DETECTING THE ABILITY OF VIRAL, BACTERIAL AND EUKARYOTIC REPLICATION PROTEINS TO TRACK ALONG DNA

The phage T4 gene 45 protein (gp45), Escherichia coli beta and the euk aryotic proliferating cell nuclear antigen (PCNA) function in replicat ion as processivity factors of their corresponding DNA polymerases. Th e T4 gp45 also functions as the transcriptional activator that connect s expression of viral late genes to DNA replication. DNA tracking is a n essential component of the replication and transcription regulatory functions of T4 gp45. The ability of gp45, beta and PCNA to track alon g DNA has been analyzed by photocrosslinking. Each of these proteins m ust be loaded onto DNA by a species-specific assembly factor. For gp45 and beta, the density of traffic along DNA is determined by a dynamic balance between continuous protein loading and unloading, and is also dependent on interaction with the conjugate single-stranded DNA bindi ng protein.