Accepted name: 2-methyl-6-phytyl-1,4-hydroquinone methyltransferase
Reaction: (1) S-adenosyl-L-methionine + 2-methyl-6-phytylbenzene-1,4-diol = S-adenosyl-L-homocysteine + 2,3-dimethyl-6-phytylbenzene-1,4-diol
(2) S-adenosyl-L-methionine + 2-methyl-6-all-trans-nonaprenylbenzene-1,4-diol = S-adenosyl-L-homocysteine + plastoquinol
(3) S-adenosyl-L-methionine + 6-geranylgeranyl-2-methylbenzene-1,4-diol = S-adenosyl-L-homocysteine + 6-geranylgeranyl-2,3-dimethylbenzene-1,4-diol
Other name(s): VTE3 (gene name); 2-methyl-6-solanyl-1,4-hydroquinone methyltransferase; MPBQ/MSBQ methyltransferase; MPBQ/MSBQ MT
Systematic name: S-adenosyl-L-methionine:2-methyl-6-phytyl-1,4-benzoquinol C-3-methyltransferase
Comments: Involved in the biosynthesis of plastoquinol, as well as vitamin E (tocopherols and tocotrienols).
1.  Shintani, D.K., Cheng, Z. and DellaPenna, D. The role of 2-methyl-6-phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803. FEBS Lett. 511 (2002) 1–5. [PMID: 11821038]
2.  Cheng, Z., Sattler, S., Maeda, H., Sakuragi, Y., Bryant, D.A. and DellaPenna, D. Highly divergent methyltransferases catalyze a conserved reaction in tocopherol and plastoquinone synthesis in cyanobacteria and photosynthetic eukaryotes. Plant Cell 15 (2003) 2343–2356. [PMID: 14508009]
3.  Van Eenennaam, A.L., Lincoln, K., Durrett, T.P., Valentin, H.E., Shewmaker, C.K., Thorne, G.M., Jiang, J., Baszis, S.R., Levering, C.K., Aasen, E.D., Hao, M., Stein, J.C., Norris, S.R. and Last, R.L. Engineering vitamin E content: from Arabidopsis mutant to soy oil. Plant Cell 15 (2003) 3007–3019. [PMID: 14630966]
[EC created 2014]
Accepted name: homogentisate solanesyltransferase
Reaction: all-trans-nonaprenyl diphosphate + homogentisate = diphosphate + 2-methyl-6-all-trans-nonaprenylbenzene-1,4-diol + CO2
Glossary: 2-methyl-6-all-trans-nonaprenylbenzene-1,4-diol = 2-methyl-6-solanesylbenzene-1,4-diol = MSBQ
Other name(s): HST; PDS2 (gene name)
Systematic name: all-trans-nonaprenyl-diphosphate:homogentisate nonaprenyltransferase
Comments: Requires Mg2+ for activity. Part of the biosynthesis pathway of plastoquinol-9. The enzymes purified from the plant Arabidopsis thaliana and the alga Chlamydomonas reinhardtii are also active in vitro with unsaturated C10 to C20 prenyl diphosphates, producing main products that are not decarboxylated [2].
1.  Sadre, R., Gruber, J. and Frentzen, M. Characterization of homogentisate prenyltransferases involved in plastoquinone-9 and tocochromanol biosynthesis. FEBS Lett. 580 (2006) 5357–5362. [PMID: 16989822]
2.  Sadre, R., Frentzen, M., Saeed, M. and Hawkes, T. Catalytic reactions of the homogentisate prenyl transferase involved in plastoquinone-9 biosynthesis. J. Biol. Chem. 285 (2010) 18191–18198. [PMID: 20400515]
[EC created 2014]