Bbs5 functions as the docking compartment of Bbsome binding to Klc3 regulated by Bbs5-Ser²⁴⁶PKC-phosphorylation during mouse spermatogenesis

Abstract

A mitochondrial and a fibrous sheath form the midpiece of the mammalian sperm flagellum encircling most of the axoneme. It has been documented that Kinesin light chain 3 (KLC3) was involved although the formation procedure remains unclear. Yeast-two-hybrid dataset showed an interaction between Klc3 and Bardet-Biedl Syndrome 5 (BBS5) Protein, another molecular associated with cilia and flagella forming. In this study, we presumed that the most conserved IFT complex BBsome was involved in spermatogenesis via the interaction of one of its subunits, Bbs5 with Klc3. Firstly, the interaction between Klc3 and Bbs5 was confirmed with Co-IP. Secondly, we identified PKC phosphorylation sites in vitro by LC-MS/MS, Ser 19 and Ser 246 of Bbs5, examined the phosphorylation status of Bbs5 Ser 19 and Ser 246 in mouse testis. Co-IP was performed to find which PKC isoforms phosphorylate Bbs5. In addition, we tried to discuss the roles of Ser 19 and Ser 246 of Bbs5 in the Klc3-bbs5 interaction and in mouse spermatogenesis based on our early findings.