View source for 2xg8


==Structural basis of gene regulation by protein PII: The crystal complex of PII and PipX from Synechococcus elongatus PCC 7942==
<StructureSection load='2xg8' size='340' side='right'caption='[[2xg8]], [[Resolution|resolution]] 3.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2xg8]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Synechococcus_elongatus_PCC_7942_=_FACHB-805 Synechococcus elongatus PCC 7942 = FACHB-805]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2XG8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2XG8 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.2&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2xg8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2xg8 OCA], [https://pdbe.org/2xg8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2xg8 RCSB], [https://www.ebi.ac.uk/pdbsum/2xg8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2xg8 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/GLNB_SYNE7 GLNB_SYNE7] P-II indirectly controls the transcription of the GS gene (glnA). P-II prevents NR-II-catalyzed conversion of NR-I to NR-I-phosphate, the transcriptional activator of glnA. When P-II is phosphorylated, these events are reversed. In nitrogen-limiting conditions, when the ratio of Gln to 2-ketoglutarate decreases, P-II is phosphorylated which allows the deadenylation of glutamine synthetase (GS), thus activating the enzyme.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/xg/2xg8_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2xg8 ConSurf].
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== Publication Abstract from PubMed ==
PII, an ancient and widespread signaling protein, transduces nitrogen/carbon/energy abundance signals through interactions with target proteins. We clarify structurally how PII regulates gene expression mediated by the transcription factor NtcA, the global nitrogen regulator of cyanobacteria, shedding light on NtcA structure and function and on how NtcA is activated by 2-oxoglutarate (2OG) and coactivated by the nonenzymatic PII target, protein PipX. We determine for the cyanobacteria Synechococcus elongatus the crystal structures of the PII-PipX and PipX-NtcA complexes and of NtcA in active and inactive conformations (respective resolutions, 3.2, 2.25, 2.3, and 3.05 A). The structures and the conclusions derived from them are consistent with the results of present and prior site-directed mutagenesis and functional studies. A tudor-like domain (TLD) makes up most of the PipX structure and mediates virtually all the contacts of PipX with PII and NtcA. In the PII-PipX complex, one PII trimer sequesters the TLDs of three PipX molecules between its body and its extended T loops, preventing PipX activation of NtcA. Changes in T loop conformation triggered by 2OG explain PII-PipX dissociation when 2OG is bound. The structure of active dimeric NtcA closely resembles that of the active cAMP receptor protein (CRP). This strongly suggests that with these proteins DNA binding, transcription activation, and allosteric regulation occur by common mechanisms, although the effectors are different. The PipX-NtcA complex consists of one active NtcA dimer and two PipX monomers. PipX coactivates NtcA by stabilizing its active conformation and by possibly helping recruit RNA polymerase but not by providing extra DNA contacts.

Structural basis for the regulation of NtcA-dependent transcription by proteins PipX and PII.,Llacer JL, Espinosa J, Castells MA, Contreras A, Forchhammer K, Rubio V Proc Natl Acad Sci U S A. 2010 Aug 17. PMID:20716687<ref>PMID:20716687</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Synechococcus elongatus PCC 7942 = FACHB-805]]
[[Category: Llacer JL]]
[[Category: Rubio V]]