title: Structure and mechanism of the Swi2/Snf2 remodeller Mot1 in complex with its substrate TBP.
abstract: Swi2/Snf2-type ATPases regulate genome-associated processes such as transcription, replication and repair by catalysing the disruption, assembly or remodelling of nucleosomes or other protein-DNA complexes. It has been suggested that ATP-driven motor activity along DNA disrupts target protein-DNA interactions in the remodelling reaction. However, the complex and highly specific remodelling reactions are poorly understood, mostly because of a lack of high-resolution structural information about how remodellers bind to their substrate proteins. Mot1 (modifier of transcription 1 in Saccharomyces cerevisiae, denoted BTAF1 in humans) is a Swi2/Snf2 enzyme that specifically displaces the TATA box binding protein (TBP) from the promoter DNA and regulates transcription globally by generating a highly dynamic TBP pool in the cell. As a Swi2/Snf2 enzyme that functions as a single polypeptide and interacts with a relatively simple substrate, Mot1 offers an ideal system from which to gain a better understanding of this important enzyme family. To reveal how Mot1 specifically disrupts TBP-DNA complexes, we combined crystal and electron microscopy structures of Mot1-TBP from Encephalitozoon cuniculi with biochemical studies. Here we show that Mot1 wraps around TBP and seems to act like a bottle opener: a spring-like array of 16 HEAT (huntingtin, elongation factor 3, protein phosphatase 2A and lipid kinase TOR) repeats grips the DNA-distal side of TBP via loop insertions, and the Swi2/Snf2 domain binds to upstream DNA, positioned to weaken the TBP-DNA interaction by DNA translocation. A 'latch' subsequently blocks the DNA-binding groove of TBP, acting as a chaperone to prevent DNA re-association and ensure efficient promoter clearance. This work shows how a remodelling enzyme can combine both motor and chaperone activities to achieve functional specificity using a conserved Swi2/Snf2 translocase.
authors: Department of Biochemistry, Ludwig-Maximilians University, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
authors: Petra
authors: P
authors: Wollmann
authors: Sheng
authors: S
authors: Cui
authors: Ramya
authors: R
authors: Viswanathan
authors: Otto
authors: O
authors: Berninghausen
authors: Melissa N
authors: MN
authors: Wells
authors: Manuela
authors: M
authors: Moldt
authors: Gregor
authors: G
authors: Witte
authors: Agata
authors: A
authors: Butryn
authors: Petra
authors: P
authors: Wendler
authors: Roland
authors: R
authors: Beckmann
authors: David T
authors: DT
authors: Auble
authors: Karl-Peter
authors: KP
authors: Hopfner
mesh_terms: D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D009670:Encephalitozoon cuniculi / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008954:Models, Biological; D008958:Models, Molecular; D011401:Promoter Regions, Genetic / Q000235:genetics; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D035181:TATA-Box Binding Protein / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D035581:Transcription Factor TFIIB / Q000737:chemistry / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D035181:TATA-Box Binding Protein; D035581:Transcription Factor TFIIB; D004247:DNA