Regulation of centrin self-assembly investigated by fluorescence resonance light scattering

Abstract

Centrin self-assembly is primarily involved in fiber contraction, which is associated with the cell division cycle and ciliogenesis. During centriole separation, centrin reversible phosphorylation plays a key role. There is a question as to how centrin phosphorylation cooperatively co-exists with self-assembly during cell mitosis. Our results suggested that centrin from Euplotes octocarinatus (EoCen) in the self-assembly state can also be phosphorylated by protein kinase A (PKA). Dimers, trimers or tetramers of EoCen have nearly equal abilities of PKA phosphorylating Ser166. In turn, the phosphorylation reaction can change metal ion-induced self-assembly of EoCen. The self-assembly amount and velocity of phosphorylated EoCen were evidently reduced. The self-assembly mode can be reversed by the regulating factor KCl, but not by NaCl or LiCl. At high concentrations of KCl, the degree of EoCen self-assembly was higher than that of phosphorylated EoCen (EoCenp). There were no differences at low concentrations of KCl. Site III on EoCen may be responsible for controlling the balance between phosphorylation and self-assembly. Such results can provide valuable insights for understanding the molecular basis for centrin functions in resting or active cell mitosis.