Cyclization of fungal nonribosomal peptides by a terminal condensation-like domain

Abstract

Cyclization of linear peptidyl precursors produced by nonribosomal peptide synthetases (NRPSs) is an important step in the biosynthesis of bioactive cyclic peptides. Whereas bacterial NRPSs use thioesterase (TE) domains to perform the cyclization, fungal NRPSs have apparently evolved to use a different enzymatic route. In verified fungal NRPSs that produce macrocyclic peptides, each megasynthetase terminates with a condensation-like (CT) domain that may perform the macrocyclization reaction. To probe the role of such a CT domain, we reconstituted the activities of the Penicillium aethiopicum trimodular NPRS TqaA in Saccharomyces cerevisiae and in vitro. Together with a reconstituted bimodular NRPS AnaPS, we dissected the cyclization steps of TqaA in transforming the linear anthranilate-D-tryptophan-L-alanyl tripeptide into fumiquinazoline F. Extensive biochemical and mutational studies confirmed the essential role of the CT domain in catalyzing cyclization in a thiolation domain-dependent fashion. Our work provided evidence of a likely universal macrocyclization strategy employed by fungal NRPSs.

Decatransin, a novel natural product inhibiting protein translocation at the Sec61/SecY translocon

“…In addition, N-methyltransferases were present at positions 4, 5, 7 and 10, consistent with the observed N-methylation patterns. Finally, the synthetase had a terminal condensation domain (C T ) catalyzing the cyclization of NRPS products in fungi (Gao et al, 2012). The presence of a 2-hydroxy-acid dehydrogenase gene in the neighborhood of the NRPS (Fig.…”

Biosynthesis and Molecular Genetics of Peptaibiotics—Fungal Peptides Containing Alpha, Alpha-Dialkyl Amino Acids

“…Recently, Gao et al proposed a universal macrocyclization strategy for fungal NRPSs [64]. The megaenzyme terminates with a condensation-like domain that may perform the macrocyclization reaction [64].…”

Biosynthesis of fungal indole alkaloids

“…The trimodular NRPS from the tqa biosynthetic pathway, TqaA, has been expressed from Saccharomyces cerevisiae and functionally reconstituted in vitro. 58 Synthesis of 28 can be observed upon incubation of the amino acid substrates and cofactors in the presence of TqaA Removal of C T led to the hydrolysis of the linear tripeptide, which does not spontaneously cyclize under aqueous conditions. When the tripeptide is tethered to the last T domain of TqaA, the standalone C T domain catalysed the formation of 28 .…”