Insight into C₃₅ terpene Biosyntheses by Nonpathogenic Mycobacterium Species: Functional Analyses of Three Z‐Prenyltransferases and Identification of Dehydroheptaprenylcyclines

Abstract

Nonpathogenic Mycobacterium species produce rare cyclic C(35) terpenes that are biosynthesized by cyclization of Z-type C(35) polyprenyl diphosphate. To provide deeper insight into the biosynthesis of C(35) terpenes, we carried out functional analyses of three Z-prenyltransferase homologues in M. vanbaalenii identified by genomic analysis. Mvan_3822, a novel bifunctional Z-prenyltransferase, biosynthesizes C(35)-heptaprenyl diphosphate as a main product from (E,E)-farnesyl diphosphate (E,E-FPP) and (E,E,E)-geranylgeranyl diphosphate (E,E,E-GGPP), but produces a C(50)-decaprenyl diphosphate from geranyl diphosphate. Mvan_1705 is a novel Z,E,E-GGPP synthase. In addition, novel cyclic C(35) terpenes, (14E)- and (14Z)-dehydroheptaprenylcycline, were identified as minor metabolites in nonpathogenic Mycobacterium cells. C(35) terpenes could be biosynthesized by two routes, in which E and Z geometric isomers of heptaprenyl diphosphate are produced from E,E-FPP and E,E,E-GGPP, and the prenylreductase responsible for the biosynthesis of C(35) terpenes could reduce both E and Z prenyl residues.

Unique Biosynthesis of Sesquarterpenes (C35Terpenes)

“…4). 34) In addition, minor compounds 16 and 17, with a Z-and an E-double bond at C-14, respectively, were found to be present at a ratio of approximately 1:1 (Fig. 4).…”

“…4). 34) These results suggest not only that two distinct pathways (Fig. 4, pathways A and B), which use E,E-FPP and E,E,E-GGPP respectively as substrates of Mvan 3822, are utilized to biosynthesize sesquarterpenes (13)(14)(15)(16)(17)(18) in the cells, and also that polyprenyl reductase (PR) can reduce both the Z and the E double bonds at C-14 of compounds 20 and 21.…”

“…4, 13-18) that differ from sesquarterpenes 2-8 in B. subtilis have been found in nonpathogenic Mycobacterium species (Table 1). [32][33][34][35] Our biosynthesis study using cell-free extracts of M. chlorophenolicum indicated that a cyclic sesquarter- pene (heptaprenylcycline, 13) is biosynthesized via cyclization of a linear C 35 isoprenoid (19) (Fig. 4).…”

“…4, pathways A and B), which use E,E-FPP and E,E,E-GGPP respectively as substrates of Mvan 3822, are utilized to biosynthesize sesquarterpenes (13)(14)(15)(16)(17)(18) in the cells, and also that polyprenyl reductase (PR) can reduce both the Z and the E double bonds at C-14 of compounds 20 and 21. 34) In 2012, a new sesquarterpene, 18, was isolated from M. chlorophenolicum cells grown to stationary phase. 35) The absence of compound 22 suggests that the main sesquarterpenes (13)(14)(15) are biosynthesized only via pathway B in the stationary phase, in contrast to the logarithmic growth phase, in which both pathway A and pathway B are involved.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] In contrast, little is known about C 35 terpenes. To the best of my knowledge, only 19 cyclic and eight linear C 35 terpenes have been identified to date, [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and no family name was assigned to this terpene class until 2011. In 2011, it was proposed that these C 35 terpenes should be called sesquarterpenes as described below.…”