Conformational Differences Are Observed for the Active and Inactive Forms of Pinholin S Using DEER Spectroscopy.

Bacteriophages have evolved with an efficient host cell lysis mechanism to terminate the infection cycle and release the new progeny virions at the optimum time, allowing adaptation with the changing host and environment. Among the lytic proteins, holin controls the first and rate-limiting step of host cell lysis by permeabilizing the inner membrane at an allele-specific time known as "holin triggering". Pinholin S is a prototype holin of phage Φ21 which makes many nanoscale holes and destroys the proton motive force, which in turn activates the signal anchor release (SAR) endolysin system to degrade the peptidoglycan layer of the host cell and destruction of the outer membrane by the spanin complex.

Solid phase synthesis and spectroscopic characterization of the active and inactive forms of bacteriophage S pinholin protein.

The mechanism for the lysis pathway of double-stranded DNA bacteriophages involves a small hole-forming class of membrane proteins, the holins. This study focuses on a poorly characterized class of holins, the pinholin, of which the S protein of phage ϕ21 is the prototype. Here we report the first in vitro synthesis of the wildtype form of the S pinholin, S68, and negative-dominant mutant form, SIRS, both prepared using solid phase peptide synthesis and studied using biophysical techniques.