TY - JOUR T1 - Critical domains of moss KCBP kinesin for cargo transport JF - bioRxiv DO - 10.1101/629733 SP - 629733 AU - Mari W. Yoshida AU - MoƩ Yamada AU - Gohta Goshima Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/05/07/629733.abstract N2 - KCBP is a microtubule (MT) minus-end-directed kinesin widely conserved in plants. It was shown in Arabidopsis that KCBP controls trichome cell shape by orchestrating MT and actin cytoskeletons using its tail and motor domains. In contrast, the KCBP knockout (KO) line in the moss Physcomitrella patens showed a defect in nuclear and organelle positioning in apical stem cells. Moss KCBP is postulated to transport the nucleus and chloroplast via direct binding to their membranes, since it binds to and transports liposomes composed of phospholipids in vitro. However, domains required for cargo transport in vivo have not been mapped. Here, we performed a structure-function analysis of moss KCBP. We found that the FERM domain in the tail region, which is known to bind to lipids as well as other proteins, is essential for both nuclear and chloroplast positioning, whereas the proximal MyTH4 domain plays an important but non-essential role. Interestingly, KCBP accumulates on the chromosomes, in particular at the centromeric region, after anaphase, which precedes the completion of nuclear envelope formation. Chromosomal enrichment of KCBP is correlated with its ability to translocate the chromosomes at this specific stage of the cell cycle. These results suggest that KCBP binds to non-membranous naked chromosomes via an unidentified protein(s) for their transport. Finally, the liverwort orthologue rescued the chromosome/chloroplast mis-positioning of the moss KCBP KO line, suggesting that the cargo transport function of KCBP is conserved in plants. ER -