Co-orientation of replication and transcription preserves genome integrity.
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In many bacteria, there is a genome-wide bias towards co-orientation of replication and transcription, with essential and/or highly-expressed genes further enriched co-directionally. We previously found that reversing this bias in the bacterium Bacillus subtilis slows replication elongation, and we proposed that this effect contributes to the evolutionary pressure selecting the transcription-replication co-orientation bias. This selection might have been based purely on selection for speedy replication; alternatively, the slowed replication might actually represent an average of individual replication-disruption events, each of which is counter-selected independently because genome integrity is selected. To differentiate these possibilities and define the precise forces driving this aspect of genome organization, we generated new strains with inversions either over approximately 1/4 of the chromosome or at ribosomal RNA (rRNA) operons. Applying mathematical analysis to genomic microarray snapshots, we found that replication rates vary dramatically within the inverted genome. Replication is moderately impeded throughout the inverted region, which results in a small but significant competitive disadvantage in minimal medium. Importantly, replication is strongly obstructed at inverted rRNA loci in rich medium. This obstruction results in disruption of DNA replication, activation of DNA damage responses, loss of genome integrity, and cell death. Our results strongly suggest that preservation of genome integrity drives the evolution of co-orientation of replication and transcription, a conserved feature of genome organization.
Published Version (Please cite this version)10.1371/journal.pgen.1000810
Publication InfoSrivatsan, Anjana; Tehranchi, Ashley; MacAlpine, David M; & Wang, Jue D (2010). Co-orientation of replication and transcription preserves genome integrity. PLoS Genet, 6(1). pp. e1000810. 10.1371/journal.pgen.1000810. Retrieved from https://hdl.handle.net/10161/4458.
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Professor of Pharmacology and Cancer Biology
Our laboratory is interested in understanding the mechanisms by which the molecular architecture of the chromosome regulates fundamental biological processes such as replication and transcription. Specifically, how are replication, transcription and chromatin modification coordinated on a genomic scale to maintain genomic stability? We are addressing this question by using genomic, computational and biochemical approaches in the model organism Drosophila melanogaster. DNA replica