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. 2020 Oct 21;5(5):e00675-20. doi: 10.1128/mSphere.00675-20

FIG 1.

FIG 1

IPP and terpenoid-quinone biosynthesis in E. longa and its phototrophic relative E. gracilis. (a) Schematic comparison of the localization of enzymes (see the key below the E. longa “cell”). A question mark indicates unknown molecular identity of some of the enzymes (whose subcellular localization suggested by the figure must be considered tentative). Abbreviations for IPP synthesis: ACAT, acetyl-CoA acetyltransferase; CDP-ME, 4-(cytidine 5′-diphospho)-2-C-methyl-d-erythritol; CDP-MEP, 2-phospho-CDP-ME; CMK, CDP-ME kinase; CMS, CDP-ME synthase; DMAPP, dimethylallyl diphosphate; DXP, 1-deoxy-d-xylulose 5-phosphate; DXR, DXP reductase; DXS, DXP synthase; FPP, farnesyl diphosphate synthase; GGPS, geranylgeranyl-diphosphate synthase; HDR, HMB-PP reductase; HDS, HMB-PP synthase; HMB-PP, 4-hydroxy-3-methylbut-2-en-1-yl diphosphate; HMG-CoA, 3-hydroxy-3-methylglutaryl-CoA; HMGCR, HMG-CoA reductase; HMGCS, HMG-CoA synthase; IDI, isopentenyl-diphosphate delta-isomerase; MCS, MEcPP synthase; MDD, mevalonate-diphosphate decarboxylase; MEcPP, 2-C-methyl-d-erythritol 2;4-cyclodiphosphate; MEP, 2-C-methyl-d-erythritol 4-phosphate; MVK, mevalonate kinase; PMVK, phosphomevalonate kinase; PPS, unspecified polyprenyl-diphosphate synthase; ?, unclear substrate or unknown enzyme. Abbreviations for terpenoid-quinone synthesis: 4HPP, 4-hydroxyphenylpyruvate; HPD, hydroxyphenylpyruvate dioxygenase; HPT, homogentisate phytyltransferase; LTO1, PhQ-reducing oxidoreductase; MMT, MPBQ/MPSQ methyltransferase; TC, tocopherol cyclase; TOMT, tocopherol-O-methyltransferase; VTE5, phytyl kinase; VTE6, phytyl-phosphate kinase. (b) MS/MS spectrum record of E. longa α-tocopherol and the proposed fragmentation pattern in positive ionization mode (inset). Monoisotopic masses of particular fragments were obtained by simulation in the Xcalibur software. (c) Semiquantitative comparison of tocopherol species in E. longa, heterotrophically (dark) grown E. gracilis, and autotrophically grown E. gracilis. Peak area is shown in arbitrary units (A.U.) (see the legend to Fig. 2). (d and e) MS/MS spectrum record of E. longa 5-hydroxyphylloquinone and the proposed fragmentation pattern in positive ionization mode (inset); semiquantitative comparison of 5-hydroxyphylloquinone in E. longa, heterotrophically (dark) grown E. gracilis, and autotrophically grown E. gracilis.