4b27

Trp RNA-binding attenuation protein: modifying symmetry and stability of a circular oligomer

spinqualitylabelsall models 4b27, resolution 2.72Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4b27 is a 6 chain structure with sequence from "vibrio_subtilis"_ehrenberg_1835 "vibrio subtilis" ehrenberg 1835. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: TRP Related: 1wap, 3zzq Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Tryptophan RNA-binding attenuation protein

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