Ustiloxins, fungal cyclic peptides, are ribosomally synthesized in <i>Ustilaginoidea virens</i>

<jats:title>Abstract</jats:title> <jats:p>Motivation: Ustiloxins A and B are toxic cyclic tetrapeptides, Tyr-Val/Ala-Ile-Gly (Y-V/A-I-G), that were originally identified from Ustilaginoidea virens, a pathogenic fungus affecting rice plants. Contrary to our report that ustiloxin B is ribosomally synthesized in Aspergillus flavus, a recent report suggested that ustiloxins are synthesized by a non-ribosomal peptide synthetase in U.virens. Thus, we analyzed the U.virens genome, to identify the responsible gene cluster.</jats:p> <jats:p>Results: The biosynthetic gene cluster was identified from the genome of U.virens based on homologies to the ribosomal peptide biosynthetic gene cluster for ustiloxin B identified from A.flavus. It contains a gene encoding precursor protein having five Tyr-Val-Ile-Gly and three Tyr-Ala-Ile-Gly motifs for ustiloxins A and B, respectively, strongly indicating that ustiloxins A and B from U.virens are ribosomally synthesized.</jats:p> <jats:p>Availability and implementation: Accession codes of the U.virens and A.flavus gene clusters in NCBI are BR001221 and BR001206, respectively.</jats:p> <jats:p>Contact:  umemura-m@aist.go.jp or asai@k.u-tokyo.ac.jp</jats:p> <jats:p>Supplementary information:  Supplementary data are available at Bioinformatics online.</jats:p>