Histon H3 tail positioning and acetylation by the c-Myb but not the v-Myb DNA-binding SANT domain (Gene Dev, 2005, 19:2447-2457)

報告日期: 2006/03/28
報告時間: 15:10/16:00
報告學生: 王怡婷
講評老師: 洪建中


Histone H3 tail positioning and

acetylation by the c-Myb but not the v-Myb DNA-binding SANT domain



Date: 2006/3/28                Room: 602

Speaker: Yi-Ting Wang

Commentator: Jan Jong Hung


The Myb-related proteins are a large and growing family of transcription factors with a unique DNA binding domain, first identified in the v-Myb transforming protein made by the AMV (Avian Myeloblastosis Virus), and the cellular predecessor, c-myb. The v-Myb transforming proteins they encode are truncated, mutated and constitutively expressed version of c-Myb, the protein product of the c-myb protooncogene and harbor 11 amino acid substitutions relative to c-Myb. The hallmark of all Myb-related proteins is their unique DNA binding domain (DBD) and consists of an unusual structure of three tandemly repeats termed R1, R2 and R3, each arranged in a helix-turn-helix motif. The Myb-DBD carry the architectural signature of the chromatin-interacting SANT domain, previously identified in several chromatin regulatory proteins (e.g., Swi3, Ada2 and NcoR). c-Myb protein cooperates with other transcription factors in the transcriptional trans-activation of target promoters, such as p300/CBP and C/EBP beta. In this study, the authors demonstrate the cMyb-DBD bind to the N-terminal histone tails of H3 and position it for acetylation. Binding of the cMyb-DBD to histones is specific for H3 and H3.3 and is a prerequisite for the activation of of dirrerentiation genes. The three mutations in v-myb-DBD eliminate the interaction with H3 and acetylation of H3 tail. Taken together, cMyb-DBD carries a function that is characteristic for SANT domain proteins involved in histone acetylation and that v-Myb is deficient in catalyzing this chromatin modification, linking defective chromatin remodeling by v-Myb to its tumorigenic potential.


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