Welcome to the web supplement to the paper:
"Recruitment of terminal protein to the ends of Streptomyces linear plasmids and chromosomes by a novel telomere binding protein essential for linear DNA replication". Kai Bao and Stanley N. Cohen.
Genes & Development, Vol. 17, Issue 6, pp. 774-785, March 15, 2003
Bidirectional replication of Streptomyces linear plasmids and chromosomes from a central origin produces unpaired 3' leading strand overhangs at the telomeres of replication intermediates. Filling in of these overhangs leaves a terminal protein attached covalently to the 5' DNA ends of mature replicons. We report here the essential role of a novel 80 kDa DNA binding protein (telomere associated protein; Tap) in this process. Biochemical studies, yeast two hybrid analysis, and immunoprecipitation/immunodepletion experiments indicate that Tap binds tightly to specific sequence in 3' overhangs and also interacts with Tpg, bringing Tpg to telomere termini. Using DNA microarrays to analyze the chromosomes of tap mutant bacteria, we demonstrate that Tap ablation leads to telomere deletion, chromosome circularization, and amplification of subtelomeric DNA. Microarray-based chromosome mapping at single ORF resolution revealed common endpoints for independent deletions, identified amplified chromosomal ORFs adjacent to these endpoints, and quantified copy number of these ORFs. Sequence analysis confirmed chromosome circularization and revealed the insertion of adventitious DNA between joined chromosome ends. Our results show that Tap is required for linear DNA replication in Streptomyces and suggest that it functions to recruit and position Tpg at the telomeres of replication intermediates. They also identify hotspots for the telomeric deletions and subtelomeric DNA amplifications that accompany chromosome circularization.
In this webpage you can find the primary microarray data and a large picture of Figure 6.