Interchangeability of the adsorption proteins of bacteriophages Ff and IKe

Abstract

The wild-type adsorption protein (g3p) of filamentous phage IKe cannot be exchanged with its analogous protein in the related Ff (M13, fd, and fl) phage particles. Deletion mutants of the protein, however, are assembled into Ff phage particles. These hybrid Ff phage particles bearing deleted IKe g3p attach to N pili, thus conserving the host attachment property of the protein but not its infection-initiating function. This means that the attachment specificity is determined by IKe g3p independently of other phage components in contact with it. Infection initiation function, the process in which phage DNA is released into the host, in contrast seems to require either more complex structural features of the protein (for example, a certain oligomeric structure) provided only in the original particle, or a concerted action of g3p with another particle component, not replaceable by its homologous counterpart in the related phage.

Structural and energetic basis of infection by the filamentous bacteriophage IKe

“…Here we examined the domain organization in the G3P of the filamentous phage IKe (Khatoon et al ., 1972; Peeters et al ., 1985; 1987), which infects E. coli cells carrying N pili (Bradley, 1979; Bradley et al ., 1983). As the other Ff phage, IKe possesses a G3P, which is believed to mediate infection in a similar fashion as in the case of phage fd by sequential interactions first with a pilus (the N pilus) and then with TolA (Endemann et al ., 1992; 1993). The IKe‐N2 domain (residues 112–180) shows a strong homology to the N1 domains of phage fd and phage IF1.…”