scholarly journals The Complex of Outer-arm Dynein Light Chain-1 and the Microtubule-binding Domain of the Heavy Chain Shows How Axonemal Dynein Tunes Ciliary Beating

2021 ◽  
Vol 61 (1) ◽  
pp. 020-022
Author(s):  
Toshiki YAGI ◽  
Akiyuki TODA ◽  
Muneyoshi ICHIKAWA ◽  
Genji KURISU
Keyword(s):  
Heavy Chain ◽  
Light Chain ◽  
Binding Domain ◽  
Dynein Light Chain ◽  
Microtubule Binding ◽  
Ciliary Beating ◽  
Microtubule Binding Domain ◽  
Axonemal Dynein

scholarly journals Axonemal dynein light chain-1 locates at the microtubule-binding domain of the γ heavy chain

2015 ◽  
Vol 26 (23) ◽  
pp. 4236-4247 ◽  
Author(s):  
Muneyoshi Ichikawa ◽  
Kei Saito ◽  
Haru-aki Yanagisawa ◽  
Toshiki Yagi ◽  
Ritsu Kamiya ◽  
...  
Keyword(s):  
Light Chain ◽  
Regulatory Mechanism ◽  
Binding Domain ◽  
Particle Analysis ◽  
Dynein Light Chain ◽  
Microtubule Binding ◽  
Heavy Chains ◽  
Microtubule Binding Domain ◽  
Axonemal Dynein ◽  
Force Generator

The outer arm dynein (OAD) complex is the main propulsive force generator for ciliary/flagellar beating. In Chlamydomonas and Tetrahymena, the OAD complex comprises three heavy chains (α, β, and γ HCs) and >10 smaller subunits. Dynein light chain-1 (LC1) is an essential component of OAD. It is known to associate with the Chlamydomonas γ head domain, but its precise localization within the γ head and regulatory mechanism of the OAD complex remain unclear. Here Ni-NTA-nanogold labeling electron microscopy localized LC1 to the stalk tip of the γ head. Single-particle analysis detected an additional structure, most likely corresponding to LC1, near the microtubule-binding domain (MTBD), located at the stalk tip. Pull-down assays confirmed that LC1 bound specifically to the γ MTBD region. Together with observations that LC1 decreased the affinity of the γ MTBD for microtubules, we present a new model in which LC1 regulates OAD activity by modulating γ MTBD's affinity for the doublet microtubule.

scholarly journals The complex of outer-arm dynein light chain-1 and the microtubule-binding domain of the γ heavy chain shows how axonemal dynein tunes ciliary beating

2020 ◽  
Vol 295 (12) ◽  
pp. 3982-3989 ◽  
Author(s):  
Akiyuki Toda ◽  
Yosuke Nishikawa ◽  
Hideaki Tanaka ◽  
Toshiki Yagi ◽  
Genji Kurisu
Keyword(s):  
Binding Affinity ◽  
Light Chain ◽  
Mutational Analysis ◽  
Molecular Model ◽  
Binding Domain ◽  
Structural Basis ◽  
Dynein Light Chain ◽  
Microtubule Binding ◽  
Microtubule Binding Domain ◽  
Axonemal Dynein

Axonemal dynein is a microtubule-based molecular motor that drives ciliary/flagellar beating in eukaryotes. In axonemal dynein, the outer-arm dynein (OAD) complex, which comprises three heavy chains (α, β, and γ), produces the main driving force for ciliary/flagellar motility. It has recently been shown that axonemal dynein light chain-1 (LC1) binds to the microtubule-binding domain (MTBD) of OADγ, leading to a decrease in its microtubule-binding affinity. However, it remains unclear how LC1 interacts with the MTBD and controls the microtubule-binding affinity of OADγ. Here, we have used X-ray crystallography and pulldown assays to examine the interaction between LC1 and the MTBD, identifying two important sites of interaction in the MTBD. Solving the LC1-MTBD complex from Chlamydomonas reinhardtii at 1.7 Å resolution, we observed that one site is located in the H5 helix and that the other is located in the flap region that is unique to some axonemal dynein MTBDs. Mutational analysis of key residues in these sites indicated that the H5 helix is the main LC1-binding site. We modeled the ternary structure of the LC1-MTBD complex bound to microtubules based on the known dynein-microtubule complex. This enabled us to propose a structural basis for both formations of the ternary LC1-MTBD-microtubule complex and LC1-mediated tuning of MTBD binding to the microtubule, suggesting a molecular model for how axonemal dynein senses the curvature of the axoneme and tunes ciliary/flagellar beating.

scholarly journals Backbone and partial side chain assignment of the microtubule binding domain of the MAP1B light chain

