Structural basis for misregulation of kinesin KIF21A autoinhibition by CFEOM1 disease mutations

Abstract

Tight regulation of kinesin activity is crucial and malfunction is linked to neurological diseases. Point mutations in the KIF21A gene cause congenital fibrosis of the extraocular muscles type 1 (CFEOM1) by disrupting the autoinhibitory interaction between the motor domain and a regulatory region in the stalk. However, the molecular mechanism underlying the misregulation of KIF21A activity in CFEOM1 is not understood. Here, we show that the KIF21A regulatory domain containing all disease-associated substitutions in the stalk forms an intramolecular antiparallel coiled coil that inhibits the kinesin. CFEOM1 mutations lead to KIF21A hyperactivation by affecting either the structural integrity of the antiparallel coiled coil or the autoinhibitory binding interface, thereby reducing its affinity for the motor domain. Interaction of the KIF21A regulatory domain with the KIF21B motor domain and sequence similarities to KIF7 and KIF27 strongly suggest a conservation of this regulatory mechanism in other kinesin-4 family members.

Kinesin-4 KIF21B is a potent microtubule pausing factor

“…To assess the oligomerization state of KIF21B rCC, we performed sedimentation velocity experiments (Figure 6—figure supplement 4B), which revealed a molecular weight of 11 kDa for the polypeptide chain fragment (calculated molecular weight of KIF21B rCC: 9.5 kDa). These biophysical results are consistent with KIF21B rCC forming an intramolecular antiparallel coiled coil in solution, very similar to the one we described for KIF21A (Bianchi et al, 2016). …”

“…The potent effect of KIF21B on MT plus-end polymerization is due to the presence of two MT-binding regions in its tail, which help to prevent kinesin dissociation from the tip of the growing MT. We also found that the region responsible for autoinhibition in KIF21A (Bianchi et al, 2016) is conserved in KIF21B. However, instead of blocking the motor, this element reduced motor detachment from growing MT plus ends and thus contributed to MT pause induction.…”

“…Recently, we have characterized this interaction in detail and showed that it is mediated by a regulatory region that forms an intramolecular antiparallel coiled coil (Bianchi et al, 2016). This sequence region, including the CFEOM1-associated residues, is well conserved in KIF21B (rCC, amino acids 931–1010) (Figure 6—figure supplement 3), suggesting that it might have a similar autoinhibitory function.…”

“…There are also indications that in addition to controlling MT dynamics, KIF21A plays a role in membrane transport (Lee et al, 2012). All CFEOM1-associated mutations in KIF21A localize either to the motor domain or to a predicted short coiled-coil domain in the stalk region of the molecule, and each of them prevents the autoinhibitory interaction between these two elements (Bianchi et al, 2016; Cheng et al, 2014; van der Vaart et al, 2013). The dominant character of the CFEOM1 syndrome is thus connected to the increased activity of the mutant KIF21A kinesin caused by the loss of autoinhibition (Cheng et al, 2014; van der Vaart et al, 2013).…”

Asian Zika virus isolate significantly changes the transcriptional profile and alternative RNA splicing events in a neuroblastoma cell line

“…These genes have interesting functionality. For example, HNRNPDL and RBM39 function in transcription regulation [59,60], HNRNPDL and SRSF2 regulate alternative splicing [59,61], MPRIP is involved in stress granule formation [62], CHID1 has a role in pathogen sensing [63], and KIF21A has been implicated in neurological diseases [64]. Consistent with the selection criterion, RT-PCR validation of AS events showed significant missplicing in ZIKV PR -infected cells with the greatest difference in PSI values between Mock and ZIKV PR was ~28% (RBM39).…”