Prenyltransferase of larval and adult M. sexta corpora allata

Prenyltransferase activity derived from the corpora allata (CA) of the lepidopteran insect, Manduca sexta, has been characterized. The coupling of allylic substrates DMAPP and GPP with the non-allylic substrate IPP was evaluated using CA homogenates of both the larval and adult stages of development. The effect of additives and inhibitors, assay conditions, and metal preference were examined. The cellular location of prenyltransferase activity was also investigated. We found subtle differences between larval and adult preparations, including metal and detergent preference, and while larval prenyltransferase activity was strictly cytosolic, prenyltransferase derived from adult CA was found in both the cytosolic and pellet fractions. Differences in kinetics as a function of development were also noted. When GPP was utilized as allylic substrate, adult prenyltransferase displayed cooperative behavior; while with DMAPP, biphasic kinetics were observed. In fifth instar larvae, prenyltransferase activity was highest on days 1–2 and reaction end products changed as a result of insect age. Taken together, these results suggest that larval and adult prenyltransferase of M. sexta have distinct enzymological properties and that the adult CA possess more than one prenyltransferase.