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Journal of molecular biology (1)
The EMBO Journal (1)
Sundaramoorthy, Ramasubramanian (3)
Owen-Hughes, Tom (2)
Fyfe, Paul K. (1)
Hunter, William N. (1)
Martin, David (1)
Narlikar, Geeta J. (1)
Ryan, Daniel P (1)
Singh, Vijender (1)
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Mechanisms and Functions of ATP-Dependent Chromatin-Remodeling Enzymes
Narlikar, Geeta J.
Chromatin provides both a means to accommodate a large amount of genetic material in a small space and a means to package the same genetic material in different chromatin states. Transitions between chromatin states are enabled by chromatin-remodeling ATPases, which catalyze a diverse range of structural transformations. Biochemical evidence over the last two decades suggests that chromatin-remodeling activities may have emerged by adaptation of ancient DNA translocases to respond to specific features of chromatin. Here, we discuss such evidence and also relate mechanistic insights to our understanding of how chromatin-remodeling enzymes enable different in vivo processes.
Structure of Staphylococcus aureus EsxA suggests a contribution to virulence by action as a transport chaperone and/or adaptor protein
Fyfe, Paul K.
Hunter, William N.
Journal of molecular biology
Staphylococcus aureus pathogenesis depends on a specialized protein secretion system, ESX-1, that delivers a range of virulence factors to assist infectivity. We report the characterization of two such factors, EsxA and EsxB; small acidic dimeric proteins carrying a distinctive WXG motif. EsxA crystallized in triclinic and monoclinic forms and high-resolution structures were determined. The asymmetric unit of each crystal form is a dimer. The EsxA subunit forms an elongated cylindrical structure created from side-by-side α-helices linked with a hairpin bend formed by the WXG motif. Approximately 25% of the solvent accessible surface area of each subunit is involved in interactions, predominantly hydrophobic, with the partner subunit. Secondary structure predictions suggest that EsxB displays a similar structure. The WXG motif helps to create a shallow cleft at each end of the dimer, forming a short β-sheet-like feature with an N-terminal segment of the partner subunit. Structural and sequence comparisons, exploiting biological data on related proteins found in Mycobacteria tuberculosis suggest that this family of proteins may contribute to pathogenesis by transporting protein cargo through the ESX-1 system exploiting a C-terminal secretion signal and / or are capable of acting as adaptor proteins to facilitate interactions with host receptor proteins.
adaptor protein; chaperone; helical bundle; secretion system; virulence factor
The DNA-binding domain of the Chd1 chromatin-remodelling enzyme contains SANT and SLIDE domains
Ryan, Daniel P
The EMBO Journal
The large diversity in nucleosome-remodelling enzymes evokes great interest in unveiling common mechanistic themes in remodelling reactions. Here, the C-terminus of Chd1 contains a functionally important DNA-binding domain unexpectedly similar to the SANT and SLIDE domains in the ISWI ATPase.
The ATP-dependent chromatin-remodelling enzyme Chd1 is a 168-kDa protein consisting of a double chromodomain, Snf2-related ATPase domain, and a C-terminal DNA-binding domain. Here, we show the DNA-binding domain is required for Saccharomyces cerevisiae Chd1 to bind and remodel nucleosomes. The crystal structure of this domain reveals the presence of structural homology to SANT and SLIDE domains previously identified in ISWI remodelling enzymes. The presence of these domains in ISWI and Chd1 chromatin-remodelling enzymes may provide a means of efficiently harnessing the action of the Snf2-related ATPase domain for the purpose of nucleosome spacing and provide an explanation for partial redundancy between these proteins. Site directed mutagenesis was used to identify residues important for DNA binding and generate a model describing the interaction of this domain with DNA. Through inclusion of Chd1 sequences in homology searches SLIDE domains were identified in CHD6–9 proteins. Point mutations to conserved amino acids within the human CHD7 SLIDE domain have been identified in patients with CHARGE syndrome.
Chd1; DNA binding; nucleosomes; SANT; SLIDE
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