The separate roles of plant cis and trans prenyl transferases in cis‐1,4‐polyisoprene biosynthesis

In plants, the elongation of cis-1,4-polyisoprene (natural rubber, M(r) > 10(6) requires a small transallylic diphosphate (< or = C20) initiator. The trans-allylic diphosphates are hydrophilic cytosolic compounds, whereas cis-1,4-polyisoprene is hydrophobic and compartmentalised in subcellular rubber particles. In this paper, it is demonstrated that soluble trans-prenyl transferase from latex of Hevea brasiliensis functions solely as farnesyl diphosphate synthase, and plays no direct role in cis-1,4-polyisoprene elongation. The cis-1,4-prenyl transferase is firmly associated with the H. brasiliensis rubber particle, as is also the case in other rubber-producing species Archer, B. L., Audley, B. G., Cockbain, E. G. Madhavan, S., Greenblatt, G. A., Foster, M. A. Siler, D. J. Light, D. R., Lazarus, R. A. & Dennis, M. S. (1989) J. Biol. Chem. 264, 18598-18607. Thus, it appears that plant prenyl transferases are comparable to animal enzyme systems in which trans-prenyl transferases are soluble enzymes whilst cis-prenyl transferases are membrane-bound Ericcson, J., Runquist, M., Thelin, A., Andersson, M., Chojnacki, T. & Dallner, G. (1992) J. Biol Chem. 268, 832-838.