A high-throughput genomic screen identifies a role for the plasmid-borne type II secretion system of Escherichia coli O157:H7 (Sakai) in plant-microbe interactions

Ashleigh Holmes, Leighton Pritchard, Peter E. Hedley, Jenny Morris, Sean P. McAteer, David L. Gally, Nicola J. Holden

Research output: Contribution to journalArticlepeer-review


Shiga-toxigenic Escherichia coli (STEC) is often transmitted into food via fresh produce plants, where it can cause disease. To identify early interaction factors for STEC on spinach, a high-throughput positive-selection system was used. A bacterial artificial chromosome (BAC) clone library for isolate Sakai was screened in four successive rounds of short-term (2 h) interaction with spinach roots, and enriched loci identified by microarray. A Bayesian hierarchical model produced 115 CDS credible candidates, comprising seven contiguous genomic regions. Of the two candidate regions selected for functional assessment, the pO157 plasmid-encoded type two secretion system (T2SS) promoted interactions, while a chaperone-usher fimbrial gene cluster (loc6) did not. The T2SS promoted bacterial binding to spinach and appeared to involve the EtpD secretin protein. Furthermore, the T2SS genes, etpD and etpC, were expressed at a plant-relevant temperature of 18 °C, and etpD was expressed in planta by E. coli Sakai on spinach plants.

Original languageEnglish
Pages (from-to)4242-4253
Number of pages12
Issue number6
Early online date12 Jul 2020
Publication statusPublished - 30 Nov 2020


  • escherichia coli
  • bacteria
  • Sakai
  • STEC
  • VTEC
  • general secretory pathway
  • pO157-cured
  • spinach
  • enrichment screen

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