Protein structure and evolution: are they constrained globally by a principle derived from information theory?

Area of Science:

• Biophysics
• Computational Biology
• Evolutionary Biology

Background:

• Physicochemical properties of amino acids are known to influence protein structure, function, and evolution.
• Information theory principles may also impose constraints on protein structure and evolutionary trajectories.

Purpose of the Study:

• To investigate whether information theory principles, specifically a conservation principle, can explain global properties of proteins.
• To test predictions derived from information theory against the full set of proteins in the SwissProt database.

Main Methods:

• Analysis of the global properties of all proteins in SwissProt release 13-11.
• Experimental testing of predictions derived from information theory.
• Examination of the relationship between unique amino acid count, total protein length, average protein length, and the occurrence of proteins with specific unique amino acid counts.

Main Results:

• Protein collective structure exhibits properties consistent with guidance by a conservation principle.
• This principle, termed "Conservation of Information," defines global properties of systems composed of discrete components (proteins assembled from amino acids).
• Conservation of Information operates at a global level, independent of local physicochemical properties and natural selection, constraining the overall protein system.

Conclusions:

• A "Conservation of Information" principle appears to constrain the global system of proteins.
• This principle influences protein evolution at a level distinct from natural selection.
• The findings suggest a counter-intuitive but supported conclusion regarding global constraints on protein evolution.