Protein assemblies with palindromic structure motifs

Citation:

Pinotsis N, Wilmanns M. Protein assemblies with palindromic structure motifs. Cell Mol Life Sci. 2008;65:2953-6.

Abstract:

Symmetric DNA sequence motifs allow the formation of palindromic protein/DNA complexes. Although symmetric protein sequence motifs are less common, recent structural discoveries have unraveled a few protein/protein complexes with palindromic symmetry. Remarkably, symmetric protein/protein complexes can be generated either by adjacent or remote sequence motifs, which may be repeated or inverted. This contribution reflects and comments on recent findings of palindromic protein/protein complexes.

Notes:

Pinotsis, NWilmanns, MengResearch Support, Non-U.S. Gov'tReviewSwitzerlandCell Mol Life Sci. 2008 Oct;65(19):2953-6. doi: 10.1007/s00018-008-8265-1.

Contact Details

Biochemistry, Chemistry Department
National and Kapodistrian University of Athens
(+30) 210-727 4493
Zografou
Athens, ZipCode 157 84

Recent Publications

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Ma S, Mykhaylyk V, Bowler MW, Pinotsis N, Kozielski F. High-Confidence Placement of Fragments into Electron Density Using Anomalous Diffraction-A Case Study Using Hits Targeting SARS-CoV-2 Non-Structural Protein 1. Int J Mol Sci. 2023;24.Abstract

The identification of multiple simultaneous orientations of small molecule inhibitors binding to a protein target is a common challenge. It has recently been reported that the conformational heterogeneity of ligands is widely underreported in the Protein Data Bank, which is likely to impede optimal exploitation to improve affinity of these ligands. Significantly less is even known about multiple binding orientations for fragments (<300 Da), although this information would be essential for subsequent fragment optimisation using growing, linking or merging and rational structure-based design. Here, we use recently reported fragment hits for the SARS-CoV-2 non-structural protein 1 (nsp1) N-terminal domain to propose a general procedure for unambiguously identifying binding orientations of 2-dimensional fragments containing either sulphur or chloro substituents within the wavelength range of most tunable beamlines. By measuring datasets at two energies, using a tunable beamline operating in vacuum and optimised for data collection at very low X-ray energies, we show that the anomalous signal can be used to identify multiple orientations in small fragments containing sulphur and/or chloro substituents or to verify recently reported conformations. Although in this specific case we identified the positions of sulphur and chlorine in fragments bound to their protein target, we are confident that this work can be further expanded to additional atoms or ions which often occur in fragments. Finally, our improvements in the understanding of binding orientations will also serve to improve the rational optimisation of SARS-CoV-2 nsp1 fragment hits.

Le Huray KIP, Bunney TD, Pinotsis N, Kalli AC, Katan M. Characterization of the membrane interactions of phospholipase Cgamma reveals key features of the active enzyme. Sci AdvSci Adv. 2022;8:eabp9688.Abstract

PLCgamma enzymes are autoinhibited in resting cells and form key components of intracellular signaling that are also linked to disease development. Insights into physiological and aberrant activation of PLCgamma require understanding of an active, membrane-bound form, which can hydrolyze inositol-lipid substrates. Here, we demonstrate that PLCgamma1 cannot bind membranes unless the autoinhibition is disrupted. Through extensive molecular dynamics simulations and experimental evidence, we characterize membrane binding by the catalytic core domains and reveal previously unknown sites of lipid interaction. The identified sites act in synergy, overlap with autoinhibitory interfaces, and are shown to be critical for the phospholipase activity in cells. This work provides direct evidence that PLCgamma1 is inhibited through obstruction of its membrane-binding surfaces by the regulatory region and that activation must shift PLCgamma1 to a conformation competent for membrane binding. Knowledge of the critical sites of membrane interaction extends the mechanistic framework for activation, dysregulation, and therapeutic intervention.

Nikos Pinotsis

Associate Professor, Chemistry