2e50 | pdb_00002e50
Crystal structure of SET/TAF-1beta/INHAT
Structural highlights
Disease[SET_HUMAN] Note=A chromosomal aberration involving SET is found in some cases of acute undifferentiated leukemia (AUL). Translocation t(6;9)(q21;q34.1) with NUP214/CAN. Function[SET_HUMAN] Multitasking protein, involved in apoptosis, transcription, nucleosome assembly and histone chaperoning. Isoform 2 anti-apoptotic activity is mediated by inhibition of the GZMA-activated DNase, NME1. In the course of cytotoxic T-lymphocyte (CTL)-induced apoptosis, GZMA cleaves SET, disrupting its binding to NME1 and releasing NME1 inhibition. Isoform 1 and isoform 2 are potent inhibitors of protein phosphatase 2A. Isoform 1 and isoform 2 inhibit EP300/CREBBP and PCAF-mediated acetylation of histones (HAT) and nucleosomes, most probably by masking the accessibility of lysines of histones to the acetylases. The predominant target for inhibition is histone H4. HAT inhibition leads to silencing of HAT-dependent transcription and prevents active demethylation of DNA. Both isoforms stimulate DNA replication of the adenovirus genome complexed with viral core proteins; however, isoform 2 specific activity is higher. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHistone chaperones assemble and disassemble nucleosomes in an ATP-independent manner and thus regulate the most fundamental step in the alteration of chromatin structure. The molecular mechanisms underlying histone chaperone activity remain unclear. To gain insights into these mechanisms, we solved the crystal structure of the functional domain of SET/TAF-Ibeta/INHAT at a resolution of 2.3 A. We found that SET/TAF-Ibeta/INHAT formed a dimer that assumed a "headphone"-like structure. Each subunit of the SET/TAF-Ibeta/INHAT dimer consisted of an N terminus, a backbone helix, and an "earmuff" domain. It resembles the structure of the related protein NAP-1. Comparison of the crystal structures of SET/TAF-Ibeta/INHAT and NAP-1 revealed that the two proteins were folded similarly except for an inserted helix. However, their backbone helices were shaped differently, and the relative dispositions of the backbone helix and the earmuff domain between the two proteins differed by approximately 40 degrees . Our biochemical analyses of mutants revealed that the region of SET/TAF-Ibeta/INHAT that is engaged in histone chaperone activity is the bottom surface of the earmuff domain, because this surface bound both core histones and double-stranded DNA. This overlap or closeness of the activity surface and the binding surfaces suggests that the specific association among SET/TAF-Ibeta/INHAT, core histones, and double-stranded DNA is requisite for histone chaperone activity. These findings provide insights into the possible mechanisms by which histone chaperones assemble and disassemble nucleosome structures. Relationship between the structure of SET/TAF-Ibeta/INHAT and its histone chaperone activity.,Muto S, Senda M, Akai Y, Sato L, Suzuki T, Nagai R, Senda T, Horikoshi M Proc Natl Acad Sci U S A. 2007 Mar 13;104(11):4285-90. Epub 2007 Mar 6. PMID:17360516[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. ReferencesContents | ||||||||||||||||||||
