Identification of the Wzx flippase, Wzy polymerase and sugar-modifying enzymes for spore coat polysaccharide biosynthesis in Myxococcus xanthus

María Pérez-Burgos, Inmaculada García-Romero, Miguel A. Valvano, Lotte Søgaard-Andersen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The rod‐shaped cells of Myxococcus xanthus, a Gram‐negative deltaproteobacterium, differentiate to environmentally resistant spores upon starvation or chemical stress. The environmental resistance depends on a spore coat polysaccharide that is synthesized by the ExoA‐I proteins, some of which are part of a Wzx/Wzy‐dependent pathway for polysaccharide synthesis and export; however, key components of this pathway have remained unidentified. Here, we identify and characterize two additional loci encoding proteins with homology to enzymes involved in polysaccharide synthesis and export, as well as sugar modification, and show that six of the proteins encoded by these loci are essential for the formation of environmentally resistant spores. Our data support that MXAN_3260, renamed ExoM, and MXAN_3026, renamed ExoJ, are the Wzx flippase and Wzy polymerase, respectively responsible for translocation and polymerization of the repeat unit of the spore coat polysaccharide. Moreover, we provide evidence that three glycosyltransferases (MXAN_3027/ExoK, MXAN_3262/ExoO and MXAN_3263/ExoP) and a polysaccharide deacetylase (MXAN_3259/ExoL) are important for formation of the intact spore coat, while ExoE is the polyisoprenyl‐phosphate hexose‐1‐phosphate transferase responsible for initiating repeat unit synthesis, likely by transferring N‐acetylgalactosamine‐1‐P to undecaprenyl‐phosphate. Together, our data generate a more complete model of the Exo pathway for spore coat polysaccharide biosynthesis and export.
Original languageEnglish
JournalMolecular Microbiology
Early online date16 Feb 2020
DOIs
Publication statusEarly online date - 16 Feb 2020

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