1ny6
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Crystal structure of sigm54 activator (AAA+ ATPase) in the active state
OverviewOverview
Transcription by sigma54 RNA polymerase depends on activators that contain, ATPase domains of the AAA+ class. These activators, which are often, response regulators of two-component signal transduction systems, remodel, the polymerase so that it can form open complexes at promoters. Here, we, report the first crystal structures of the ATPase domain of an activator, the NtrC1 protein from the extreme thermophile Aquifex aeolicus. This, domain alone, which is active, crystallized as a ring-shaped heptamer. The, protein carrying both the ATPase and adjacent receiver domains, which is, inactive, crystallized as a dimer. In the inactive dimer, one residue, needed for catalysis is far from the active site, and extensive contacts, among the domains prevent oligomerization of the ATPase domain., Oligomerization, which completes the active site, depends on surfaces that, are buried in the dimer, and hence, on a rearrangement of the receiver, domains upon phosphorylation. A motif in the ATPase domain known to be, critical for coupling energy to remodeling of polymerase forms a novel, loop that projects from the middle of an alpha helix. The extended, structured loops from the subunits of the heptamer localize to a pore in, the center of the ring and form a surface that could contact sigma54.
About this StructureAbout this Structure
1NY6 is a Single protein structure of sequence from Aquifex aeolicus with ADP as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Regulation of the transcriptional activator NtrC1: structural studies of the regulatory and AAA+ ATPase domains., Lee SY, De La Torre A, Yan D, Kustu S, Nixon BT, Wemmer DE, Genes Dev. 2003 Oct 15;17(20):2552-63. PMID:14561776
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