The effects on Escherichia coli of expression of the cloned bacteriophage T4 nucleoid disruption (ndd) gene.

Immediately after T4 bacteriophage infection, the Escherichia coli nucleoid undergoes rapid delocalization. The ndd gene of T4 is responsible for this nuclear disruption phenomenon. We have cloned two alleles of this gene and studied the effects of their expression on E. coli cells. We have shown that the Ndd protein (i) is able to reproduce the disruption of the nucleoid characteristic of T4 infection, (ii) is highly toxic and results in a logarithmic decrease in cell viability, and (iii) inhibits genomic DNA replication by blocking progression of replication forks. Induction of Ndd does not result in degradation of genomic DNA and does not significantly alter the general processes of transcription and translation during the entire period of exponential cell death. These results support the notion that the target of Ndd is some aspect of the nucleoid architecture.