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

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.

Antibacterial Activity of Bacteriocinogenic Commensal Escherichia coli against Zoonotic Strains Resistant and Sensitive to Antibiotics

“…Studies on the activity of bacteriocins, as an alternative to adjunctive therapy with antibiotics, and trials focused on probiotic bacteria are intensively conducted [31][32][33][34]. They concern mostly the bacteriocins of Gram-positive bacteria [35][36][37][38][39], but colicins and microcins are also tested as proteins with activity against pathogenic Gram-negative bacteria [40][41][42][43][44][45][46][47][48][49][50], including a few studies related to antibiotic-resistant strains [51,52]. However, nonclinical strains of animal origin, derived from farm animals that are particularly resistant to antibiotics, may reveal a distinct profile of sensitivity to bacteriocins.…”

The Effects of Colicin Production Rates on Allelopathic Interactions in Escherichia coli Populations

“…These changes could reduce toxin production, lowering metabolic costs and elevating the fitness of the sessile population, thus maintaining diversity in sessile communities, and it allows for the dispersal of beneficial traits. As colicins are effective inhibitors to enteric pathogens [37,38], our findings could also be used to develop means for the successful and sustainable inhibition of pathogens.…”

Bacteriocins: Potential for Human Health

“…They cross the intestinal barrier into the blood and reach other extraintestinal organs and cause the aggravation of the symptoms of the infection. Some studies have shown that bacteriocins (e.g., microcin and colicin) have an inhibitory effect on E. coli and Salmonella in vitro and can effectively reduce the numbers of E. coli (e.g., O157: H7) and Salmonella in the infected mice, improving the adverse effects caused by these pathogens [26][27][28]. In addition, some bacteriocins (e.g., subtilosin and gassericin E) have a significant inhibitory effect on the pathogens (e.g., Gardnerella vaginalis) which can cause the bacterial vaginal diseases [29,30].…”