Molecular Characterization of a New Abortive Infection System (AbiU) from Lactococcus lactis LL51-1

September 2002

Published in: Applied and Environmental Microbiology, Nov. 2001, p. 5225-5232 Vol. 67, No. 11

By Gang Dai, Ping Su, Gwen E. Allison, Bruce L. Geller, Ping Zhu, Woojin S. Kim and Noel W. Dunn
DSM Food Specialties, P.O.Box 83, Moorebank, NSW 2170, Australia, Department of Microbiology, Oregon State University, Corvallis, Oregon 97331-3804, USA and Department of Biotechnology, University of New South Wales, Sydney, NSW 2052, Australia

This study reports on the identification and characterization of a novel abortive infection system, AbiU, from Lactococcus lactis. AbiU confers resistance to phages from the three main industrially relevant lactococcal phage species: c2, 936, and P335. The presence of AbiU reduced the efficiency of plaquing against specific phage from each species as follows: 3.7 x 10-1 , 1.0 x 10-2 , and 1.0 x 10-1 , respectively. abiU involves two open reading frames, abiU1 (1,772 bp) and abiU2 (1,019 bp). Evidence indicates that AbiU1 is responsible for phage resistance and that AbiU2 may downregulate phage resistance against 936 and P335 type phages but not c2 type phage. AbiU appeared to delay transcription of both phage 712 and c2, with the effect being more marked on phage c2.

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