Expression, characterization, and crystallization of the pyrophosphate-dependent phosphofructo-1-kinase of Borrelia burgdorferi

The two genes for the putative pyrophosphate-dependent phosphofructokinases (PPi-PFKs) of Borrelia burgdorferi were cloned by PGR and expressed in Escherichia coli, and their protein products were purified to near homogeneity. The larger of the two gene products, a 62-kDa protein, is an active PPi-PFK and exists in solution as a dimer. It has apparent K-m values for fructose 6-P and PPi of 109 and 15 mu M, respectively, and a pH optimum of 6.4 to 7.2. The 62-kDa protein was crystallized and subjected to preliminary diffraction analysis. The smaller gene product, a 48-kDa protein, exists in solution as a higher polymer and shows no ATP- or PPi-dependent activity, despite having a secondary structure as estimated by circular dichroism that is not significantly different from that of other PFKs. (C) 1999 Academic Press.