Structural analysis and proteomics studies on the Myoviridae vibriophage M4
Bacteriophages play a crucial role in tracking the spread of bacterial epidemics. The frequent emergence of antibiotic-resistant bacterial strains throughout the world has motivated studies on bacteriophages that can potentially be used in phage therapy as an alternative to conventional antibiotic treatment. A recent outbreak of cholera in Haiti took many lives due to a rapid development of resistance to the available antibiotics. The properties of vibriophages, bacteriophages that infect Vibrio cholerae, are therefore of practical interest. A detailed understanding of the structure and assembly of a vibriophage is potentially useful in developing phage therapy against cholera as well as for fabricating artificial nanocontainers. Therefore, the aim of the present study was to determine the three-dimensional organization of vibriophage M4 at sub-nanometer resolution by electron microscopy and single-particle analysis techniques to facilitate its use as a therapeutic agent. We found that M4 has a large capsid with T = 13 icosahedral symmetry and a long contractile tail. This double-stranded DNA phage also contains a head-to-tail connector protein complex that joins the capsid to the tail and a prominent baseplate at the end of the tail. This study also provides information regarding the proteome of this phage, which is proteins similar to that of other Myoviridae phages, and most of the encoded proteins are structural proteins that form the exquisite architecture of this bacteriophage.
We are thankful to Dr. Shanta Dutta, the director of this institute, for her interest and encouragement in this study. This study was supported in part by financial assistance from CSIR, Government of India [Grant no. 21(0948)/13/EMR-II]. We are also thankful to Prof. Peter Rosenthal, Francis Crick Institute, London, UK, for allowing us to collect negative stain data. We also express our sincere thanks to Professor Steven J. Ludtke, Baylor College of Medicine, Houston, USA, and to Dr. Bernard Heymann, NIH, USA, for their expert comments regarding reconstructions. We are also thankful to UCSF for allowing us to use Chimera software. Access of NCBI-Blast search tool is also thankfully acknowledged. We are also very much thankful to Dr. Kalyan Mitra, CSIR-CDRI, Lucknow, for his immense support for this study. We are thankful to Dr. Ranjan Kumar Nandy, Dr. Sambit Roy, and Dr. Anuradha Sinha of this institute for helping us in performing the gel studies of proteins. We are also thankful to Mr. Sandip Chakraborty, technical officer, CSIR-IICB, Kolkata, for helping us with the MALDI-TOF study of proteins. S.D. performed research, analyzed data, processed data, and wrote the paper. M.D. performed research and analyzed data. A.S. analyzed and processed data. A.N.G. designed and performed research, analyzed and interpreted data, and corrected the paper. All authors have read and approved the paper.
Compliance with ethical standards
Conflict of interest
There are no conflicts of interest to declare.
No human subjects or animals were used in this study.
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