Control of Motor Landing and Processivity by the CAP-Gly Domain in the KIF13B Tail

Abstract

Microtubules are a major component of the eukaryotic cytoskeleton that play crucial roles in diverse cellular process. Posttranslational modifications (PTMs) of tubulin dimers regulate the dynamics and organization of microtubules, as well as the interactions between microtubules and microtubule-associated proteins (MAPs). One unique PTM that occurs on microtubules is the cyclical removal and re-addition of the C-terminal tyrosine of α-tubulin. CAP-Gly (cytoskeleton-associated protein glycine-rich) domain containing proteins specifically recognize tyrosinated microtubules, a property exploited to regulate and spatially localize diverse microtubule effectors. KIF13B is a member of the long-distance transport kinesin-3 family, and the only kinesin motor that contains a conserved C-terminal CAP-Gly domain. What role the CAP-Gly domain plays in KIF13B's motility along microtubules is unknown. Here, we investigated the interaction between KIF13B's CAP-Gly domain, and the tyrosinated C-terminal tail domain of α-tubulin. We found that KIF13B's CAP-Gly domain strongly influences the initial motor-microtubule interaction, as well as the processive motility of KIF13B along microtubules. The effect of the CAP-Gly domain on kinesin-microtubule binding is specific to the nucleotide state of the motor domain, suggesting an interplay between the N-terminal motor domain and C-terminal CAP-Gly domain underlies the KIF13B-microtubule interaction. These results reveal that specialized kinesin tail domains play active roles in the initiation and continuation of motor movement.

Comparative analysis of two Caenorhabditis elegans kinesins KLP-6 and UNC-104 reveals a common and distinct activation mechanism in kinesin-3

“…This would be because CC2 is not included in their assays. Indeed, the monomer-to-dimer conversion was observed upon release of the autoinhibition in the case of the full length of KIF13B which has the CC2 domain ( Fan and McKenney, 2022 ). The CC2 domain is conserved in most of the kinesin-3 family proteins including KIF1Bα, KIF1C, KIF13A, KIF16A, and KIF16B ( Hirokawa et al, 2009 ).…”

Comparative analysis of twoCaenorhabditis eleganskinesins KLP-6 and UNC-104 reveals a common and distinct activation mechanism in kinesin-3

“…This would be because CC2 is not included in their assays. Indeed, the monomer to dimer conversion was observed upon release of the autoinhibition in the case of the full-length of KIF13B which has the CC2 domain (Fan, 2022). The CC2 domain is conserved in most of the kinesin-3 family proteins including KIF1Bα, KIF1C, KIF13A, KIF16A and KIF16B (Hirokawa et al, 2009).…”

The chromokinesin Kid (KIF22) forms a homodimer, moves processively along microtubules and transports double-strand DNA

“…As a result, this would facilitate the formation of Kid dimers on the microtubules, leading to processive motility. These properties, such as 'the equilibrium between monomers and dimers' and 'the capability to exhibit processive movement on microtubules, even when characterized as monomers through mass photometry,' have been observed in kinesin-3 motors (28,31,32).…”

“…Recently, we and others have analyzed properties of full-length kinesins (26)(27)(28)(29). Notably, these studied have found that monomeric kinesins, including KIF1A, UNC-104 and KIF13B are converted to a dimer when activated (28,(30)(31)(32). For instance, in the autoinhibited and inactive state, KIF1A and UNC-104 are monomeric (30,32).…”