Fluorescence changes of a membrane-bound dye during bacteriophage T5 infection of Escherichia coli

Area of Science:

• Molecular Biology
• Virology
• Microbiology

Background:

• Colicin Ib plasmids confer specific resistance mechanisms in bacterial hosts.
• Bacteriophage T5 employs a unique two-step DNA injection process.
• Membrane-bound fluorescent probes can report on cellular events.

Purpose of the Study:

• To investigate the host-phage interactions during T5 bacteriophage infection of bacteria harboring the colicin Ib plasmid.
• To determine if T5 bacteriophage DNA injection affects membrane-bound fluorescence.

Main Methods:

• Utilized N-phenyl-1-naphthylamine as a membrane-bound fluorescent probe.
• Performed T5 bacteriophage infections on bacterial hosts with and without the colicin Ib plasmid.
• Introduced mutations in both the phage and plasmid to assess infection outcomes.
• Monitored fluorescence intensity changes in response to infection.

Main Results:

• A dramatic increase in N-phenyl-1-naphthylamine fluorescence was observed specifically when T5 bacteriophage infected hosts containing the colicin Ib plasmid.
• This pronounced fluorescence increase was absent in normal infections or infections with mutated phage/plasmid that still allowed productive infection.
• Two smaller, distinct increases in fluorescence were detected in all T5 infections permitting the two-step DNA injection process.

Conclusions:

• The colicin Ib plasmid plays a critical role in the T5 bacteriophage infection process, influencing membrane dynamics.
• The observed fluorescence changes are linked to the specific mechanism of T5 bacteriophage DNA injection.
• N-phenyl-1-naphthylamine fluorescence can serve as a sensitive indicator of specific bacteriophage-host interactions during DNA translocation.