The rules of evolution are universal to all of life. Like
eukaryotic cells, prokaryotic life must also defend itself
against parasitic infection. Historically, our appreciation
for the prokaryotic 'immune system' has been limited to
restriction/modification systems. However, more recent
studies suggest that prokaryotic life may have evolved a more
sophisticated RNAi-like immune system. CRISPR elements (Clusters
of Regularly Interspaced Short Palindromic Repeats) are common
features in prokaryotic genomes and a distinct signature of this
system. Upon viral challenge, these repetitive elements readily
assimilate snippets of new sequences derived from the virus,
which then strongly correlates with a phage-resistance phenotype.
Comparative genomic analysis has identified a variable cassette
of ~25 gene families that are commonly associated with CRISPRs.
Many of these CRISPR associated (cas) genes have recently been
assigned putative functional roles analogous to those involved
in the eukaryotic RNAi-based gene regulation system. The aim
of my research is to biochemically identify and structurally
characterize the components of this immune system.
