Characterization of a receptor for small isometric headed phages of Lactococcus lactis

September 2002

Poster abstract for the Seventh Symposium on lactic Acid Bacteria Genetics, Metabolism and Applications, Egmond aan Zee, the Netherlands, 1-5 September 2002

By Hang Thu Ngo, Ping Su, Noel Dunn, and Bruce L. Geller
DSM Food Specialties, P.O.Box 83, Moorebank, NSW 2170, Australia, Department of Microbiology, Oregon State University, Corvallis, Oregon, USA and Department of Biotechnology, University of New South Wales, Sydney, NSW 2052, Australia

Purified plasma membrane from L. lactis sub. lactis LM2301 bound and inactivated phage sk1 in vitro. The rate of inactivation was proportional to the concentration of membranes. However, the membrane was saturated at about 6 to 12 PFU/ fmole membrane phosphate. Plasma membrane from E. coli did not bind or inactivate phage sk1. Boiling, washing in 2 M KCl, 8M urea or 0.1 M Na2CO3/pH 11, or treating the membranes with proteases did not reduce binding or inactivation of phage. Binding and inactivation were significantly reduced by including a-glycerol phosphate, EGTA, or high concentrations of NaCl in the mixture of phage and membrane. NaHPO4, Glycerol, or other components of the plasma membrane did not inhibit binding or inactivation. The phage-inactivating substance was solubilized by a non-ionic detergent and remained in the supernatant after centrifugation. The phage-inactivating and binding activity was completely destroyed by treating the membrane with a muramidase. Cell wall was purified, and shown to inactivate phage sk1. However, binding and inactivation of phage sk1 by purified cell wall was not inhibited by a-glycerol phosphate, EGTA, or high concentrations of NaCl. One of 5 other small isometric-headed phages tested competed with phage sk1 for the binding site to membrane. Phages that did not bind to the membrane did not reduce the inactivation of phage sk1. The results suggest that a receptor for phage sk1 and other, but not all similar phages, includes both membrane lipoteichoic acid and intact cell wall, but not protein.

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