1ny5

[[Image:1ny5.gif|left|200px]]<br /><applet load="1ny5" size="350" color="white" frame="true" align="right" spinBox="true"

caption="1ny5, resolution 2.40&Aring;" />

'''Crystal structure of sigm54 activator (AAA+ ATPase) in the inactive state'''<br />

==Overview==

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 Structure==

1NY5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aquifex_aeolicus Aquifex aeolicus] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=ADP:'>ADP</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NY5 OCA].

 

==Reference==

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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=14561776 14561776]

[[Category: Single protein]]

[[Category: Kustu, S.]]

[[Category: Lee, S Y.]]

[[Category: Nixon, B T.]]

[[Category: Torre, A de la.]]

[[Category: Wemmer, D E.]]

[[Category: ADP]]