Molecular architecture and structural basis of allosteric regulation of eukaryotic phosphofructokinases.

Eukaryotic ATP-dependent 6-phosphofructokinases (Pfks) differ from their bacterial counterparts in a much more complex structural organization and allosteric regulation. Pichia pastoris Pfk (PpPfk) is, with similar to 1 MDa, the most complex and probably largest eukaryotic Pfk. We have determined the crystal structure of full-length PpPfk to 3.05 angstrom resolution in the T state. PpPfk forms a (alpha beta gamma)(4) dodecamer of D(2) symmetry with dimensions of 161 x 157 x 233 angstrom mainly via interactions of the alpha chains. The N-terminal domains of the alpha and beta chains have folds that are distantly related to glyoxalase I, but the active sites are no longer functional. Interestingly, these domains located at the 2 distal ends of this protein along the long 2-fold axis form a (alpha beta)(2) dimer as does the core Pfk domains; however, the domains are swapped across the tetramerization interface. In PpPfk, the unique gamma subunit participates in oligomerization of the alpha beta chains. This modulator protein was acquired from an ancient S-adenosylmethionine-dependent methyltransferase. The identification of novel ATP binding sites, which do not correspond to the bacterial catalytic or effector binding sites, point to marked structural and functional differences between bacterial and eukaryotic Pfks.-Strater, N., Marek, S., Kuettner, E. B., Kloos, M., Keim, A., Bruser, A., Kirchberger, J., Schoneberg, T. Molecular architecture and structural basis of allosteric regulation of eukaryotic phosphofructokinases. FASEB J. 25, 89-98 (2011). www.fasebj.org