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Buenos Aires, Argentina

Ferreiro D.U.,Protein Physiology Laboratory | Komives E.A.,University of California at San Diego | Wolynes P.G.,Rice University
Quarterly Reviews of Biophysics | Year: 2014

Biomolecules are the prime information processing elements of living matter. Most of these inanimate systems are polymers that compute their own structures and dynamics using as input seemingly random character strings of their sequence, following which they coalesce and perform integrated cellular functions. In large computational systems with finite interaction-codes, the appearance of conflicting goals is inevitable. Simple conflicting forces can lead to quite complex structures and behaviors, leading to the concept of frustration in condensed matter. We present here some basic ideas about frustration in biomolecules and how the frustration concept leads to a better appreciation of many aspects of the architecture of biomolecules, and especially how biomolecular structure connects to function by means of localized frustration. These ideas are simultaneously both seductively simple and perilously subtle to grasp completely. The energy landscape theory of protein folding provides a framework for quantifying frustration in large systems and has been implemented at many levels of description. We first review the notion of frustration from the areas of abstract logic and its uses in simple condensed matter systems. We discuss then how the frustration concept applies specifically to heteropolymers, testing folding landscape theory in computer simulations of protein models and in experimentally accessible systems. Studying the aspects of frustration averaged over many proteins provides ways to infer energy functions useful for reliable structure prediction. We discuss how frustration affects folding mechanisms. We review here how the biological functions of proteins are related to subtle local physical frustration effects and how frustration influences the appearance of metastable states, the nature of binding processes, catalysis and allosteric transitions. In this review, we also emphasize that frustration, far from being always a bad thing, is an essential feature of biomolecules that allows dynamics to be harnessed for function. In this way, we hope to illustrate how Frustration is a fundamental concept in molecular biology. Copyright © 2014 Cambridge University Press. Source

Chemes L.B.,CONICET | Glavina J.,Protein Physiology Laboratory | Faivovich J.,CONICET | Faivovich J.,University of Buenos Aires | And 2 more authors.
Journal of Molecular Biology | Year: 2012

Many protein functions can be traced to linear sequence motifs of less than five residues, which are often found within intrinsically disordered domains. In spite of their prevalence, their role in protein evolution is only beginning to be understood. The study of papillomaviruses has provided many insights on the evolution of protein structure and function. We have chosen the papillomavirus E7 oncoprotein as a model system for the evolution of functional linear motifs. The multiple functions of E7 proteins from paradigmatic papillomavirus types can be explained to a large extent in terms of five linear motifs within the intrinsically disordered N-terminal domain and two linear motifs within the globular homodimeric C-terminal domain. We examined the motif inventory of E7 proteins from over 200 known papillomavirus types and found that the motifs reported for paradigmatic papillomavirus types are absent from many uncharacterized E7 proteins. Several motif pairs occur more often than expected, suggesting that linear motifs may evolve and function in a cooperative manner. The E7 linear motifs have appeared or disappeared multiple times during papillomavirus evolution, confirming the evolutionary plasticity of short functional sequences. Four of the motifs appeared several times during papillomavirus evolution, providing direct evidence for convergent evolution. Interestingly, the evolution pattern of a motif is independent of its location in a globular or disordered domain. The correlation between the presence of some motifs and virus host specificity and tissue tropism suggests that linear motifs play a role in the adaptive evolution of papillomaviruses. © 2012 Elsevier Ltd. All rights reserved. Source

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