View source for 4b27


==Trp RNA-binding attenuation protein: modifying symmetry and stability of a circular oligomer==
<StructureSection load='4b27' size='340' side='right'caption='[[4b27]], [[Resolution|resolution]] 2.72&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4b27]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/"vibrio_subtilis"_ehrenberg_1835 "vibrio subtilis" ehrenberg 1835]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4B27 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4B27 FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=TRP:TRYPTOPHAN'>TRP</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1wap|1wap]], [[3zzq|3zzq]]</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4b27 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4b27 OCA], [http://pdbe.org/4b27 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4b27 RCSB], [http://www.ebi.ac.uk/pdbsum/4b27 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4b27 ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/MTRB_BACSU MTRB_BACSU]] Required for transcription attenuation control in the Trp operon. This trans-acting factor seems to recognize a 10 bases nucleotide sequence in the Trp leader transcript causing transcription termination. Binds the leader RNA only in presence of L-tryptophan.<ref>PMID:1551827</ref>  
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
BACKGROUND: Subunit number is amongst the most important structural parameters that determine size, symmetry and geometry of a circular protein oligomer. The L-tryptophan biosynthesis regulator, TRAP, present in several Bacilli, is a good model system for investigating determinants of the oligomeric state. A short segment of C-terminal residues defines whether TRAP forms an 11-mer or 12-mer assembly. To understand which oligomeric state is more stable, we examine the stability of several wild type and mutant TRAP proteins. METHODOLOGY/PRINCIPAL FINDINGS: Among the wild type B. stearothermophilus, B. halodurans and B. subtilis TRAP, we find that the former is the most stable whilst the latter is the least. Thermal stability of all TRAP is shown to increase with L-tryptophan concentration. We also find that mutant TRAP molecules that are truncated at the C-terminus - and hence induced to form 12-mers, distinct from their 11-mer wild type counterparts - have increased melting temperatures. We show that the same effect can be achieved by a point mutation S72N at a subunit interface, which leads to exclusion of C-terminal residues from the interface. Our findings are supported by dye-based scanning fluorimetry, CD spectroscopy, and by crystal structure and mass spectrometry analysis of the B. subtilis S72N TRAP. CONCLUSIONS/SIGNIFICANCE: We conclude that the oligomeric state of a circular protein can be changed by introducing a point mutation at a subunit interface. Exclusion (or deletion) of the C-terminus from the subunit interface has a major impact on properties of TRAP oligomers, making them more stable, and we argue that the cause of these changes is the altered oligomeric state. The more stable TRAP oligomers could be used in potential applications of TRAP in bionanotechnology.

Trp RNA-Binding Attenuation Protein: Modifying Symmetry and Stability of a Circular Oligomer.,Bayfield OW, Chen CS, Patterson AR, Luan W, Smits C, Gollnick P, Antson AA PLoS One. 2012;7(9):e44309. Epub 2012 Sep 6. PMID:22970197<ref>PMID:22970197</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4b27" style="background-color:#fffaf0;"></div>

==See Also==
*[[Tryptophan RNA-binding attenuation protein|Tryptophan RNA-binding attenuation protein]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Vibrio subtilis ehrenberg 1835]]
[[Category: Large Structures]]
[[Category: Antson, A A]]
[[Category: Bayfield, O W]]
[[Category: Chen, C]]
[[Category: Gollnick, P]]
[[Category: Luan, W]]
[[Category: Patterson, A R]]
[[Category: Smits, C]]
[[Category: Protein engineering]]
[[Category: Thermofluor]]
[[Category: Transcription]]
[[Category: Transcription regulation]]