HetI-Like Phosphopantetheinyl Transferase Posttranslationally Modifies Acyl Carrier Proteins in spp.

In spp., the biosynthesis of the yellow pigment xanthomonadin and fatty acids originates in the type II polyketide synthase (PKS II) and fatty acid synthase (FAS) pathways, respectively. The acyl carrier protein (ACP) is the central component of PKS II and FAS and requires posttranslational phosphopantetheinylation to initiate these pathways. In this study, for the first time, we demonstrate that the posttranslational modification of ACPs in pv. is performed by an essential 4'-phosphopantetheinyl transferase (PPTase), XcHetI (encoded by Xc_4132). pv. strain could not be deleted from the pv. genome unless another PPTase-encoding gene such as or was present. Compared with wild-type strain pv. 8004 and mutant ::, strain :: failed to generate xanthomonadin pigments and displayed reduced pathogenicity for the host plant, . Further experiments showed that the expression of restored the growth of mutant HT253 and, when a plasmid bearing was introduced into , , which encodes the sole PPTase in , could be deleted. In in vitro enzymatic assays, XcHetI catalyzed the transformation of 4'-phosphopantetheine from coenzyme A to two pv. -acyl carrier proteins, XcAcpP and XcAcpC. All of these findings indicate that XcHetI is a surfactin PPTase-like PPTase with a broad substrate preference. Moreover, the HetI-like PPTase is ubiquitously conserved in spp., making it a potential new drug target for the prevention of plant diseases caused by .[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.