2j5a
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FOLDING OF S6 STRUCTURES WITH DIVERGENT AMINO-ACID COMPOSITION: PATHWAY FLEXIBILITY WITHIN PARTLY OVERLAPPING FOLDONS
OverviewOverview
Studies of circular permutants have demonstrated that the folding reaction, of S6 from Thermus thermophilus (S6(T)) is malleable and responds in an, ordered manner to changes of the sequence separation between interacting, residues: the S6(T) permutants retain a common nucleation pattern in the, form of a two-strand-helix motif that can be recruited from different, parts of the structure. To further test the robustness of the, two-strand-helix nucleus we have here determined the crystal structure and, folding reaction of an evolutionary divergent S6 protein from the, hyperthermophilic bacterium Aquifex aeolicus (S6(A)). Although the overall, topology of S6(A) is very similar to that of S6(T) the architecture of the, hydrophobic core is radically different by containing a large proportion, of stacked Phe side-chains. Despite this disparate core composition, the, folding rate constant and the kinetic m values of S6(A) are identical to, those of S6(T). The folding nucleus of S6(A) is also found to retain the, characteristic two-strand-helix motif of the S6(T) permutants, but with a, new structural emphasis. The results suggest that the protein folding, reaction is linked to topology only in the sense that the native-state, topology determines the repertoire of accessible nucleation motifs. If the, native structure allows several equivalent ways of recruiting a productive, nucleus the folding reaction is free to redistribute within these, topological constraints.
About this StructureAbout this Structure
2J5A is a Single protein structure of sequence from Aquifex aeolicus with as ligand. Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Folding of S6 structures with divergent amino acid composition: pathway flexibility within partly overlapping foldons., Olofsson M, Hansson S, Hedberg L, Logan DT, Oliveberg M, J Mol Biol. 2007 Jan 5;365(1):237-48. Epub 2006 Sep 12. PMID:17056063
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