Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
GroEL is a bacterial chaperonin of 14 identical subunits required to help fold newly synthesized proteins. The crystal structure of GroEL with ATP gamma S bound to each subunit shows that ATP binds to a novel pocket, whose primary sequence is highly conserved among chaperonins. Interaction of Mg2+ and ATP involves phosphate oxygens of the alpha-, beta- and gamma-phosphates, which is unique for known structures of nucleotide-binding proteins. Although bound ATP induces modest conformational shifts in the equatorial domain, the stereochemistry that functionally coordinates GroEL's affinity for nucleotides, polypeptide, and GroES remains uncertain.