Scheduled Seminars on 10/14/2010

Ariel Weinberger at 11:00  Edit  Reschedule  Delete
Affiliation: University of California at Berkeley
Host: Makarova

Modeling Predicts Ancestral Viral Blooms Drive Old End Uniformity In CRISPR Loci
A major barrier to demonstrating virus-host coevolution in microbial systems is that most microbes are uncultivable. Metagenomic snapshots of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), a newly discovered microbial adaptive immune system against viruses and plasmids, offer cultivation-independent serial recordings of immunogenic, virus-derived ‘spacers.’ We present a population-scale mathematical model reconstructing the dynamics of CRISPR-driven virus-host coevolution from metagenomic snapshots of CRISPR loci across natural and laboratory populations. Our computationally evolved CRISPR patterns predict experimentally-measured loci, showing how virus-host coevolution drives the strikingly consistent pattern of old-end clonality and new-end diversity measured across microbial populations. Simulations predict that CRISPR old ends are conserved against metagenomically-recorded blooms of ancestral viral elements. CRISPR may be the first immune system tuned against persistent, temperate viruses, suggesting temperate phage therapy to select for CRISPR-laden microbes that block plasmid-borne pathogenicity and antibiotic resistance.


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