Genetic Dissection of T4 Lysis |
| |
| Authors: | Samir H Moussa Jessica L Lawler Ry Young |
| |
| Institution: | aDepartment of Biology, Texas A&M University, College Station, Texas, USA;bCenter for Phage Technology, Texas A&M University, College Station, Texas, USA;cDepartment of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA |
| |
| Abstract: | t is the holin gene for coliphage T4, encoding a 218-amino-acid (aa) protein essential for the inner membrane hole formation that initiates lysis and terminates the phage infection cycle. T is predicted to be an integral membrane protein that adopts an Nin-Cout topology with a single transmembrane domain (TMD). This holin topology is different from those of the well-studied holins S105 (3 TMDs; Nout-Cin) of the coliphage lambda and S68 (2 TMDs; Nin-Cin) of the lambdoid phage 21. Here, we used random mutagenesis to construct a library of lysis-defective alleles of t to discern residues and domains important for holin function and for the inhibition of lysis by the T4 antiholin, RI. The results show that mutations in all 3 topological domains (N-terminal cytoplasmic, TMD, and C-terminal periplasmic) can abrogate holin function. Additionally, several lysis-defective alleles in the C-terminal domain are no longer competent in binding RI. Taken together, these results shed light on the roles of the previously uncharacterized N-terminal and C-terminal domains in lysis and its real-time regulation. |
| |
| Keywords: | |
|
|
