/by/2.0/uk/legalcode) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Science and Technology Facilities Council (STFC)
Funder's Grant Number: EP/G027005/1
Keywords: Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Materials Science, Multidisciplinary
Materials Science
chlamydia protein
crystal form
protein structure
X-ray crystallography
structural biology
sexually transmitted diseases
Publication Status: Published
Online Publication Date: 2018-06-07
Appears in Collections:Department of Medicine (up to 2019)
Department of Medicine (up to 2019)
Faculty of Natural Sciences