Identification and biochemical characterization of a heteromeric cis-prenyltransferase from the thermophilic archaeon Archaeoglobus fulgidus

cis-Prenyltransferases (cPTs) form linear polyprenyl pyrophosphates, the precursors of polyprenyl or dolichyl phosphates that are essential for cell function in all living organisms. Polyprenyl phosphate serves as a sugar carrier for peptidoglycan cell wall synthesis in bacteria, a role that dolichyl phosphate performs analogously for protein glycosylation in eukaryotes and archaea. Bacterial cPTs are characterized by their homodimeric structure, while cPTs from eukaryotes usually require two distantly homologous subunits for enzymatic activity. This study identifies the subunits of heteromeric cPT, Af1219 and Af0707, from a thermophilic sulphur-reducing archaeon, Archaeoglobus fulgidus. Both subunits are indispensable for cPT activity, and their protein-protein interactions were demonstrated by a pulldown assay. Gel filtration chromatography and chemical cross-linking experiments suggest that Af1219 and Af0707 likely form a heterotetramer complex. Although this expected subunit composition agrees with a reported heterotetrameric structure of human hCIT/NgBR cPT complex, the similarity of the quaternary structures is likely a result of convergent evolution.