Structural and Biochemical Investigations of PlyC: a phage Lysin

J. Todd Hoopes (U of Maryland)

Bacteriophage lysins are a group of cell wall hydrolases involved in bacterial lysis during phage release at the end of the infectious cycle. All known lysins are produced as a single polypeptide containing a catalytically activity domain, often referred to as a CHAP domain (cysteine, histidine-dependent amidopeptidase), and a cell wall binding domain. PlyC, however, is an exception. This enzyme is a nonameric complex composed of a homo-octamer (PlyCB) and an active subunit (PlyCA) containing the CHAP site. While PlyC loses all activity at 42°C, CD and ITC studies show that the homo-octamer is stable to 75 °C and the PlyCB monomer does not denature until 90°C. Furthermore, crosslinking and FRET studies indicate that the octamer breaks apart at the 75°C transition and reforms when cooled. The crystal structure of PlyCB shows that the homo-octamer is a ring structure with a diameter of 80 Å and contains a 20 Å pore. Significantly, PlyC is several orders of magnitude more active than any other described lysin, a property that may be related to its unique structure. These and other properties raise intriguing possibilities for biotechnological applications.

Back to Seminar Home Page

Last modified 21-May-2010 by website owner: NCNR (attn: )