The phage infection process: A functional role for the distal linker region of bacteriophage protein 3

The filamentous bacteriophage infects Escherichia coli by interaction with the F pilus and the TolQRA complex. The virus-encoded protein initiating th is process is the gene 3 protein (g3p). The g3p molecule can be divided int o three different domains separated by two glycine-rich linker regions. Tho ugh there has been extensive evaluation of the importance of the diverse do mains of g3p, no proper function has so far been assigned to these linker r egions, Through the design of mutated variants of g3p that were displayed o n the surface of bacteriophage, we were able to elucidate a possible role f or the distal glycine-rich linker region. A phage that displayed a g3p comp rised of only the N1 domain, the first linker region, and the C-terminal do main was able to infect cells at almost the same frequency as the wild-type phage. This infection was proven to be dependent on the motif between amin o acid residues 68 and 86 (i.e., the first glycine-rich linker region of g3 p) and on F-pilus expression.