3uk6 | pdb_00003uk6
Crystal Structure of the Tip48 (Tip49b) hexamer
Structural highlights
Function[RUVB2_HUMAN] Possesses single-stranded DNA-stimulated ATPase and ATP-dependent DNA helicase (5' to 3') activity; hexamerization is thought to be critical for ATP hydrolysis and adjacent subunits in the ring-like structure contribute to the ATPase activity.[1] Component of the NuA4 histone acetyltransferase complex which is involved in transcriptional activation of select genes principally by acetylation of nucleosomal histones H4 and H2A. This modification may both alter nucleosome - DNA interactions and promote interaction of the modified histones with other proteins which positively regulate transcription. This complex may be required for the activation of transcriptional programs associated with oncogene and proto-oncogene mediated growth induction, tumor suppressor mediated growth arrest and replicative senescence, apoptosis, and DNA repair. The NuA4 complex ATPase and helicase activities seem to be, at least in part, contributed by the association of RUVBL1 and RUVBL2 with EP400. NuA4 may also play a direct role in DNA repair when recruited to sites of DNA damage.[2] Proposed core component of the chromatin remodeling INO80 complex which is involved in transcriptional regulation, DNA replication and probably DNA repair.[3] Plays an essential role in oncogenic transformation by MYC and also modulates transcriptional activation by the LEF1/TCF1-CTNNB1 complex. May also inhibit the transcriptional activity of ATF2.[4] Publication Abstract from PubMedThe TIP49a and TIP49b proteins belong to the family of AAA+ ATPases and play essential roles in vital processes such as transcription, DNA repair, snoRNP biogenesis, and chromatin remodeling. We report the crystal structure of a TIP49b hexamer and the comparative analysis of large-scale conformational flexibility of TIP49a, TIP49b, and TIP49a/TIP49b complexes using molecular modeling and molecular dynamics simulations in a water environment. Our results establish key principles of domain mobility that affect protein conformation and biochemical properties, including a mechanistic basis for the downregulation of ATPase activity upon protein hexamerization. These approaches, applied to the lik-TIP49b mutant reported to possess enhanced DNA-independent ATPase activity, help explain how a three-amino acid insertion remotely affects the structure and conformational dynamics of the ATP binding and hydrolysis pocket while uncoupling ATP hydrolysis from DNA binding. This might be similar to the effects of conformations adopted by TIP49 heterohexamers. Large-Scale Conformational Flexibility Determines the Properties of AAA+ TIP49 ATPases.,Petukhov M, Dagkessamanskaja A, Bommer M, Barrett T, Tsaneva I, Yakimov A, Queval R, Shvetsov A, Khodorkovskiy M, Kas E, Grigoriev M Structure. 2012 Jun 27. PMID:22748767[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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