Preparation of pyrrolo[2,3-b]indoles carrying a β-configured reverse C3-dimethylallyl moiety by using a recombinant prenyltransferase CdpC3PT

Abstract

Six beta-configured reversely C3-prenylated pyrrolo[2,3-b]indoles were successfully prepared by using a recombinant prenyltransferase from Neosartorya fischeri. For this purpose, the putative prenyltransferase gene NFIA_074280 (termed herewith cdpC3PT) was cloned into pQE60 and overexpressed in Escherichia coli. The overproduced His(6)-CdpC3PT was purified to near homogeneity and incubated with five cyclic tryptophan-containing dipeptides in the presence of dimethylallyl diphosphate (DMAPP). All of the substrates were accepted by CdpC3PT and converted to reversely C3-prenylated pyrrolo[2,3-b]indoles. Using cyclo-l-Trp-l-Trp as substrate, both mono- and diprenylated derivatives were obtained. The structures of the enzymatic products were confirmed by HR-ESI-MS, (1)H- and (13)C-NMR analyses as well as by long-range (1)H-(13)C connectivities in heteronuclear multiple-bond correlation (HMBC) spectra after preparative isolation. (1)H-(1)H spatial correlations in nuclear overhauser effect spectroscopy (NOESY) were used for determination of absolute configuration. The K(M) values were determined at about 1.5 mM for DMAPP and in the range from 0.22 to 5.5 mM for cyclic dipeptides. The turnover number k(cat) were found in the range of 0.023 to 0.098 s(-1) and specificity constants k(cat)/K(M) from 14.2 to 122.7 M(-1) s(-1). In contrast to the products of AnaPT bearing alpha-configured C3-dimethylallyl residues, the C3-prenyl moieties in the products of CdpC3PT have a beta-configuration. Discovery and characterisation of CdpC3PT expand the usage of the chemoenzymatic approach for stereospecific synthesis of C3-prenylated derivatives.