From: Panchenko, Anna (NIH/NLM/NCBI) [E]
Sent: Monday, March 09, 2009 10:41 AM
To: NLM/NCBI List ncbi-seminar
Subject: special seminar, March 9-th, 3pm

Special seminar on March 9-th at 3pm in the 8-th floor conference room
of Bldg 38A.

Speaker: Igor Berezovsky, University of Bergen, Norway

>From The Polymer Nature Of Proteins To The Evolution Of Protein Function

 
Polymer nature of polypeptide chain has been establishing restrictions
on shape and size of primordial proteins. Prebiotic world, therefore,
could give rise to a number of circular peptides of characteristic size
stabilized by the end-to-end contacts, and possessing one or few
chemically active residues. The latter could be an origin of functional
residues, combinations of which constitute functional sites and perform
multi-step enzymatic reactions in modern proteins. Structural analysis
of globular proteins reveals a basic building block: returns of the
polypeptide chain of preferential size (25-35 residues) stabilized by
van der Waals locks at their ends, having one or few functional residues
that are able to carry out elementary chemical transformations. These
elementary functional loops (EFL) are descendants of primitive
primordial loop-like proteins. In contemporary protein domains EFLs
bring the functional residues together forming an active site catalyzing
complex biochemical reactions. We developed a procedure to derive
prototypes of EFLs characterized by their sequence, structure, and
functional signature. Analyzing proteins of the most ancient archaeal
domain, we exploring evolution of functions as combination of EFLs.
Derived prototypes are utilized for identifying connections between
enzymatic functions by decomposing them into sets of elementary ones.