Dramatic decay of phage transcripts in lactococcal cells carrying the abortive infection determinant AbiB.

The abortive infection determinant AbiB prevents growth of the sensitive phage bIL170, but not of the resistant phage bIL41, on Lactococcus lactis strain IL1403. Here we show that AbiB promotes a dramatic degradation of sensitive phage transcripts, starting 10-15 min after infection. The decay of the transcripts is the probable cause of the arrest of the sensitive phage development. Mapping of the 5' end of degradation products established that they result from endonucleolytic cleavage preferentially at U/U, A/U and U/A sites. We propose that an early product of the sensitive phage either induces the synthesis or stimulates the activity of an RNase in an AbiB+ cell.