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Kinesin-4 KIF21B is a potent microtubule pausing factor

View Article: PubMed Central - PubMed

ABSTRACT

Microtubules are dynamic polymers that in cells can grow, shrink or pause, but the factors that promote pausing are poorly understood. Here, we show that the mammalian kinesin-4 KIF21B is a processive motor that can accumulate at microtubule plus ends and induce pausing. A few KIF21B molecules are sufficient to induce strong growth inhibition of a microtubule plus end in vitro. This property depends on non-motor microtubule-binding domains located in the stalk region and the C-terminal WD40 domain. The WD40-containing KIF21B tail displays preference for a GTP-type over a GDP-type microtubule lattice and contributes to the interaction of KIF21B with microtubule plus ends. KIF21B also contains a motor-inhibiting domain that does not fully block the interaction of the protein with microtubules, but rather enhances its pause-inducing activity by preventing KIF21B detachment from microtubule tips. Thus, KIF21B combines microtubule-binding and regulatory activities that together constitute an autonomous microtubule pausing factor.

Doi:: http://dx.doi.org/10.7554/eLife.24746.001

No MeSH data available.


Related in: MedlinePlus

In vitro reconstitution of MT growth in the presence of 20 nM mCherry-EB3, 3% Rhodamine-tubulin and 0.5 nM KIF21B-FL-GFP.KIF21B-FL-GFP is attached to one MT and walks along another one, causing MT bending. Arrow indicates position of KIF21B-FL-GFP, yellow arrowheads trace the MT that bends.DOI:http://dx.doi.org/10.7554/eLife.24746.031
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fig6s1: In vitro reconstitution of MT growth in the presence of 20 nM mCherry-EB3, 3% Rhodamine-tubulin and 0.5 nM KIF21B-FL-GFP.KIF21B-FL-GFP is attached to one MT and walks along another one, causing MT bending. Arrow indicates position of KIF21B-FL-GFP, yellow arrowheads trace the MT that bends.DOI:http://dx.doi.org/10.7554/eLife.24746.031

Mentions: Our data presented so far indicate that a few KIF21B motors can prevent both growth and shortening by ‘holding on’ to a MT plus end. Since the dimeric motor domain of KIF21B by itself does not show such an activity, this result suggests that additional MT-binding sites that can associate with the MT plus ends must be present in the KIF21B tail. In line with this conclusion, we observed that when MTs were allowed to grow long in vitro in the presence of a low (0.5 nM) KIF21B concentration, KIF21B motors could pull a MT along another MT (Figure 6—figure supplement 1). This observation suggests that KIF21B can bind to one MT and walk along another MT at the same time.


Kinesin-4 KIF21B is a potent microtubule pausing factor
In vitro reconstitution of MT growth in the presence of 20 nM mCherry-EB3, 3% Rhodamine-tubulin and 0.5 nM KIF21B-FL-GFP.KIF21B-FL-GFP is attached to one MT and walks along another one, causing MT bending. Arrow indicates position of KIF21B-FL-GFP, yellow arrowheads trace the MT that bends.DOI:http://dx.doi.org/10.7554/eLife.24746.031
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5383399&req=5

fig6s1: In vitro reconstitution of MT growth in the presence of 20 nM mCherry-EB3, 3% Rhodamine-tubulin and 0.5 nM KIF21B-FL-GFP.KIF21B-FL-GFP is attached to one MT and walks along another one, causing MT bending. Arrow indicates position of KIF21B-FL-GFP, yellow arrowheads trace the MT that bends.DOI:http://dx.doi.org/10.7554/eLife.24746.031
Mentions: Our data presented so far indicate that a few KIF21B motors can prevent both growth and shortening by ‘holding on’ to a MT plus end. Since the dimeric motor domain of KIF21B by itself does not show such an activity, this result suggests that additional MT-binding sites that can associate with the MT plus ends must be present in the KIF21B tail. In line with this conclusion, we observed that when MTs were allowed to grow long in vitro in the presence of a low (0.5 nM) KIF21B concentration, KIF21B motors could pull a MT along another MT (Figure 6—figure supplement 1). This observation suggests that KIF21B can bind to one MT and walk along another MT at the same time.

View Article: PubMed Central - PubMed

ABSTRACT

Microtubules are dynamic polymers that in cells can grow, shrink or pause, but the factors that promote pausing are poorly understood. Here, we show that the mammalian kinesin-4 KIF21B is a processive motor that can accumulate at microtubule plus ends and induce pausing. A few KIF21B molecules are sufficient to induce strong growth inhibition of a microtubule plus end in vitro. This property depends on non-motor microtubule-binding domains located in the stalk region and the C-terminal WD40 domain. The WD40-containing KIF21B tail displays preference for a GTP-type over a GDP-type microtubule lattice and contributes to the interaction of KIF21B with microtubule plus ends. KIF21B also contains a motor-inhibiting domain that does not fully block the interaction of the protein with microtubules, but rather enhances its pause-inducing activity by preventing KIF21B detachment from microtubule tips. Thus, KIF21B combines microtubule-binding and regulatory activities that together constitute an autonomous microtubule pausing factor.

Doi:: http://dx.doi.org/10.7554/eLife.24746.001

No MeSH data available.


Related in: MedlinePlus