2cvr

[[Image:2cvr.gif|left|200px]]<br /><applet load="2cvr" size="450" color="white" frame="true" align="right" spinBox="true"

caption="2cvr" />

'''NMR solution structure of sso7d mutant, K12L, 12 conformers'''<br />

==Overview==

Sso7d is a basic 7-kDa DNA-binding protein from Sulfolobus solfataricus, also endowed with ribonuclease activity. The protein consists of a, double-stranded antiparallel beta-sheet, onto which an orthogonal, triple-stranded antiparallel beta-sheet is packed, and of a small helical, stretch at the C-terminus. Furthermore, the two beta-sheets enclose an, aromatic cluster displaying a fishbone geometry. We previously cloned the, Sso7d-encoding gene, expressed it in Escherichia coli, and produced, several single-point mutants, either of residues located in the, hydrophobic core or of Trp23, which is exposed to the solvent and plays a, major role in DNA binding. The mutation F31A was dramatically, destabilizing, with a loss in thermo- and piezostabilities by at least 27, K and 10 kbar, respectively. Here, we report the solution structure of the, F31A mutant, which was determined by NMR spectroscopy using 744 distance, constraints obtained from analysis of multidimensional spectra in, conjunction with simulated annealing protocols. The most remarkable, finding is the change in orientation of the Trp23 side chain, which in the, wild type is completely exposed to the solvent, whereas in the mutant is, largely buried in the aromatic cluster. This prevents the formation of a, cavity in the hydrophobic core of the mutant, which would arise in the, absence of structural rearrangements. We found additional changes produced, by the mutation, notably a strong distortion in the beta-sheets with loss, in several hydrogen bonds, increased flexibility of some stretches of the, backbone, and some local strains. On one hand, these features may justify, the dramatic destabilization provoked by the mutation; on the other hand, they highlight the crucial role of the hydrophobic core in protein, stability. To the best of our knowledge, no similar rearrangement has been, so far described as a result of a single-point mutation.

 

==About this Structure==

2CVR is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sulfolobus_solfataricus Sulfolobus solfataricus]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2CVR OCA].

 

==Reference==

A single-point mutation in the extreme heat- and pressure-resistant sso7d protein from sulfolobus solfataricus leads to a major rearrangement of the hydrophobic core., Consonni R, Santomo L, Fusi P, Tortora P, Zetta L, Biochemistry. 1999 Sep 28;38(39):12709-17. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10504241 10504241]

[[Category: Single protein]]

[[Category: Sulfolobus solfataricus]]

[[Category: Alberti, E.]]

[[Category: Arosio, I.]]

[[Category: Consonni, R.]]

[[Category: Fusi, P.]]

[[Category: Recca, T.]]

[[Category: Zetta, L.]]

[[Category: dna-binding protein]]

[[Category: nmr]]

[[Category: single point mutation]]

[[Category: sulfolobus solfataricus]]

[[Category: thermostable protein]]