The Phragmoplast-Orienting Kinesin-12 Class Proteins Translate the Positional Information of the Preprophase Band to Establish the Cortical Division Zone inArabidopsis thaliana   

Abstract

The preprophase band (PPB) is a faithful but transient predictor of the division plane in somatic cell divisions. Throughout mitosis the PPBs positional information is preserved by factors that continuously mark the division plane at the cell cortex, the cortical division zone, by their distinct spatio-temporal localization patterns. However, the mechanism maintaining these identity factors at the plasma membrane after PPB disassembly remains obscure. The pair of kinesin-12 class proteins PHRAGMOPLAST ORIENTING KINESIN1 (POK1) and POK2 are key players in division plane maintenance. Here, we show that POK1 is continuously present at the cell cortex, providing a spatial reference for the site formerly occupied by the PPB. Fluorescence recovery after photobleaching analysis combined with microtubule destabilization revealed dynamic microtubule-dependent recruitment of POK1 to the PPB during prophase, while POK1 retention at the cortical division zone in the absence of cortical microtubules appeared static. POK function is strictly required to maintain the division plane identity factor TANGLED (TAN) after PPB disassembly, although POK1 and TAN recruitment to the PPB occur independently during prophase. Together, our data suggest that POKs represent fundamental early anchoring components of the cortical division zone, translating and preserving the positional information of the PPB by maintaining downstream identity markers.

Kinesin-12 motors cooperate to suppress microtubule catastrophes and drive the formation of parallel microtubule bundles

“…Moreover, the capacity of hKif15 to drive formation of parallel bundles could explain the reported role for Caenorhabditis elegans Kinesin-12 (KLP-18) in converting disordered microtubules that are present around meiotic chromosomes into an ordered parallel array (29,30). Intriguingly, Kinesin-12s may have more diverse roles with emerging evidence suggesting that these motors are important for shaping parallel microtubule arrays within developing neuronal axons (31) and execution of cytokinesis in angiosperms (32)(33)(34). Thus, the capacity for Kinesin-12 family members to remodel dynamic microtubule networks is likely to be crucial in multiple biological systems, and it will be interesting to investigate whether they use the same mechanism.…”

Binding of SEC11 Indicates Its Role in SNARE Recycling after Vesicle Fusion and Identifies Two Pathways for Vesicular Traffic to the Plasma Membrane

“…To test SEC11 peptide interaction with SYP121 in vivo, we transiently transformed Arabidopsis seedlings using the tricistronic vector pBiFCt-2in1-NC for ratiometric bimolecular fluorescence complementation (rBiFC) (Grefen and Blatt, 2012a;Karnik et al, 2013b;Blatt and Grefen, 2014;Lipka et al, 2014). The 2in1 rBiFC system incorporates a set of independent Gateway-compatible cassettes with coding sequences for the two halves of YFP, nYFP and cYFP, to generate fusion constructs for coexpression and testing of fluorescence complementation in the plant.…”

Arabidopsis KCBP interacts with AIR9 but stays in the cortical division zone throughout mitosis via its MyTH4-FERM domain

“…Persistence of RanGAP1 at the cortical division site beyond preprophase, however, is dependent on two kinesins, POK1 and POK2 (Müller et al, 2006) -kinesins that are implicated in the association of TAN with the predicted division site. A recent publication shows that the POK1 kinesin too is a continuous marker of the cell division plane and remains attached to the cortex from prophase to cytokinesis (Lipka et al, 2014). FASS/ TONNEAU2 itself, or at least its maize homologue DISCORDIA1, remains in the CDZ until metaphase, after which it disappears from the cortex (Wright et al, 2009).…”