A phosphopantetheinylating polyketide synthase producing a linear polyene to initiate enediyne antitumor antibiotic biosynthesis

Abstract

The enediynes, unified by their unique molecular architecture and mode of action, represent some of the most potent anticancer drugs ever discovered. The biosynthesis of the enediyne core has been predicted to be initiated by a polyketide synthase (PKS) that is distinct from all known PKSs. Characterization of the enediyne PKS involved in C-1027 (SgcE) and neocarzinostatin (NcsE) biosynthesis has now revealed that (i) the PKSs contain a central acyl carrier protein domain and C-terminal phosphopantetheinyl transferase domain; (ii) the PKSs are functional in heterologous hosts, and coexpression with an enediyne thioesterase gene produces the first isolable compound, 1,3,5,7,9,11,13-pentadecaheptaene, in enediyne core biosynthesis; and (iii) the findings for SgcE and NcsE are likely shared among all nine-membered enediynes, thereby supporting a common mechanism to initiate enediyne biosynthesis.C-1027 ͉ neocarzinostatin ͉ phosphopantetheinyl transferase

Polyketide synthase chemistry does not direct biosynthetic divergence between 9- and 10-membered enediynes

“…Thus, the phylogenetic divergence between 9-and 10-membered PKSEs may reflect enediyne core-specific protein-protein interactions between the PKSE and corresponding accessory enzymes. This hypothesis is consistent with our earlier observation that only the 9-membered pksE genes, but not calE8, could restore C-1027 or NCS production in pksE null mutants (15). As an important first step toward elucidating pathway-directing interactions between PKSEs and accessory enzymes, we demonstrated the production of 1 by all possible PKSE-TE combinations.…”

“…S2) and expected mass of 198.1 and confirmed to be identical to the previously characterized authentic standard (15). Productions of 1 by either the 9-or 10-membered PKSE-TE systems under the conditions examined are very similar as exemplified by the estimated yields of 1 at 1.3 AE 0.5 mg∕L for CalE8-CalE7 and 2.8 AE 1.0 mg∕L for MdpE-MdpE10, respectively.…”

“…The difficulties with in vitro experimental systems for PKSE studies contrast sharply with our previously reported in vivo system, in which expression of pksE-TE from either the C-1027 or NCS biosynthetic machineries in either Escherichia coli or Streptomyces consistently provided 1 as the only major product (15). The apparent advantage of in vivo methods may reflect the difficulty of reconstituting the large multifunctional PKSE megaenzyme in vitro in the absence of the mild and regenerative conditions of the cell in vivo.…”

“…2B). For instance, we previously reported that NcsE and SgcE-the PKSEs involved in the biosynthesis of the 9-membered enediynes NCS and C-1027, respectively-produced heptaene (1) when coexpressed with their associated TEs, NcsE10 and SgcE10 (15,16). In contrast, Liang and coworkers observed methyl hexaenone (2) as the major product of the in vitro combination of CalE8 and CalE7, the PKSE-TE pair from the 10-membered enediyne CAL (17).…”

A Sfp-type phosphopantetheinyl transferase ZmsO is essential for zeamines production and the virulence of Dickeya zeae

“…Comparative analysis showed that ACPS-type PPTases usually contain about 120 amino acids carrying motif P2 [(V/I)G(V/I)D] and motif P3 [(F/W)(S/C/T/)xKE(A/S)xxK] (Lambalot et al 1996), whereas the Sfp-type PPTases contain about 220 amino acids with motifs P2 and P3 plus motif P1 [PxWPxGxxGS(M/L)THCxGY] (Sanchez et al 2001). The third type of PPTases is fused with fatty acid synthases or polyketide synthases as a functional domain (Murugan and Liang 2008;Zhang et al 2008).…”