Can disorder in protein structure still yield ordered functional interactions?

(Stephen Matheson) #1

Well, okay, we already knew the answer to that. (It’s yes.) The broad roles played by intrinsically disordered proteins (and regions of proteins) have been known for a long time but are just recently being investigated in detail. This has been discussed previously on the forum (here, for example). These kinds of interactions undermine at least one main argument commonly advanced by anti-evolution writers who identify with ID.

Now a brand-new paper in Nature is going much further, identifying a specific and tight association between two proteins, both of which are intrinsically disordered. They propose that this is an under-appreciated mechanism of protein-protein interaction and provide evidence for that claim with data suggesting that the mechanism is likely to occur much more widely than is shown by their specific example. I pasted the abstract below. Be in touch if you would like a copy.

Molecular communication in biology is mediated by protein interactions. According to the current paradigm, the specificity and affinity required for these interactions are encoded in the precise complementarity of binding interfaces. Even proteins that are disordered under physiological conditions or that contain large unstructured regions commonly interact with well-structured binding sites on other biomolecules. Here we demonstrate the existence of an unexpected interaction mechanism: the two intrinsically disordered human proteins histone H1 and its nuclear chaperone prothymosin-α associate in a complex with picomolar affinity, but fully retain their structural disorder, long-range flexibility and highly dynamic character. On the basis of closely integrated experiments and molecular simulations, we show that the interaction can be explained by the large opposite net charge of the two proteins, without requiring defined binding sites or interactions between specific individual residues. Proteome-wide sequence analysis suggests that this interaction mechanism may be abundant in eukaryotes.

(system) #2

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