TY  - JOUR
A1  - Stephan, Mareike Sophia
A1  - Bröker, Nina K.
A1  - Saragliadis, Athanasios
A1  - Roos, Norbert
A1  - Linke, Dirk
A1  - Barbirz, Stefanie
T1  - In vitro analysis of O-antigen-specific bacteriophage P22 inactivation by Salmonella outer membrane vesicles
JF  - Frontiers in microbiology
N2  - Bacteriophages use a large number of different bacterial cell envelope structures as receptors for surface attachment. As a consequence, bacterial surfaces represent a major control point for the defense against phage attack. One strategy for phage population control is the production of outer membrane vesicles (OMVs). In Gram-negative host bacteria, O-antigen-specific bacteriophages address lipopolysaccharide (LPS) to initiate infection, thus relying on an essential outer membrane glycan building block as receptor that is constantly present also in OMVs. In this work, we have analyzed interactions ofSalmonella(S.) bacteriophage P22 with OMVs. For this, we isolated OMVs that were formed in large amounts during mechanical cell lysis of the P22 S. Typhimurium host.In vitro, these OMVs could efficiently reduce the number of infective phage particles. Fluorescence spectroscopy showed that upon interaction with OMVs, bacteriophage P22 released its DNA into the vesicle lumen. However, only about one third of the phage P22 particles actively ejected their genome. For the larger part, no genome release was observed, albeit the majority of phages in the system had lost infectivity towards their host. With OMVs, P22 ejected its DNA more rapidly and could release more DNA against elevated osmotic pressures compared to DNA release triggered with protein-free LPS aggregates. This emphasizes that OMV composition is a key feature for the regulation of infective bacteriophage particles in the system.
KW  - bacteriophage
KW  - bacterial outer membrane vesicles
KW  - O-antigen
KW  - bacterial
KW  - membrane fractionation
KW  - Salmonella
KW  - lipopolysaccharide
Y1  - 2020
U6  - https://doi.org/10.3389/fmicb.2020.510638
SN  - 1664-302X
VL  - 11
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Broeker, Nina K.
A1  - Kiele, Franziska
A1  - Casjens, Sherwood R.
A1  - Gilcrease, Eddie B.
A1  - Thalhammer, Anja
A1  - Koetz, Joachim
T1  - In Vitro Studies of Lipopolysaccharide-Mediated DNA Release of Podovirus HK620
JF  - Viruses
N2  - Gram-negative bacteria protect themselves with an outermost layer containing lipopolysaccharide (LPS). O-antigen-specific bacteriophages use tailspike proteins (TSP) to recognize and cleave the O-polysaccharide part of LPS. However, O-antigen composition and structure can be highly variable depending on the environmental conditions. It is important to understand how these changes may influence the early steps of the bacteriophage infection cycle because they can be linked to changes in host range or the occurrence of phage resistance. In this work, we have analyzed how LPS preparations in vitro trigger particle opening and DNA ejection from the E. coli podovirus HK620. Fluorescence-based monitoring of DNA release showed that HK620 phage particles in vitro ejected their genome at velocities comparable to those found for other podoviruses. Moreover, we found that HK620 irreversibly adsorbed to the LPS receptor via its TSP at restrictive low temperatures, without opening the particle but could eject its DNA at permissive temperatures. DNA ejection was solely stimulated by LPS, however, the composition of the O-antigen dictated whether the LPS receptor could start the DNA release from E. coli phage HK620 in vitro. This finding can be significant when optimizing bacteriophage mixtures for therapy, where in natural environments O-antigen structures may rapidly change.
KW  - O-antigen specific phage
KW  - podovirus
KW  - HK620
KW  - lipopolysaccharide
KW  - in vitro particle opening
KW  - tailspike protein
Y1  - 2018
U6  - https://doi.org/10.3390/v10060289
SN  - 1999-4915
VL  - 10
IS  - 6
SP  - 1
EP  - 15
PB  - Molecular Diversity Preservation International (MDPI)
CY  - Basel
ER  -