The degradation of kinesin-like calmodulin binding protein of D. salina (DsKCBP) is mediated by the ubiquitin–proteasome system

• Published in: Molecular biology reports 2013-04, Vol.40 (4), p.3113-3121
• Main Authors: Shi, Ke, Li, Jie, Han, Kang, Jiang, Haili, Xue, Lexun
• Format: Article
• Language: English
• Subjects: Animal Anatomy; Animal Biochemistry; Binding Sites; Biomedical and Life Sciences; Calmodulin-Binding Proteins - chemistry; Calmodulin-Binding Proteins - genetics; Calmodulin-Binding Proteins - metabolism; Dunaliella salina; Flagella - metabolism; Histology; Kinesin - chemistry; Kinesin - metabolism; Life Sciences; Microtubules - genetics; Microtubules - metabolism; Morphology; Proteasome Endopeptidase Complex - genetics; Proteasome Endopeptidase Complex - metabolism; Protein Binding; Protein Structure, Tertiary; Proteolysis; Salina; Sequence Homology, Amino Acid; Ubiquitin - metabolism; Volvocida - genetics; Volvocida - metabolism
• ISSN: 0301-4851; 1573-4978
• DOI: 10.1007/s11033-012-2385-2

Kinesin-like calmodulin binding protein (KCBP) is a member of kinesin-14 subfamily with unconventional domains distinct from other kinesins. This unique kinesin has the myosin tail homology 4 domain (MyTH4) and band4.1, ezrin, radixin and moesin domain (FERM) at the N-terminal which interact with several cytoskeleton proteins. Although KCBP is implicated in several microtubule-related cellular processes, studies on the KCBP of Dunaliella salina (DsKCBP) have not been reported. In this study, the roles of DsKCBP in flagella and cytoskeleton were investigated and the results showed that DsKCBP was present in flagella and upregulated during flagellar assembly indicting that it may be a flagellar kinesin and plays a role in flagellar assembly. A MyTH4-FERM domain of the DsKCBP was identified as a microtubule and actin interacting site. The interaction of DsKCBP with both microtubules and actin microfilaments suggests that this kinesin may be employed to coordinate these two cytoskeleton elements in algal cells. To gain more insights into the cellular function of the kinesin, DsKCBP-interacting proteins were examined using yeast two-hybrid screen. A 26S proteasome subunit Rpn8 was identified as a novel interacting partner of DsKCBP and the MyTH4-FERM domain was necessary for the interaction of DsKCBP with Rpn8. Furthermore, the DsKCBP was polyubiquitinated and up-regulated by proteasome inhibitor and degraded by ubiquitin–proteasome system indicating that proteasome is related to kinesin degradation.