2013 ◽  
Vol 8 (1) ◽  
pp. 123-127 ◽  
Author(s):  
Zsuzsanna Orbán-Németh ◽  
Morkos A. Henen ◽  
Leonhard Geist ◽  
Szymon Żerko ◽  
Saurabh Saxena ◽  
...  
Keyword(s):  
Light Chain ◽  
Binding Domain ◽  
Side Chain ◽  
Microtubule Binding ◽  
Microtubule Binding Domain

scholarly journals Light chain 2 is a Tctex-type related axonemal dynein light chain that regulates directional ciliary motility in Trypanosoma brucei

2021 ◽  
Author(s):  
Subash Godar ◽  
James Oristian ◽  
Valerie Hinsch ◽  
Katherine Wentworth ◽  
Ethan Lopez ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Trypanosoma Brucei ◽  
Light Chain ◽  
Light Chains ◽  
Dynein Light Chain ◽  
Ciliary Beating ◽  
Ciliary Motility ◽  
Dynein Motor ◽  
Axonemal Dynein ◽  
Bending Wave

AbstractFlagellar motility is essential for the cell morphology, viability, and virulence of pathogenic kinetoplastids, including trypanosomes. Trypanosoma brucei flagella exhibit a bending wave that propagates from the flagellum’s tip to its base, rather than base-to-tip as in other eukaryotes. Thousands of dynein motor proteins coordinate their activity to drive ciliary bending wave propagation. Dynein- associated light and intermediate chains regulate the biophysical mechanisms of axonemal dynein. Tctex- type outer arm dynein light chain 2 (LC2) regulates flagellar bending wave propagation direction, amplitude, and frequency in Chlamydomonas reinhardtii. However, the role of Tctex-type light chains in regulating T. brucei motility is unknown. Here, we used a combination of bioinformatics, in-situ molecular tagging, and immunofluorescence microscopy to identify a Tctex-type light chain in the procyclic form of T. brucei (TbLC2). We knocked down TbLC2 expression using RNAi, rescued the knockdown with eGFP- tagged TbLC2, and quantified TbLC2’s effects on trypanosome cell biology and biophysics. We found that TbLC2 knockdown resulted in kinetoplast mislocalization and the formation of multiple cell clusters in cell culture. We also found that TbLC2 knockdown reduced the directional persistence of trypanosome cell swimming, induced an asymmetric ciliary bending waveform, modulated the bias between the base-to- tip and tip-to-base beating modes, and increased the beating frequency. Together, our findings are consistent with a model of TbLC2 as a down-regulator of axonemal dynein activity that stabilizes the forward tip-to-base beating ciliary waveform characteristic of trypanosome cells. Our work sheds light on axonemal dynein regulation mechanisms that contribute to pathogenic kinetoplastids’ unique tip-to-base ciliary beating nature and how those mechanisms underlie dynein-driven ciliary motility more generally.Author SummaryKinetoplastea is a class of ciliated protists that include parasitic trypanosomes, which cause severe disease in people and livestock in tropical regions across the globe. All trypanosomes, including Trypanosoma brucei, require a cilium to provide propulsive force for directional swimming motility, host immune evasion, and various aspects of their cell cycle. Thus, a functional cilium is essential for the virulence of the parasite.Trypanosome cilia exhibit a unique tip-to-base beating mechanism, different from the base-to-tip beating of most other eukaryotic cilia. Multiple ciliary proteins are involved in the complex biophysical and biochemical mechanisms that underly the trypanosome ciliary beating. These include dynein motor proteins that power the beat, dynein-related light chains that regulate the beat, and many other proteins in the nexin-dynein regulatory complex, in the radial spokes, and associated with the central pair of microtubules, for example.Here, we identify a Tctex-type dynein light chain in T. brucei that we named TbLC2 because it has sequence homology, structural similarity, and ciliary localization like LC2 homologs in other organisms. We demonstrate that TbLC2 has critical dynein regulatory functions, with implications on the unique aspects of trypanosome ciliary beating and cellular swimming motility. Our study represents an additional step toward understanding the functions of the trypanosome ciliary proteome, which could provide novel therapeutic targets against the unique aspects of trypanosome ciliary motility.

scholarly journals Structure and Functional Role of Dynein's Microtubule-Binding Domain

Science ◽  
2008 ◽  
Vol 322 (5908) ◽  
pp. 1691-1695 ◽  
Author(s):  
A. P. Carter ◽  
J. E. Garbarino ◽  
E. M. Wilson-Kubalek ◽  
W. E. Shipley ◽  
C. Cho ◽  
...  
Keyword(s):  
Functional Role ◽  
Binding Domain ◽  
Microtubule Binding ◽  
Microtubule Binding Domain
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