This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.PrgX, a key player in controlling conjugation induced by the peptide pheromone cCF10 in Enterococcus faecalis, is the cytoplasmic receptor for the cCF10 peptide pheromone and has been shown to bind to two sequences in the intergenic region of pCF10 between prgX and prgQ (the prgQ operon encodes the conjugative transfer functions of pCF10). We have solved the crystal structures of PrgX and PrgX/cCF10 complex. We proposed that PrgX functions as a tetramer in vivo from our PrgX crystal structures. The structure of the pheromone-PrgX complex reveals that pheromone binds in the cleft of the central dimerization domain, causes the C-terminal regulatory domain rotates about 120 and thus disrupts the PrgX tetramer. The results have been published in PNAS in 2005. cCF10 is a heptapeptide. To study the effects of different sequence on the cCF10 biological function, different mutations of cCF10 have been constructed and co-crystallized with PrgX. These crystals, like the PrgX/cCF10 crystals, all have a very long unit cell dimension (othorombic, a=71 , b=84 , c=280 ) and large mosaicity (>1.5 ). Therefore, a strong and well-focused thin beam is essential for having good data for these crystals.
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