Bacteriophage T4: Molecular aspects of bacterial cell infection and the role of capsid proteins

Bacteriophage T4 of the Myoviridae family is ubiquitous in the environment and living organisms. In microbiology it has become a universal research model for the mechanisms of many biological processes, including bacteriophage infection. T4 phage is a tailed phage, the most frequent bacteriophage group. It is made up of a head, a contractile tail, and dsDNA. Its tail is a complex structure composed of a collar and its whiskers, a tail tube, a base plate, short fibers, and tail fibers. All these elements cooperate in effective infection. The main host of bacteriophage T4 is Escherichia coli. Adsorption on the bacterial surface is crucial for infection. It depends on specific receptors: lipopolysaccharides and OmpC protein. The high bacteriophage specificity requires specific structures (compositions) of both bacterial and bacteriophage (gp12, gp37) elements. The introduction of phage DNA into the bacterium engages a group of proteins, for example those essential for effective tail contraction and membrane fusion and those with enzymatic activity. In the infected bacterial cell, T4 starts to control cell metabolism with phage replication and expression factors. The final stage of infection is assemblage and lysis. Here the role of bacterial and bacteriophage elements in the above processes is presented and their cooperation with regard to currently identified molecular regions of activity.