Bacteriophages outnumber bacterial prey by about 10-fold. The estimated ≥10^30 bacteriophages (phages) on Earth cause infections at a rate of 10^25 per second. To contend with this extreme selection pressure, bacteria have evolved varied modes of defence against phages and other mobile genetic elements. Well-established examples of defence systems include restriction–modification (R–M), abortive infection, and CRISPR-Cas systems. Recent comparative genomic analyses have demonstrated how diverse defence systems also commonly cluster into ‘defence islands’. It has been postulated that WYL-domain containing proteins act as ligand-binding regulators of phage defence system expression. WYL-domains (named after three conserved amino acids), are only found in prokaryotes and are part of the Sm/SH3 superfold family, which is itself subsumed by the larger ‘small β-barrel’ family. The Escherichia WYL-domain containing protein, BrxR, was hypothesized to act as a transcriptional regulator being the first member of a large family of transcriptional regulators. BrxR-family homologues are widely associated with diverse phage defence systems and islands. Here you can see the structure of the dimeric BrxR protein from Escherichia fergusonii ATCC 35469, determined by X-ray diffraction (PDB code: 7QFZ)
#molecularart ... #immolecular ... #phage ... #defense ... #cluster ... #BrxR ... #WYL ... #xray
Structure of BrxR protein rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #phage ... #defense ... #cluster ... #BrxR ... #WYL ... #xray
Structure of BrxR protein rendered with @proteinimaging and depicted with @corelphotopaint
