Identification of unknown protein function using metabolite cocktail screening.
Shumilin, I.A., Cymborowski, M., Chertihin, O., Jha, K.N., Herr, J.C., Lesley, S.A., Joachimiak, A., Minor, W.(2012) Structure 20: 1715-1725
- PubMed: 22940582 
- DOI: https://doi.org/10.1016/j.str.2012.07.016
- PubMed Abstract: 
Proteins of unknown function comprise a significant fraction of sequenced genomes. Defining the roles of these proteins is vital to understanding cellular processes. Here, we describe a method to determine a protein function based on the identification of its natural ligand(s) by the crystallographic screening of the binding of a metabolite library, followed by a focused search in the metabolic space. The method was applied to two protein families with unknown function, PF01256 and YjeF_N. The PF01256 proteins, represented by YxkO from Bacillus subtilis and the C-terminal domain of Tm0922 from Thermotoga maritima, were shown to catalyze ADP/ATP-dependent NAD(P)H-hydrate dehydratation, a previously described orphan activity. The YjeF_N proteins, represented by mouse apolipoprotein A-I binding protein and the N-terminal domain of Tm0922, were found to interact with an adenosine diphosphoribose-related substrate and likely serve as ADP-ribosyltransferases. Crystallographic screening of metabolites serves as an efficient tool in functional analyses of uncharacterized proteins.
Organizational Affiliation: 
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA. ias2n@virginia.edu