Evaluation of the energetic contribution of interhelical coulombic interactions for coiled coil helix orientation specificity1 Export

@article{citeulike:5624688, abstract = {Coiled coils are formed by two or more α-helices that align in a parallel or an antiparallel relative orientation. The factors that determine a preference for a given relative helix orientation are incompletely understood. The helix orientation preference for the designed coiled coil, Acid-a1-Base-a1, was measured previously. This model system therefore provides a means for the experimental determination of the energetic contribution of a variety of interactions to helix orientation specificity. The antiparallel preference for Acid-a1-Base-a1 is imparted by a single buried polar interaction. Interhelical Coulombic interactions between residues at the e and g positions have been proposed to influence helix orientation preference. In the Acid-a1-Base-a1 heterodimer, potentially attractive Coulombic interactions are expected in both orientations. To determine the energetic consequences of Coulombic interactions for helix orientation preference, we have positioned a single charged residue in each peptide such that exclusively favorable interhelical Coulombic interactions can occur only in the parallel orientation. In contrast, two potentially repulsive interactions are expected in the antiparallel orientation. Because the buried polar interaction can occur only in the antiparallel orientation, interhelical Coulombic interactions favor the parallel orientation and the potential to form a buried polar interaction favors the antiparallel orientation. We find no clear preference for an antiparallel orientation in the resulting heterodimer, Acid-K e -Base-E g , suggesting that interhelical Coulombic interactions and a buried polar interaction are of approximately equal importance for helix orientation specificity. Stability measurements indicate that maintenance of all favorable electrostatic interactions and/or avoidance of two potentially repulsive interactions contributes approximately 2.1 kcal/mol to helix orientation preference.}, author = {Mcclain, Diana L. and Binfet, Joseph P. and Oakley, Martha G.}, citeulike-article-id = {5624688}, citeulike-linkout-0 = {http://dx.doi.org/10.1006/jmbi.2001.5044}, citeulike-linkout-1 = {http://linkinghub.elsevier.com/retrieve/pii/S0022283601950442}, day = {19}, doi = {10.1006/jmbi.2001.5044}, issn = {00222836}, journal = {Journal of Molecular Biology}, keywords = {coiled\_coil}, month = {October}, number = {2}, pages = {371--383}, posted-at = {2009-08-22 13:44:27}, priority = {2}, title = {Evaluation of the energetic contribution of interhelical coulombic interactions for coiled coil helix orientation specificity1}, url = {http://dx.doi.org/10.1006/jmbi.2001.5044}, volume = {313}, year = {2001} }

TY - JOUR ID - citeulike:5624688 L3 - citeulike-article-id:5624688 N2 - Coiled coils are formed by two or more α-helices that align in a parallel or an antiparallel relative orientation. The factors that determine a preference for a given relative helix orientation are incompletely understood. The helix orientation preference for the designed coiled coil, Acid-a1-Base-a1, was measured previously. This model system therefore provides a means for the experimental determination of the energetic contribution of a variety of interactions to helix orientation specificity. The antiparallel preference for Acid-a1-Base-a1 is imparted by a single buried polar interaction. Interhelical Coulombic interactions between residues at the e and g positions have been proposed to influence helix orientation preference. In the Acid-a1-Base-a1 heterodimer, potentially attractive Coulombic interactions are expected in both orientations. To determine the energetic consequences of Coulombic interactions for helix orientation preference, we have positioned a single charged residue in each peptide such that exclusively favorable interhelical Coulombic interactions can occur only in the parallel orientation. In contrast, two potentially repulsive interactions are expected in the antiparallel orientation. Because the buried polar interaction can occur only in the antiparallel orientation, interhelical Coulombic interactions favor the parallel orientation and the potential to form a buried polar interaction favors the antiparallel orientation. We find no clear preference for an antiparallel orientation in the resulting heterodimer, Acid-K e -Base-E g , suggesting that interhelical Coulombic interactions and a buried polar interaction are of approximately equal importance for helix orientation specificity. Stability measurements indicate that maintenance of all favorable electrostatic interactions and/or avoidance of two potentially repulsive interactions contributes approximately 2.1 kcal/mol to helix orientation preference. IS - 2 JF - Journal of Molecular Biology SN - 00222836 EP - 383 TI - Evaluation of the energetic contribution of interhelical coulombic interactions for coiled coil helix orientation specificity1 VL - 313 SP - 371 KW - coiled_coil AU - Mcclain, Diana AU - Binfet, Joseph AU - Oakley, Martha PY - 2001/10/19/ UR - http://dx.doi.org/10.1006/jmbi.2001.5044 ER -