scholarly journals Multiple Dimerizing Motifs Modulate the Dimerization of the Syndecan Transmembrane Domains

2020 ◽  
Author(s):  
J. Chen ◽  
F. Wang ◽  
C. He ◽  
S-Z. Luo
Keyword(s):  
Protein Interactions ◽  
Self Assembly ◽  
Transmembrane Domains ◽  
Integral Membrane Proteins ◽  
Sequence Motifs ◽  
Protein Protein Interactions ◽  
Dynamics Simulations ◽  
Considerable Complexity ◽  
Shed Light ◽  
Common Sequence

AbstractSyndecans(SDCs) are a family of four members of integral membrane proteins, which play important roles in cell-cell interactions. Dimerization/oligomerization generated by transmembrane domains (TMDs) appear to crucially regulate several functional behaviors of all syndecan members. The distinct hierarchy of protein-protein interactions mediated by the syndecan TMDs may give rise to considerable complexity in the functions of syndecans. The molecular mechanism of the different dimerization tendencies in each type of SDCs remains unclear. Here, the self-assembly process of syndecan TMD homodimers and heterodimers was studied in molecular details by molecular dynamics simulations. Our computational results showed that the SDC2 forms the most stable homodimer while the SDC1 TMD dimerizes weakly, which is consistent with previous experimental results. Detailed analysis suggests that instead of the conserved dimerizing motif G8XXXG12 in all four SDCs involved in homo- and hetero-dimerization of SDCs, the G3XXXA7 motif in SDC1 competes with the interface of G8XXXG12 and thus disturbs the SDC1 involved dimerization. The SDC3 which contains a G9XXXA13 motif, however, forms a more stable dimer than SDC1, indicating the complexity of the competing effect of the GXXXA motif. As GXXXG and GXXXA are two common sequence motifs in the dimerization of helices, our results shed light on the competing effect of multiple dimerizing motifs on the dimerization of transmembrane domains.

Metallocluster transactions: dynamic protein interactions guide the biosynthesis of Fe–S clusters in bacteria

2018 ◽  
Vol 46 (6) ◽  
pp. 1593-1603 ◽  
Author(s):  
Chenkang Zheng ◽  
Patricia C. Dos Santos
Keyword(s):  
Protein Interactions ◽  
Protein Complexes ◽  
Specific Protein ◽  
Biological Synthesis ◽  
Cluster Assembly ◽  
Sequence Motifs ◽  
Protein Protein Interactions ◽  
Cysteine Desulfurase ◽  
Wide Range ◽  
Domains Of Life

Iron–sulfur (Fe–S) clusters are ubiquitous cofactors present in all domains of life. The chemistries catalyzed by these inorganic cofactors are diverse and their associated enzymes are involved in many cellular processes. Despite the wide range of structures reported for Fe–S clusters inserted into proteins, the biological synthesis of all Fe–S clusters starts with the assembly of simple units of 2Fe–2S and 4Fe–4S clusters. Several systems have been associated with the formation of Fe–S clusters in bacteria with varying phylogenetic origins and number of biosynthetic and regulatory components. All systems, however, construct Fe–S clusters through a similar biosynthetic scheme involving three main steps: (1) sulfur activation by a cysteine desulfurase, (2) cluster assembly by a scaffold protein, and (3) guided delivery of Fe–S units to either final acceptors or biosynthetic enzymes involved in the formation of complex metalloclusters. Another unifying feature on the biological formation of Fe–S clusters in bacteria is that these systems are tightly regulated by a network of protein interactions. Thus, the formation of transient protein complexes among biosynthetic components allows for the direct transfer of reactive sulfur and Fe–S intermediates preventing oxygen damage and reactions with non-physiological targets. Recent studies revealed the importance of reciprocal signature sequence motifs that enable specific protein–protein interactions and consequently guide the transactions between physiological donors and acceptors. Such findings provide insights into strategies used by bacteria to regulate the flow of reactive intermediates and provide protein barcodes to uncover yet-unidentified cellular components involved in Fe–S metabolism.

scholarly journals Molecular dynamics shows complex interplay and long-range effects of post-translational modifications in yeast protein interactions

2021 ◽  
Vol 17 (5) ◽  
pp. e1008988
Author(s):  
Nikolina ŠoŠtarić ◽  
Vera van Noort
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Protein Structures ◽  
Cellular Protein ◽  
Free Energy Calculations ◽  
Protein Protein Interactions ◽  
Post Translational Modifications ◽  
Protein Properties ◽  
Dynamics Simulations

Post-translational modifications (PTMs) play a vital, yet often overlooked role in the living cells through modulation of protein properties, such as localization and affinity towards their interactors, thereby enabling quick adaptation to changing environmental conditions. We have previously benchmarked a computational framework for the prediction of PTMs’ effects on the stability of protein-protein interactions, which has molecular dynamics simulations followed by free energy calculations at its core. In the present work, we apply this framework to publicly available data on Saccharomyces cerevisiae protein structures and PTM sites, identified in both normal and stress conditions. We predict proteome-wide effects of acetylations and phosphorylations on protein-protein interactions and find that acetylations more frequently have locally stabilizing roles in protein interactions, while the opposite is true for phosphorylations. However, the overall impact of PTMs on protein-protein interactions is more complex than a simple sum of local changes caused by the introduction of PTMs and adds to our understanding of PTM cross-talk. We further use the obtained data to calculate the conformational changes brought about by PTMs. Finally, conservation of the analyzed PTM residues in orthologues shows that some predictions for yeast proteins will be mirrored to other organisms, including human. This work, therefore, contributes to our overall understanding of the modulation of the cellular protein interaction networks in yeast and beyond.

scholarly journals Self-assembly and adsorption of cetyltrimethylammonium bromide and didodecyldimethylammonium bromide surfactants at the mica–water interface

