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Structures of the Ultra-High-Affinity Protein–Protein Complexes of Pyocins S2 and AP41 and Their Cognate Immunity Proteins from Pseudomonas aeruginosa

DOI: 10.1016/j.jmb.2015.07.014 DOI Help
PMID: 26215615 PMID Help

Authors: Amar Joshi (University of Oxford) , Rhys Grinter (University of Glasgow) , Inokentijs Josts (University of Glasgow) , Sabrina Chen (University of Oxford) , Justyna Wojdyla (University of Oxford) , Edward D. Lowe (University of Oxford) , Renata Kaminska (University of Oxford) , Connor Sharp (University of Oxford) , Laura Mccaughey (University of Glasgow) , Aleksander Roszak (University of Glasgow) , Richard J. Cogdell (University of Glasgow) , Olwyn Byron (University of Glasgow) , Daniel Walker (University of Glasgow) , Colin Kleanthous (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Molecular Biology , VOL 427 (17) , PAGES 2852 - 2866

State: Published (Approved)
Published: August 2015
Diamond Proposal Number(s): 9306

Open Access Open Access

Abstract: How ultra-high-affinity protein protein interactions retain high specificity is still poorly understood. The interaction between colicin DNase domains and their inhibitory immunity (Im) proteins is an ultra-high-affinity interaction that is essential for the neutralisation of endogenous DNase catalytic activity and for protection against exogenous DNase bacteriocins. The colicin DNase-Im interaction is a model system for the study of high-affinity protein protein interactions. However, despite the fact that closely related colicin-like bacteriocins are widely produced by Gram-negative bacteria, this interaction has only been studied using colicins from Escherichia coli. In this work, we present the first crystal structures of two pyocin DNase-Im complexes from Pseudomonas aeruginosa, pyocin S2 DNase-ImS2 and pyocin AP41 DNase-ImAP41. These structures represent divergent DNase Im subfamilies and are important in extending our understanding of protein protein interactions for this important class of high-affinity protein complex. A key finding of this work is that mutations within the immunity protein binding energy hotspot, helix III, are tolerated by complementary substitutions at the DNase Immunity protein binding interface. Im helix III is strictly conserved in colicins where an Asp forms polar interactions with the DNase backbone. ImAP41 contains an Asp-to-Gly substitution in helix III and our structures show the role of a co-evolved substitution where Pro in DNase loop 4 occupies the volume vacated and removes the unfulfilled hydrogen bond. We observe the co-evolved mutations in other DNase Immunity pairs that appear to underpin the split of this family into two distinct groups. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (

Journal Keywords: Bacteriocin; P Aeruginosa.; Pyocin S2; Pyocin Ap41; Immunity Protein

Subject Areas: Biology and Bio-materials, Medicine

Instruments: I02-Macromolecular Crystallography , I03-Macromolecular Crystallography , I04-Macromolecular Crystallography