Crystal structure and biochemical investigations reveal novel mode of substrate selectivity and illuminate substrate inhibition and allostericity in a subfamily of Xaa-Pro dipeptidases.

Xaa-Pro dipeptidase (XPD) catalyzes hydrolysis of iminopeptide bond in dipeptides containing trans-proline as a second residue. XPDs are found in all living organisms and are believed to play an essential role in proline metabolism. Here, we report crystal structures and extensive enzymatic studies of XPD from Xanthomonas campestris (XPDxc), the first such comprehensive study of a bacterial XPD.

Crystal structure and dynamics of Spt16N-domain of FACT complex from Cicer arietinum.

The facilitates chromatin transcription (FACT) complex, a heterodimer of SSRP1 and Spt16 proteins, is an essential histone chaperone that transiently reorganizes nucleosomes during transcription, replication and repair. N-terminal domain of Spt16 subunit (Spt16N) is strictly conserved in all the known Spt16 orthologs. Genetic studies in yeast have revealed a partially redundant role of Spt16N for the FACT functionality.