Dataset Information

Conformational preference of 'C?NN' short peptide motif towards recognition of anions.

ABSTRACT: Among several 'anion binding motifs', the recently described 'C(?)NN' motif occurring in the loop regions preceding a helix, is conserved through evolution both in sequence and its conformation. To establish the significance of the conserved sequence and their intrinsic affinity for anions, a series of peptides containing the naturally occurring 'C(?)NN' motif at the N-terminus of a designed helix, have been modeled and studied in a context free system using computational techniques. Appearance of a single interacting site with negative binding free-energy for both the sulfate and phosphate ions, as evidenced in docking experiments, establishes that the 'C(?)NN' segment has an intrinsic affinity for anions. Molecular Dynamics (MD) simulation studies reveal that interaction with anion triggers a conformational switch from non-helical to helical state at the 'C(?)NN' segment, which extends the length of the anchoring-helix by one turn at the N-terminus. Computational experiments substantiate the significance of sequence/structural context and justify the conserved nature of the 'C(?)NN' sequence for anion recognition through "local" interaction.

SUBMITTER: Sheet T

PROVIDER: S-EPMC3596363 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Conformational preference of 'CαNN' short peptide motif towards recognition of anions.

Sheet Tridip T Supakar Subhrangshu S Banerjee Raja R

PloS one 20130313 3

Among several 'anion binding motifs', the recently described 'C(α)NN' motif occurring in the loop regions preceding a helix, is conserved through evolution both in sequence and its conformation. To establish the significance of the conserved sequence and their intrinsic affinity for anions, a series of peptides containing the naturally occurring 'C(α)NN' motif at the N-terminus of a designed helix, have been modeled and studied in a context free system using computational techniques. Appearance ...[more]

PMID: 23516403

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Project description:C hordein, a storage protein from barley grains, has an Mr of about 53,000, and consists predominantly of repeated octapeptides with a consensus sequence of Pro-Gln-Gln-Pro-Phe-Pro-Gln-Gln. Previously reported hydrodynamic and c.d. studies indicate the presence of beta-turns, the repetitive nature of which may lead to the formation of a loose spiral. In order to study these turns we have compared the structures of a synthetic peptide corresponding to the consensus repeat motif and total C hordein by using c.d. and Fourier-transform i.r. spectroscopy. The synthetic peptide exhibited spectra typical of beta I/III reverse turns when dissolved in trifluoroethanol at 22 degrees C and in water at 70 degrees C, but 'random-coil'-like spectra in water at 22 degrees C. The whole protein also showed increases in beta I/III reverse turns when dissolved in increasing concentrations of trifluoroethanol (50-100%, v/v) or heated in ethanol/water (7:3, v/v). Two cryogenic solvent systems were used to determine the c.d. spectra of the peptide and protein at temperatures down to -100 degrees C. Methanol/glycerol (9:1, v/v) and ethanediol/water (2:1, v/v) were selected as analogues of trifluoroethanol/water and water respectively. The peptide exhibited beta I/III-reverse-turn and 'random-coil'-like spectra in methanol/glycerol and ethanediol/water respectively at 22 degrees C, but a spectrum similar to that of a poly-L-proline II helix in both solvents at -100 degrees C. Similarly the proportion of this spectral type also increased when the whole protein was cooled in both solvents. These results indicate that a poly-L-proline II conformation at low temperatures is in equilibrium with a beta I/III-turn-rich conformation at higher temperatures. The latter conformation is also favoured in solvents of low dielectric constant such as trifluoroethanol. The 'random-coil'-like spectra exhibited by the protein and peptide in high-dielectric-constant solvents at room temperature may result from a mixture of the two conformations rather than from the random-coil state.

Dataset Information

Conformational preference of 'C?NN' short peptide motif towards recognition of anions.

Publications

Conformational preference of 'CαNN' short peptide motif towards recognition of anions.

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