Rsph9 is critical for ciliary radial spoke assembly and central pair microtubule stability

2018 ◽  
Vol 111 (2) ◽  
pp. 29-38 ◽  
Author(s):  
Lei Zhu ◽  
Hao Liu ◽  
Yawen Chen ◽  
Xiumin Yan ◽  
Xueliang Zhu
Keyword(s):  
Central Pair ◽  
Radial Spoke ◽  
Microtubule Stability

scholarly journals Distinct architecture and composition of mouse axonemal radial spoke head revealed by cryo-EM

2019 ◽  
Author(s):  
Wei Zheng ◽  
Fan Li ◽  
Zhanyu Ding ◽  
Hao Liu ◽  
Lei Zhu ◽  
...  
Keyword(s):  
Interaction Network ◽  
Core Complex ◽  
Central Pair ◽  
Radial Spoke ◽  
Ciliary Motility ◽  
Axonemal Dynein ◽  
Compact Body ◽  
Dynein Arms

AbstractThe radial spoke (RS) transmits mechanochemical signals from the central pair apparatus (CP) to axonemal dynein arms to coordinate ciliary motility. The RS head, directly contacting with CP, differs dramatically in morphology between protozoan and mammal. Here we show the murine RS head is compositionally distinct from the Chlamydomonas one. Our reconstituted murine RS head core complex consists of Rsph1, Rsph3b, Rsph4a, and Rsph9, lacking Rsph6a whose orthologue exists in the Chlamydomonas RS head. We present the unprecedented cryo-EM structure of RS head core complex at 4.5-Å resolution and identified the subunit location and their interaction network. In this complex, Rsph3b, Rsph4a, and Rsph9 forms a compact body with Rsph4a serving possibly as an assembly scaffold and Rsph3b in a location that might link the head with stalk. Interestingly, two Rsph1 subunits constitute the two stretching-arms possibly for optimized RS-CP interaction. We also propose a sawtooth model for the RS-CP interaction. Our study suggests that the RS head experiences profound remodeling to probably comply with both structural and functional alterations of the axoneme during evolution.

scholarly journals Distinct architecture and composition of mouse axonemal radial spoke head revealed by cryo-EM

2021 ◽  
Vol 118 (4) ◽  
pp. e2021180118
Author(s):  
Wei Zheng ◽  
Fan Li ◽  
Zhanyu Ding ◽  
Hao Liu ◽  
Lei Zhu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Brake Pad ◽  
Core Complex ◽  
Central Pair ◽  
Radial Spoke ◽  
The Core ◽  
Cryo Electron Microscopy ◽  
Compact Body ◽  
Β Sheets ◽  
Cilia And Flagella

The radial spoke (RS) heads of motile cilia and flagella contact projections of the central pair (CP) apparatus to coordinate motility, but the morphology is distinct for protozoa and metazoa. Here we show the murine RS head is compositionally distinct from that ofChlamydomonas. Our reconstituted murine RS head core complex consists of Rsph1, Rsph3b, Rsph4a, and Rsph9, lacking Rsph6a and Rsph10b, whose orthologs exist in the protozoan RS head. We resolve its cryo-electron microscopy (cryo-EM) structure at 3.2-Å resolution. Our atomic model further reveals a twofold symmetric brake pad-shaped structure, in which Rsph4a and Rsph9 form a compact body extended laterally with two long arms of twisted Rsph1 β-sheets and potentially connected dorsally via Rsph3b to the RS stalk. Furthermore, our modeling suggests that the core complex contacts the periodic CP projections either rigidly through its tooth-shaped Rsph4a regions or elastically through both arms for optimized RS–CP interactions and mechanosignal transduction.

scholarly journals Chlamydomonas reinhardtii hydin is a central pair protein required for flagellar motility

2007 ◽  
Vol 176 (4) ◽  
pp. 473-482 ◽  
Author(s):  
Karl-Ferdinand Lechtreck ◽  
George B. Witman
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Flagellar Motility ◽  
Central Pair ◽  
Radial Spoke ◽  
Knock Down ◽  
Flagellar Protein ◽  
Strong Candidate ◽  
Biochemical Analyses

Mutations in Hydin cause hydrocephalus in mice, and HYDIN is a strong candidate for causing hydrocephalus in humans. The gene is conserved in ciliated species, including Chlamydomonas reinhardtii. An antibody raised against C. reinhardtii hydin was specific for an ∼540-kD flagellar protein that is missing from axonemes of strains that lack the central pair (CP). The antibody specifically decorated the C2 microtubule of the CP apparatus. An 80% knock down of hydin resulted in short flagella lacking the C2b projection of the C2 microtubule; the flagella were arrested at the switch points between the effective and recovery strokes. Biochemical analyses revealed that hydin interacts with the CP proteins CPC1 and kinesin-like protein 1 (KLP1). In conclusion, C. reinhardtii hydin is a CP protein required for flagellar motility and probably involved in the CP–radial spoke control pathway that regulates dynein arm activity. Hydrocephalus caused by mutations in hydin likely involves the malfunctioning of cilia because of a defect in the CP.

scholarly journals Characterization of a Chlamydomonas Insertional Mutant that Disrupts Flagellar Central Pair Microtubule-associated Structures

