Colicin Z, a structurally and functionally novel colicin type that selectively kills enteroinvasive Escherichia coli and Shigella strains

Lenka Micenková,David Šmajs,Matěj Hrala,Tereza Dolejšová,Ondrej Šedo,Jiri Kucera,Dirk Linke,Radovan Fišer,Juraj Bosák

doi:10.1038/s41598-019-47488-8

Lenka Micenková, David Šmajs + Show 7 more

Open Access

https://doi.org/10.1038/s41598-019-47488-8

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Abstract

Colicin production in Escherichia coli (E. coli) strains represents an important trait with regard to microbial survival and competition in the complex intestinal environment. A novel colicin type, colicin Z (26.3 kDa), was described as a product of an original producer, extraintestinal E. coli B1356 strain, isolated from the anorectal abscess of a 17 years-old man. The 4,007 bp plasmid (pColZ) was completely sequenced and colicin Z activity (cza) and colicin Z immunity (czi) genes were identified. The cza and czi genes are transcribed in opposite directions and encode for 237 and 151 amino acid-long proteins, respectively. Colicin Z shows a narrow inhibitory spectrum, being active only against enteroinvasive E. coli (EIEC) and Shigella strains via CjrC receptor recognition and CjrB- and ExbB-, ExbD-mediated colicin translocation. All tested EIEC and Shigella strains isolated between the years 1958–2010 were sensitive to colicin Z. The lethal effect of colicin Z was found to be directed against cell wall peptidoglycan (PG) resulting in PG degradation, as revealed by experiments with Remazol Brilliant Blue-stained purified peptidoglycans and with MALDI-TOF MS analyses of treated PG. Colicin Z represents a new class of colicins that is structurally and functionally distinct from previously studied colicin types.

Highlights

Both commensal and pathogenic Escherichia coli strains encode systems for competition among bacterial strains/ species allowing survival in the complex intestinal environment
The original colicin Z producer E. coli B1356 (Table 1) was identified as extraintestinal pathogenic E. coli belonging to phylogenetic group D, which contained 4 out of the 20 tested virulence determinants
From the set of standard indicator strains, the E. coli B1356 strain inhibited only the growth of S. sonnei 17. Based on these results we suggested that this was a novel colicin type, encoded by E. coli B1356 strain, which we named colicin Z

Summary

Introduction

Both commensal and pathogenic Escherichia coli strains encode systems for competition among bacterial strains/ species allowing survival in the complex intestinal environment. E. coli strains have been shown to produce two different bacteriocin types including colicins and microcins[2,3,4,5]. Bacteriocin production appears to facilitate the invasion of a particular bacterial strain into an established microbial community. It may mediate defense against invasion of other strains into the occupied niche[8,9,10]. Known colicin types differ in a number of characteristics including mechanism of their release from the producer cell, types of translocation systems used to traverse the cell envelope, mechanism of killing action, receptor specificity, as well as several others[3,4]. The colicin Z receptor, translocation system, and mode of action were determined

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