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Temperature sensitive mutation in the 38 kDa minor structural protein gene of phage MB78 interferes with phage

Pinaki Datta1, Prabhat Mallik, Amar N Ghosh

  • 1Molecular Biology Unit, Institute of Medical Sciences, Banaras Hindu University, Varanasi, U.P., India.

Virus Genes
|March 4, 2005
PubMed

Insights

A temperature-sensitive mutation in a Salmonella phage MB78 protein prevents tail fiber attachment, halting phage development. This structural protein is crucial for proper phage morphogenesis and assembly.

Area of Science:

  • Bacteriophage biology
  • Molecular genetics
  • Structural biology

Background:

  • Phage MB78 is a virulent phage that infects Salmonella enterica serovar typhimurium.
  • Bacteriophages are viruses that infect bacteria and play crucial roles in microbial ecosystems and biotechnology.
  • Understanding phage structure and assembly is essential for phage therapy and genetic engineering.

Purpose of the Study:

  • To investigate the function of the 38 kDa minor structural protein of phage MB78.
  • To elucidate the role of this protein in phage morphogenesis and assembly.
  • To identify the specific mutation responsible for temperature sensitivity.

Main Methods:

  • Generating and characterizing temperature-sensitive mutants of phage MB78.
  • Electron microscopy to analyze phage particle morphology.
  • DNA sequencing of the phage genome and mutant analysis.
  • Bioinformatic analysis of gene sequences and protein structure.

Main Results:

  • A temperature-sensitive mutation in the 38 kDa protein gene (A75V) disrupts phage development at restrictive temperatures.
  • Electron microscopy revealed tailless phage particles, including empty capsids and DNA-filled icosahedral particles.
  • The mutation affects the thermolability of the 38 kDa protein.
  • The 38 kDa protein is essential for the attachment of tail fibers to the phage capsid.

Conclusions:

  • The 38 kDa protein is indispensable for correct phage morphogenesis in MB78.
  • This protein plays a critical role in the assembly of functional phage particles by mediating tail fiber attachment.
  • The identified mutation provides a molecular basis for understanding temperature sensitivity in phage assembly.

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