title: Dimerization determines substrate specificity of a bacterial prenyltransferase.
abstract: We have identified the native dimer interface of heptaprenylglyceryl phosphate synthase PcrB from the bacterium Bacillus subtilis and analyzed the significance of oligomer formation for stability and catalytic activity. Computational methods predicted two different surface regions of the PcrB protomer that could be responsible for dimer formation. These bona fide interfaces were assessed both in silico and experimentally by the introduction of amino acid substitutions that led to monomerization, and by incorporation of an unnatural amino acid to allow cross-linking of the two protomers. The results showed that, in contrast to previous assumptions, PcrB uses the same interface for dimerization as the homologous geranylgeranylglyceryl phosphate synthase from Archaea. Thermal unfolding demonstrated that the monomeric proteins are only slightly less stable than wild-type PcrB. However, activity assays showed that monomerization limits the length of accepted polyprenyl pyrophosphates to three isoprene units, whereas the native PcrB substrate contains seven isoprene entities. We provide a plausible hypothesis as to how dimerization determines substrate specificity of PcrB.
authors.affiliation: Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Peterhoff
authors.forename: Hermann
authors.initials: H
authors.lastname: Zellner
authors.forename: Harald
authors.initials: H
authors.lastname: Guldan
authors.forename: Rainer
authors.initials: R
authors.lastname: Merkl
authors.forename: Reinhard
authors.initials: R
authors.lastname: Sterner
authors.forename: Patrick
authors.initials: P
authors.lastname: Babinger
mesh_terms: D019943:Amino Acid Substitution; D001412:Bacillus subtilis / Q000201:enzymology*; D004122:Dimethylallyltranstransferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D008958:Models, Molecular; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D004122:Dimethylallyltranstransferase