Molecular characterization of rat cvHsp/HspB7 in vitro and its dynamic molecular architecture

Cardiovascular heat shock protein (cvHsp) is an abundant and selectively expressed component in cardiac tissue with putative molecular functionality. The most prominent feature of cvHsp is the characteristic α-crystallin domain, which makes it a member of the small heat shock protein (sHsp) family. In the present study, we cloned and expressed the cvHsp gene, purified cvHsp to homogeneity, and characterized its structural and molecular properties. The cvHsp mainly consisted of β-sheets and randomly coiled secondary structural elements, and in addition possessed variable tertiary structures and several solvent-exposed hydrophobic patches on its molecular surface. The purified cvHsp existed as a mixture of dimers and oligomers containing 12 monomers, and exhibited subunit exchange capacity when labeled with AIAS and LYI. In total, the cvHsp was characterized as having an oligomeric molecular architecture, and displayed various properties common to the sHsp family. The cvHsp gene may have physiologically important implications in the cardiac stress response.