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Int J Med Microbiol. 2016 Nov;306(7):486-494. doi: 10.1016/j.ijmm.2016.07.002. Epub 2016 Aug 2.

Colicins U and Y inhibit growth of Escherichia coli strains via recognition of conserved OmpA extracellular loop 1.

Author information

1
Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic.
2
Department of Environment Protection Engineering, Faculty of Technology, Tomas Bata University in Zlín, T. G. Masaryk square 275, Zlín, Czech Republic.
3
Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic. Electronic address: dsmajs@med.muni.cz.

Abstract

Interactions of colicins U and Y with the OmpA (Outer membrane protein A) receptor molecule were studied using site-directed mutagenesis and colicin binding assay. A systematic mutagenesis of the colicin-susceptible OmpA sequence from Escherichia coli (OmpAEC) to the colicin-resistant OmpA sequence from Serratia marcescens (OmpASM) was performed in regions corresponding to extracellular OmpA loops 1-4. Susceptibility to colicins U and Y was significantly affected by the OmpA mutation in loop 1. As with functional analysis, a decrease in binding capacity of His-tagged colicin U was found for recombinant OmpA with a mutated segment in loop 1 compared to control OmpAEC. To verify the importance of the identified amino acid residues in OmpA loop 1, we introduced loop 1 from OmpAEC into OmpASM, which resulted in the substantial increase of susceptibility to colicins U and Y. In addition, colicins U and Y were tested against a panel of 118 bacteriocin non-producing strains of four Escherichia species, including E. coli (39 strains), E. fergusonii (10 strains), E. hermannii (42 strains), and E. vulneris (27 strains). A majority (82%) of E. coli strains was susceptible to colicins U and Y. Interestingly, colicins U and Y also inhibited all of the 30 tested multidrug-resistant E. coli O25b-ST131 isolates. These findings, together with the fact that OmpA loop 1 is important for bacterial virulence and is evolutionary conserved, offer the potential of using colicins U and Y as specific anti-OmpA loop 1 directed antibacterial proteins.

KEYWORDS:

Colicin U; Colicin Y; Colicin-receptor interaction; Escherichia coli; OmpA

PMID:
27510856
DOI:
10.1016/j.ijmm.2016.07.002
[Indexed for MEDLINE]

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