Phage Lysis: Do We Have the Hole Story Yet?
Dr. Ry Young; Professor, Texas A&M University
November 8 in the Fralin Auditorium, Fralin Hall 102
Hosted by Dr. Birgit Scharf
The infection cycle of Caudovirales, the “tailed” dsDNA phages that dominate the biosphere, ends with host lysis. From the time of the founding of Delbrueck’s “phage school” in the 1940s, it was clear that in Caudovirales infections, a muralytic enzyme, eventually designated as the “endolysin” that was required to degrade the bacterial murein (cell wall; peptidoglycan; PG, was produced. There was a lively debate as to whether these muralytic enzymes were host-encoded and simply activated by phage infection, but we now know that every such phage encodes at least one endolysin. Considering how important the last step in the infection cycle is, in that its timing and efficiency ultimately determines the yield of progeny virions and thus the evolutionary fecundity of the phage, it is perhaps not surprising that more viral genomic space is devoted to the lysis event other than the gene(s) for the endolysin. The seminar will summarize the current state of our understanding of phage lysis, focusing on the last step of the pathway, the destruction of the outer membrane. It will also define an ever-increasing roster of lysis proteins, including holins, antiholins, pinholins, antipinholins, SAR endolysins, i-spanins, o-spanins, u-spanins, disruptins and releasins, all involved in the implementation and regulation of the lysis pathway.