Soft Matter ◽  
2019 ◽  
Vol 15 (41) ◽  
pp. 8402-8411 ◽  
Author(s):  
Georgia Tsagkaropoulou ◽  
Finian J. Allen ◽  
Stuart M. Clarke ◽  
Philip J. Camp
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Self Assembly ◽  
Cetyltrimethylammonium Bromide ◽  
Ionic Surfactants ◽  
Water Interface ◽  
Didodecyldimethylammonium Bromide ◽  
Dynamics Simulations ◽  
Shed Light

Molecular-dynamics simulations are used to explore bilayers formed by simple ionic surfactants at the mica–water interface, and to shed light on experimental observations.

scholarly journals Sequence conservation, domain architectures, and phylogenetic distribution of the HD-GYP type c-di-GMP phosphodiesterases

2021 ◽  
Author(s):  
Michael Y. Galperin ◽  
Shan-Ho Chou
Keyword(s):  
Protein Interactions ◽  
Regulatory Protein ◽  
Second Messenger ◽  
Distribution Patterns ◽  
Distribution Functions ◽  
Amino Acid Residues ◽  
Sequence Motifs ◽  
Protein Protein Interactions ◽  
Conserved Sequence ◽  
Common Domain

The HD-GYP domain, named after two of its conserved sequence motifs, was first described in 1999 as a specialized version of the widespread HD phosphohydrolase domain that had additional highly conserved amino acid residues. Domain associations of HD-GYP indicated its involvement in bacterial signal transduction and distribution patterns of this domain suggested that it could serve as a hydrolase of the bacterial second messenger c-di-GMP, in addition to or instead of the EAL domain. Subsequent studies confirmed the ability of various HD-GYP domains to hydrolyze c-di-GMP to linear pGpG and/or GMP. Certain HD-GYP-containing proteins hydrolyze another second messenger, cGAMP, and some HD-GYP domains participate in regulatory protein-protein interactions. The recently solved structures of HD-GYP domains from four distinct organisms clarified the mechanisms of c-di-GMP binding and metal-assisted hydrolysis. However, the HD-GYP domain is poorly represented in public domain databases, which causes certain confusion about its phylogenic distribution, functions, and domain architectures. Here, we present a refined sequence model for the HD-GYP domain and describe the roles of its most conserved residues in metal and/or substrate binding. We also calculate the numbers of HD-GYPs encoded in various genomes and list the most common domain combinations involving HD-GYP, such as the RpfG (REC-HD-GYP), Bd1817 (DUF3391-HD-GYP), and PmGH (GAF-HD-GYP) protein families. We also provide the descriptions of six HD-GYP-associated domains, including four novel integral membrane sensor domains. This work is expected to stimulate studies of diverse HD-GYP-containing proteins, their N-terminal sensor domains, and the signals to which they respond.

scholarly journals Selectivity of Protein Interactions along the Aggregation Pathway of α-Synuclein

2021 ◽  
Author(s):  
André D. G. Leitão ◽  
Paulina Rudolffi Soto ◽  
Alexandre Chappard ◽  
Akshay Bhumkar ◽  
Dominic J. B. Hunter ◽  
...  
Keyword(s):  
Single Molecule ◽  
Protein Interactions ◽  
Self Assembly ◽  
Amyloid Fibrils ◽  
Lewy Bodies ◽  
Coincidence Detection ◽  
Protein Protein Interactions ◽  
Assembly Pathway ◽  
Protein Partners ◽  
Molecular Complexity

AbstractThe aggregation of α-SYN follows a cascade of oligomeric, prefibrillar and fibrillar forms, culminating in the formation of Lewy Bodies (LB), the pathological hallmarks of Parkinson’s Disease in neurons. Whilst α-synuclein is a major contributor to LB, these dense accumulations of protein aggregates and tangles of fibrils contain over 70 different proteins. However, the potential for interactions between these proteins and the different aggregated species of α-SYN is largely unknown. We hypothesized that the proteins present in the Lewy Bodies are trapped or pulled into the aggregates in a hierarchical manner, by binding at specific stages of the aggregation of α-SYN.In this study we uncover a map of interactions of a total of 65 proteins, against different species formed by α-SYN. We measured binding to monomeric α-SYN using AlphaScreen, a sensitive nano-bead assay for detection of protein-protein interactions. To access different oligomeric species, we made use of the pathological mutants of α-SYN (A30P, G51D and A53T), which form oligomeric species with distinct properties. Finally, we used bacterially expressed recombinant α-SYN to generate amyloid fibrils and measure interactions with a pool of GFP-tagged potential partners. Binding to oligomers and fibrils was measured by two-color coincidence detection (TCCD) on a single molecule spectroscopy setup. Overall, we demonstrate that LB components are selectively recruited to specific steps in the formation of the LB, explaining their presence in the inclusions. Only a few proteins were found to interact with α-SYN monomers at detectable levels, and only a subset recognizes the oligomeric α-SYN including autophagosomal proteins. We therefore propose a new model for the formation of Lewy Bodies, where selectivity of protein partners at different steps drives the arrangement of these structures, uncovering new ways to modulate aggregation.Significance StatementThe molecular complexity of the Lewy Bodies has been a major hindrance to a bottom-up reconstruction of these inclusions, protein by protein. This work presents an extensive dataset of protein-protein interactions, showing that despite its small size and absence of structure, α-SYN binds to specific partners in the LB, and that there is a clear selectivity of interactions between the different α-SYN species along the self-assembly pathway. We use single-molecule methods to deconvolute number and size of the co-aggregates, to gain detailed information about the mechanisms of interaction. These observations constitute the basis for the elaboration of a global interactome of α-SYN.

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