1999 ◽  
Vol 144 (2) ◽  
pp. 293-304 ◽  
Author(s):  
David R. Mitchell ◽  
Winfield S. Sale
Keyword(s):  
Beat Frequency ◽  
Live Cells ◽  
Flagellar Motility ◽  
Wild Type ◽  
Electron Microscopic ◽  
Central Pair ◽  
Radial Spoke ◽  
Flagellar Beat ◽  
Sds Page

Two alleles at a new locus, central pair–associated complex 1 (CPC1), were selected in a screen for Chlamydomonas flagellar motility mutations. These mutations disrupt structures associated with central pair microtubules and reduce flagellar beat frequency, but do not prevent changes in flagellar activity associated with either photophobic responses or phototactic accumulation of live cells. Comparison of cpc1 and pf6 axonemes shows that cpc1 affects a row of projections along C1 microtubules distinct from those missing in pf6, and a row of thin fibers that form an arc between the two central pair microtubules. Electron microscopic images of the central pair in axonemes from radial spoke–defective strains reveal previously undescribed central pair structures, including projections extending laterally toward radial spoke heads, and a diagonal link between the C2 microtubule and the cpc1 projection. By SDS-PAGE, cpc1 axonemes show reductions of 350-, 265-, and 79-kD proteins. When extracted from wild-type axonemes, these three proteins cosediment on sucrose gradients with three other central pair proteins (135, 125, and 56 kD) in a 16S complex. Characterization of cpc1 provides new insights into the structure and biochemistry of the central pair apparatus, and into its function as a regulator of dynein-based motility.

scholarly journals The roles of a flagellar HSP40 ensuring rhythmic beating

2019 ◽  
Vol 30 (2) ◽  
pp. 228-241 ◽  
Author(s):  
Xiaoyan Zhu ◽  
Emiliya Poghosyan ◽  
Lenka Rezabkova ◽  
Bridget Mehall ◽  
Hitoshi Sakakibara ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Biochemical Analysis ◽  
De Novo ◽  
Electron Tomography ◽  
Donor Cell ◽  
Central Pair ◽  
Radial Spoke ◽  
Cryo Electron Tomography ◽  
Rigid Conformation ◽  
Mechanical Feedback

HSP40s are regarded as cochaperones, perpetually shuttling client polypeptides to HSP70s for refolding. However, many HSP40s that are central for disparate processes diverge from this paradigm. To elucidate the noncanonical mechanisms, we investigated HSP40 in the radial spoke (RS) complex in flagella. Disruption of the gene by the MRC1 transposon in Chlamydomonas resulted in jerky flagella. Traditional electron microscopy, cryo-electron tomography, and sub-tomogram analysis revealed RSs of various altered morphologies that, unexpectedly, differed between the two RS species. This indicates that HSP40 locks the RS into a functionally rigid conformation, facilitating its interactions with the adjacent central pair apparatus for transducing locally varied mechanical feedback, which permits rhythmic beating. Missing HSP40, like missing RSs, could be restored in a tip-to-base direction when HSP40 mutants fused with a HSP40 donor cell. However, without concomitant de novo RS assembly, the repair was exceedingly slow, suggesting HSP40/RS-coupled intraflagellar trafficking and assembly. Biochemical analysis and modeling uncovered spoke HSP40’s cochaperone traits. On the basis of our data, we propose that HSP40 accompanies its client RS precursor when traveling to the flagellar tip. Upon arrival, both refold in concert to assemble into the mature configuration. HSP40’s roles in chaperoning and structural maintenance shed new light on its versatility and flagellar biology.

scholarly journals Bend propagation drives central pair rotation in Chlamydomonas reinhardtii flagella

2004 ◽  
Vol 166 (5) ◽  
pp. 709-715 ◽  
Author(s):  
David R. Mitchell ◽  
Masako Nakatsugawa
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Wild Type ◽  
Central Pair ◽  
Radial Spoke ◽  
Passive Response ◽  
Mutant Strains ◽  
Radial Spokes ◽  
Presence And Absence ◽  
Cilia And Flagella ◽  
Pair Interactions

Regulation of motile 9+2 cilia and flagella depends on interactions between radial spokes and a central pair apparatus. Although the central pair rotates during bend propagation in flagella of many organisms and rotation correlates with a twisted central pair structure, propulsive forces for central pair rotation and twist are unknown. Here we compared central pair conformation in straight, quiescent flagella to that in actively beating flagella using wild-type Chlamydomonas reinhardtii and mutants that lack radial spoke heads. Twists occur in quiescent flagella in both the presence and absence of spoke heads, indicating that spoke–central pair interactions are not needed to generate torque for twisting. Central pair orientation in propagating bends was also similar in wild type and spoke head mutant strains, thus orientation is a passive response to bend formation. These results indicate that bend propagation drives central pair rotation and suggest that dynein regulation by central pair–radial spoke interactions involves passive central pair reorientation to changes in bend plane.

scholarly journals Targeted NGS gene panel identifies mutations in RSPH1 causing primary ciliary dyskinesia and a common mechanism for ciliary central pair agenesis due to radial spoke defects

2014 ◽  
Vol 23 (13) ◽  
pp. 3362-3374 ◽  
Author(s):  
Alexandros Onoufriadis ◽  
Amelia Shoemark ◽  
Miriam Schmidts ◽  
Mitali Patel ◽  
Gina Jimenez ◽  
...  
Keyword(s):  
Primary Ciliary Dyskinesia ◽  
Gene Panel ◽  
Common Mechanism ◽  
Central Pair ◽  
Radial Spoke ◽  
Targeted Ngs ◽  
Ciliary Dyskinesia
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