Interaction Energy Based Protein Structure Networks

Vijayabaskar, M.; Vishveshwara, Saraswathi

doi:10.1016/j.bpj.2010.08.079

Cited by 202 publications

(254 citation statements)

References 51 publications

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“…the number of links that a node has) having a Poisson-like nature (Greene and Higman 2003). Other graph theoretic properties of the adjacency matrix for PCNs have been studied in detail (Vendruscolo et al 2001;Vendruscolo et al 2002;Vishveshwara et al 2002;del Sol et al 2006a, b;Bagler and Sinha 2007;Vishveshwara et al 2009;Vijayabaskar and Vishveshwara 2010;Vendruscolo 2011). For instance, it has been shown that the shortest path lengths in the network and residue fluctuations are highly correlated (Atilgan et al 2004).…”

Section: Introductionmentioning

confidence: 96%

Analysis of core–periphery organization in protein contact networks reveals groups of structurally and functionally critical residues

Emerson

Sinha

2015

J Biosci

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The representation of proteins as networks of interacting amino acids, referred to as protein contact networks (PCN), and their subsequent analyses using graph theoretic tools, can provide novel insights into the key functional roles of specific groups of residues. We have characterized the networks corresponding to the native states of 66 proteins (belonging to different families) in terms of their core-periphery organization. The resulting hierarchical classification of the amino acid constituents of a protein arranges the residues into successive layers - having higher core order - with increasing connection density, ranging from a sparsely linked periphery to a densely intra-connected core (distinct from the earlier concept of protein core defined in terms of the three-dimensional geometry of the native state, which has least solvent accessibility). Our results show that residues in the inner cores are more conserved than those at the periphery. Underlining the functional importance of the network core, we see that the receptor sites for known ligand molecules of most proteins occur in the innermost core. Furthermore, the association of residues with structural pockets and cavities in binding or active sites increases with the core order. From mutation sensitivity analysis, we show that the probability of deleterious or intolerant mutations also increases with the core order. We also show that stabilization centre residues are in the innermost cores, suggesting that the network core is critically important in maintaining the structural stability of the protein. A publicly available Web resource for performing core-periphery analysis of any protein whose native state is known has been made available by us at http://www.imsc.res.in/ ~sitabhra/proteinKcore/index.html.

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Section: Introductionmentioning

confidence: 96%

Analysis of core–periphery organization in protein contact networks reveals groups of structurally and functionally critical residues

Emerson

Sinha

2015

J Biosci

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“…16 The nature of the subsequent ligand-induced intramolecular signaling process, however, remains a matter of debate, although various proposals of signaling pathways exist. [30][31][32][33][34][35][36][37][38] To facilitate a dynamic perspective of the allosteric mechanism, recently Buchli et al 45 presented a time-resolved study of the transition from the free to the bound state of PDZ2 triggered by a molecular photoswitch. [46][47][48][49][50][51] By covalently linking an azobenzene photoswitch across the binding groove and using a femtosecond laser pulse that affects the cis → trans photoisomerization of azobenzene, they were able to initiate a conformational change similar to the free-bound transition.…”

Section: Introductionmentioning

confidence: 99%

Long-Range Conformational Transition of a Photoswitchable Allosteric Protein: Molecular Dynamics Simulation Study

et al. 2014

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A local perturbation of a protein may lead to functional changes at some distal site. An example is the PDZ2 domain of human tyrosine phosphatase 1E which shows an allosteric transition upon binding to a peptide ligand. Recently Buchli et al. presented a time-resolved study of this transition by covalently linking an azobenzene photoswitch across the binding groove and using a femtosecond laser pulse that triggers the cis-trans photoisomerization of azobenzene. To aid the interpretation of these experiments, in this work seven microsecond runs of all-atom molecular dynamics simulations each for the wild-type PDZ2 in the ligandbound and -free state, as well as the photoswitchable protein (PDZ2S) in the cis and the trans state of the photoswitch, in explicit water. First the theoretical model is validated by recalculating the available NMR data from the simulations. By comparing the results for PDZ2 and PDZ2S, it is analyzed to what extent the photoswitch indeed mimics the free-bound transition. A detailed description of the conformational rearrangement following the cis-trans photoisomerization of PDZ2S reveals a series of photoinduced structural changes, that propagate from the anchor residues of the photoswitch via intermediate secondary structure segments to the C-terminus of PDZ2S. The changes of the conformational distribution of the C-terminal region is considered as the distal response of the isolated allosteric protein. October 9, 2014 * To whom correspondence should be addressed 1 Abstract A local perturbation of a protein may lead to functional changes at some distal site. An example is the PDZ2 domain of human tyrosine phosphatase 1E which shows an allosteric transition upon binding to a peptide ligand. Recently Buchli et al. presented a time-resolved study of this transition by covalently linking an azobenzene photoswitch across the binding groove and using a femtosecond laser pulse that triggers the cis-trans photoisomerization of azobenzene. To aid the interpretation of these experiments, in this work seven microsecond runs of all-atom molecular dynamics simulations each for the wild-type PDZ2 in the ligandbound and -free state, as well as the photoswitchable protein (PDZ2S) in the cis and the trans state of the photoswitch, in explicit water. First the theoretical model is validated by recalculating the available NMR data from the simulations. By comparing the results for PDZ2 and PDZ2S, it is analyzed to what extent the photoswitch indeed mimics the free-bound transition. A detailed description of the conformational rearrangement following the cis-trans photoisomerization of PDZ2S reveals a series of photoinduced structural changes, that propagate from the anchor residues of the photoswitch via intermediate secondary structure segments to the C-terminus of PDZ2S. The changes of the conformational distribution of the C-terminal region is considered as the distal response of the isolated allosteric protein.

