Multimodular type I polyketide synthases in algae evolve by module duplications and displacement of AT domains in trans.

Ekaterina Shelest,Severin Sasso,Maximilian Fichtner,Natalie Heimerl

doi:10.1186/s12864-015-2222-9

Ekaterina Shelest, Severin Sasso + Show 2 more

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https://doi.org/10.1186/s12864-015-2222-9

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Abstract

BackgroundPolyketide synthase (PKS) catalyzes the biosynthesis of polyketides, which are structurally and functionally diverse natural products in microorganisms and plants. Here, we have analyzed available full genome sequences of microscopic and macroscopic algae for the presence of type I PKS genes.ResultsType I PKS genes are present in 15 of 32 analyzed algal species. In chlorophytes, large proteins in the MDa range are predicted in most sequenced species, and PKSs with free-standing acyltransferase domains (trans-AT PKSs) predominate. In a phylogenetic tree, PKS sequences from different algal phyla form clades that are distinct from PKSs from other organisms such as non-photosynthetic protists or cyanobacteria. However, intermixing is observed in some cases, for example polyunsaturated fatty acid (PUFA) and glycolipid synthases of various origins. Close relationships between type I PKS modules from different species or between modules within the same multimodular enzyme were identified, suggesting module duplications during evolution of algal PKSs. In contrast to type I PKSs, nonribosomal peptide synthetases (NRPSs) are relatively rare in algae (occurrence in 7 of 32 species).ConclusionsOur phylogenetic analysis of type I PKSs in algae supports an evolutionary scenario whereby integrated AT domains were displaced to yield trans-AT PKSs. Together with module duplications, the displacement of AT domains may constitute a major mechanism of PKS evolution in algae. This study advances our understanding of the diversity of eukaryotic PKSs and their evolutionary trajectories.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2222-9) contains supplementary material, which is available to authorized users.

Highlights

Polyketide synthase (PKS) catalyzes the biosynthesis of polyketides, which are structurally and functionally diverse natural products in microorganisms and plants
Distribution of type I polyketide synthases and nonribosomal peptide synthetases predicted in algae To refine our picture of the occurrence of type I PKSs and NRPSs in algae, we analyzed genome sequences available for 32 different algal species (Additional file 1: Table S1)
PKS and NRPS candidates were identified by scanning the genomes for characteristic KS and condensation (C) domains, by BLAST [21] and/or InterProScan [22]

Summary

Introduction

Polyketide synthase (PKS) catalyzes the biosynthesis of polyketides, which are structurally and functionally diverse natural products in microorganisms and plants. Polyketide synthases (PKSs) occur in many different microorganisms, where they are involved in the biosynthesis of compounds with a variety of structures and functions. Shelest et al BMC Genomics (2015) 16:1015 synthase are involved in the biosynthesis of long-chain polyhydroxy alcohols and contribute to the formation of the glycolipid envelope in cyanobacterial heterocysts [6, 7]. These findings illustrate that FAS, PUFA synthase and PKS are mechanistically closely related, and that FAS and PUFA synthase may be viewed as special cases of PKS [3]. PKS often occurs as a hybrid enzyme with nonribosomal peptide synthetase (NRPS), which resembles noniterative type I PKS, module domain AT ACP KS AT ACP type I PKS

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