Conformational discrimination of three human centrins

Abstract

Centrin belongs to the calcium-binding super-family, and is essential for the microtubule-organizing center (MTOC). With different locations and functions in the cell, three human centrin proteins have been identified. To obtain their structural basis, using 2-p-toluidinylnaphthalene-6-sulfonate (TNS) as a fluorescent probe, we investigated their conformational discrimination. The results suggest that the three human centrins contain large hydrophobic cavities, and the hydrophobic cavity of human centrin 1 (HsCen1) was the most pronounced. In addition, Tb³⁺ may induce centrin conformational changes and hydrophobic surface exposure. In 100 mM N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid (Hepes, pH 7.4) at different temperatures, thermodynamic data of centrin binding with TNS were measured. Based on Förster non-radiative energy transfer theory, the distances of TNS binding with human centrins HsCen1, HsCen2, and HsCen3 were measured. These results may provide some insight into structural information regarding why the three human centrins exhibit various biological functions.