Two surfaces on the histone chaperone Rtt106 mediate histone binding, replication, and silencing.

The histone chaperone Rtt106 binds histone H3 acetylated at lysine 56 (H3K56ac) and facilitates nucleosome assembly during several molecular processes. Both the structural basis of this modification-specific recognition and how this recognition informs Rtt106 function are presently unclear. Guided by our crystal structure of Rtt106, we identified two regions on its double-pleckstrin homology domain architecture that mediated histone binding.

Computational redesign of the SHV-1 beta-lactamase/beta-lactamase inhibitor protein interface.

Beta-lactamases are enzymes that catalyze the hydrolysis of beta-lactam antibiotics. beta-lactamase/beta-lactamase inhibitor protein (BLIP) complexes are emerging as a well characterized experimental model system for studying protein-protein interactions. BLIP is a 165 amino acid protein that inhibits several class A beta-lactamases with a wide range of affinities: picomolar affinity for K1; nanomolar affinity for TEM-1, SME-1, and BlaI; but only micromolar affinity for SHV-1 beta-lactamase.

Structure of the yeast histone H3-ASF1 interaction: implications for chaperone mechanism, species-specific interactions, and epigenetics.

Background: The histone H3/H4 chaperone Asf1 (anti-silencing function 1) is required for the establishment and maintenance of proper chromatin structure, as well as for genome stability in eukaryotes. Asf1 participates in both DNA replication-coupled (RC) and replication-independent (RI) histone deposition reactions in vitro and interacts with complexes responsible for both pathways in vivo. Asf1 is known to directly bind histone H3, however, high-resolution structural information about the geometry of this interaction was previously unknown.

Replication-independent histone deposition by the HIR complex and Asf1.

The orderly deposition of histones onto DNA is mediated by conserved assembly complexes, including chromatin assembly factor-1 (CAF-1) and the Hir proteins . CAF-1 and the Hir proteins operate in distinct but functionally overlapping histone deposition pathways in vivo . The Hir proteins and CAF-1 share a common partner, the highly conserved histone H3/H4 binding protein Asf1, which binds the middle subunit of CAF-1 as well as to Hir proteins .