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“…It has also been debated that the statistical analysis of evolutionarily coupled residues may not be true reporter of functional coupling because the evolutionary information does not include the molecular details of the interactions (31,37). Thus, a molecular thermodynamic approach that uses the perturbations in the nonbonded interactions on ligand binding would provide a more direct view of the functional energetic coupling between the protein residues (38)(39)(40).…”

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confidence: 99%

Hidden electrostatic basis of dynamic allostery in a PDZ domain

Kumawat

Chakrabarty

2017

Proc. Natl. Acad. Sci. U.S.A.

137

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Allosteric effect implies ligand binding at one site leading to structural and/or dynamical changes at a distant site. PDZ domains are classic examples of dynamic allostery without conformational changes, where distal side-chain dynamics is modulated on ligand binding and the origin has been attributed to entropic effects. In this work, we unearth the energetic basis of the observed dynamic allostery in a PDZ3 domain protein using molecular dynamics simulations. We demonstrate that electrostatic interaction provides a highly sensitive yardstick to probe the allosteric modulation in contrast to the traditionally used structure-based parameters. There is a significant population shift in the hydrogen-bonded network and salt bridges involving side chains on ligand binding. The ligand creates a local energetic perturbation that propagates in the form of dominolike changes in interresidue interaction pattern. There are significant changes in the nature of specific interactions (nonpolar/ polar) between interresidue contacts and accompanied side-chain reorientations that drive the major redistribution of energy. Interestingly, this internal redistribution and rewiring of side-chain interactions led to large cancellations resulting in small change in the overall enthalpy of the protein, thus making it difficult to detect experimentally. In contrast to the prevailing focus on the entropic or dynamic effects, we show that the internal redistribution and population shift in specific electrostatic interactions drive the allosteric modulation in the PDZ3 domain protein.A llosteric regulation of proteins plays a key role in physiological cell functions, biochemical and signal transduction pathways, and drug discovery (1-3). It has remained a challenge to understand how the thermodynamic perturbation caused by ligand binding at one site would propagate and modulate the structure and dynamics of distal regions of proteins. The prevailing models of structure-based allostery (4, 5) do not apply to the more recent examples of allostery without conformational change such as PDZ domain (6), CAP dimer (7), and met repressor (8). These examples have triggered the concept of dynamic allostery, where the side-chain dynamics is modulated on ligand binding and the origin has often been attributed to changes in the conformational entropy (9, 10). The modern view of allostery invokes a thermodynamic picture, where a population shift among preexisting conformational states occurs on binding the allosteric effector (11-13). It has also been suggested in the context of allostery without conformational change that "not observed does not imply that it is not there" (10) because crystallographic techniques may not resolve the relatively minor population shifts. An interesting idea has emerged that all proteins might be allosteric in nature (14).PDZ domain has been a classic model system to study single domain allostery without major structural changes (9, 15, 16) (Fig. 1A). PDZ domains are evolutionary conserved proteinprotein interaction module...

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Interaction Energy Based Protein Structure Networks

Cited by 202 publications

References 51 publications

Analysis of core–periphery organization in protein contact networks reveals groups of structurally and functionally critical residues

Analysis of core–periphery organization in protein contact networks reveals groups of structurally and functionally critical residues

Long-Range Conformational Transition of a Photoswitchable Allosteric Protein: Molecular Dynamics Simulation Study

Hidden electrostatic basis of dynamic allostery in a PDZ domain

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