MtSnf2
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(New page: ==Myceliophthora thermophila Sucrose Non-Fermenting 2== <StructureSection load='1stp' size='340' side='right' caption='Caption for this structure' scene=''> The crystal structure of Snf2 (...)
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Revision as of 11:50, 30 November 2025
Myceliophthora thermophila Sucrose Non-Fermenting 2
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Mutations in genes that encode proteins of the SWI/SNF complex, called BAF complex in mammals, cause a spectrum of disorders that ranges from syndromic intellectual disability to Coffin-Siris syndrome (CSS) to Nicolaides-Baraitser syndrome (NCBRS).
Structural highlights
The DNA binding sites of MtSnf2 remain fully exposed even in its inactive state suggesting that the protein maintains a poised state for helicase activity with the ATP-ase site regulated.
The catalytic core of MtSnf2 is structurally divided into two major portions: Lobe 1 and Lobe 2. Lobe 1 consists of the post-HSA (helicase/SANT-associated) domain and the first RecA-like core domain (Core 1). Lobe 2 contains the second RecA-like core domain (Core 2) and the C-terminal SnAc domain.
The structure is held in an inactive state by the direct stacking and interaction between the two RecA-like core domains. This interaction twists the essential ATP-binding motifs, Motif I (P loop) and Motif VI (arginine fingers), toward opposite directions, effectively blocking their direct contact and explaining the protein's inactivity in the ground state. The primary interaction occurs at the interface where Core 1, via the &alpha 5 helix, makes hydrophobic contact with V797 from the &beta 7 of the Core 2 domain, burying a solvent-inaccessible surface area. Perturbing this interaction, such as with the T616D V797D double mutation, significantly increases the basal ATPase activity by a factor of 5. Additionally, the post-HSA domain binds to Core 1, specifically interacting with the last helix, which is redefined as the suppressor helix(suppH). Finally, the C-terminal SnAc domain meanders at the surface of Core 2, covering a large area (over 2,300 angstrom.sq.), and plays a key role in stabilizing the Core 2 domain while making little contact with Core 1. This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.
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