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Posted: Jan 11, 2013
Protein recognition and disorder: a debate
(Nanowerk News) The extent to which three-dimensional structure is required for protein recognition and function is an area of vigorous debate with clear implications for protein engineering. Two differing viewpoints have been put forward in two articles published in F1000 Biology Reports today.
In structuring their arguments, the authors were encouraged to consider the opposing viewpoint,
examine the points put forward and critique them in their own articles. This novel collaborative
approach has given rise to a considered exchange of ideas and may consequently stimulate further
research in the field.
In contrast, Joël Janin (Université Paris-Sud) and Michael J.E. Sternberg (Imperial College, London), in
their article “Protein flexibility, not disorder, is intrinsic to molecular recognition”, argue that a protein’s function in the real world environment
of the body’s cells is dependent on the structure of that protein, and that protein recognition requires
regions of complementary structure binding to each other. Janin and Sternberg also note that many
proteins seem to be disordered in the test tube but are in fact proteins waiting for partners (PWPs),
which then adopt fully ordered structures in the presence of other components of the cell required to
perform a function.
To counter the argument put forward by Janin and Sternberg, Dunker and Uversky conclude that the
major difference between ordinary proteins and IDPs is that the former fold first and then bind to their
partners while that latter remain disordered until they bind their partners. Furthermore, some IDPs can
be much more dynamic than just “waiting for a partner”, with the ability to switch from one partner to
another and change structures while changing the partner.
Commenting on the two articles, Richard Henderson, MRC Laboratory of Molecular Biology, Cambridge
said: “Both articles are by leaders who have given a great deal of thought to the function of proteins
that appear to be intrinsically unfolded. Their different emphases will no doubt stimulate experiments
as well as debate in the Structural Biology community. Time will tell us whether one or both models
reflect how nature uses these structures.”