Landmark contributions of Chlamydomonas to understanding cilia

Sale, Winfield S.; Dutcher, Susan K.

doi:10.1016/b978-0-12-822508-0.00014-9

Cited by 4 publications

(4 citation statements)

References 458 publications

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“…7). The uni1 mutant, which possess only one cilium associated with the trans BB (Sale & Dutcher, 2023), exhibited a clear reduction in the ChR1 level and a slightly enhanced light-induced degradation compared to the parental strain. Both parameters were even more affected in two different bld mutants lacking both cilia (bld2 andbld7; Fig.…”

Section: Light-induced Chr1 Degradation Is Increased In Mutants With ...mentioning

confidence: 95%

Insights into degradation and targeting of the photoreceptor channelrhodopsin-1

Kreimer,

Wolfram,

Greif

et al. 2024

Preprint

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In Chlamydomonas, the directly light-gated, plasma membrane-localized (PM) cation channels channelrhodopsins ChR1 and ChR2 are the primary photoreceptors for phototaxis. Their targeting and abundance is essential for optimal movement responses. However, our knowledge how Chlamydomonas achieves this is still at its infancy. Here we show that ChR1 internalization occurs via light-stimulated endocytosis. Prior or during endocytosis ChR1 is modified and forms high molecular mass complexes. These are the solely detectable ChR1 forms in extracellular vesicles (EVs) and their abundance therein dynamically changes upon illumination. The ChR1-containing EVs are secreted via the PM and/or the ciliary base. In line with this, ciliogenesis mutants exhibit increased ChR1 degradation rates. Further, we establish involvement of two cysteine proteases in its turnover: CEP1, a papain-type C1A member, and a calpain. ΔCEP1 knock-out strains lack light-induced ChR1 degradation, whereas ChR2 degradation was unaffected. Low light stimulates CEP1 expression, which is regulated via phototropin, a SPA1 E3 ubiquitin ligase and cAMP. Further, mutant and inhibitor analyses revealed involvement of the small GTPase ARL11 and SUMOylation in ChR1 targeting to the eyespot and cilia. Our study thus defines the degradation pathway of this central photoreceptor of Chlamydomonas and identifies novel elements involved in its homeostasis and targeting.

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Section: Light-induced Chr1 Degradation Is Increased In Mutants With ...mentioning

confidence: 95%

Insights into degradation and targeting of the photoreceptor channelrhodopsin-1

Kreimer,

Wolfram,

Greif

et al. 2024

Preprint

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“…Many mutations that disrupt the assembly of ODAs, IDAs, RSs, CP, and its projections, MIA complex, N-DRC, T/TH, and FAP57 complex have been characterized over decades of work in Chlamydomonas , Tetrahymena , and other organisms, and their motility phenotypes are very diverse, ranging from flagellar paralysis, ciliary twitching, reduced beat frequency, and/or altered ciliary waveforms with reduced amplitudes (reviewed in Sale and Dutcher, 2023 ). However, ciliary motility is extremely complex, and many organisms can adjust the pattern of their waveforms in response to internal and external stimuli.…”

Section: Introductionmentioning

confidence: 99%

“…However, ciliary motility is extremely complex, and many organisms can adjust the pattern of their waveforms in response to internal and external stimuli. For instance, Chlamydomonas can adjust the beat frequency of its cis and trans cilia to undergo both positive and negative phototaxis, or it can reverse its swimming direction in response to bright light (reviewed in Witman, 1993 ; Dutcher, 2020 ; Sale and Dutcher, 2023 ). The latter involves the conversion of an asymmetric ciliary-type waveform to a more symmetric, flagellar-type waveform.…”

Section: Introductionmentioning

confidence: 99%

The MBO2/FAP58 heterodimer stabilizes assembly of inner arm dynein b and reveals axoneme asymmetries involved in ciliary waveform

Fu,

Augspurger,

Sakizadeh

et al. 2024

MBoC

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Cilia generate three-dimensional waveforms required for cell motility and transport of fluid, mucus, and particles over the cell surface. This movement is driven by multiple dynein motors attached to nine outer doublet microtubules that form the axoneme. The outer and inner arm dyneins are organized into 96 nm repeats tandemly arrayed along the length of the doublets. Motility is regulated in part by projections from the two central pair microtubules that contact radial spokes located near the base of the inner dynein arms in each repeat. Although much is known about the structures and protein complexes within the axoneme, many questions remain about the regulatory mechanisms that allow the cilia to modify their waveforms in response to internal or external stimuli. Here we used Chlamydomonas mbo (move backwards only) mutants with altered waveforms to identify at least two conserved proteins, MBO2/CCDC146 and FAP58/CCDC147, that form part of a L-shaped structure that varies between doublet microtubules. Comparative proteomics identified additional missing proteins that are altered in other motility mutants, revealing overlapping protein defects. Cryo-electron tomography and epitope tagging revealed that the L-shaped, MBO2/FAP58 structure interconnects inner dynein arms with multiple regulatory complexes, consistent with its function in modifying the ciliary waveform. [Media: see text]

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“…Many mutations that disrupt the assembly of ODAs, IDAs, RSs, CP and its projections, MIA complex, N-DRC, T/TH, and FAP57 complex have been characterized over decades of work in Chlamydomonas, Tetrahymena, and other organisms, and their motility phenotypes are very diverse, ranging from flagellar paralysis, ciliary twitching, reduced beat frequency, and/or altered ciliary waveforms with reduced amplitudes (reviewed in Sale and Dutcher, 2023).…”

Section: Introductionmentioning

confidence: 99%

The ciliary MBO2 complex targets assembly of inner arm dynein b and reveals additional doublet microtubule asymmetries

Augspurger

Sakizadeh

et al. 2023

Preprint

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Ciliary motility requires the spatiotemporal coordination of multiple dynein motors by regulatory complexes located within the 96 nm axoneme repeat. Many organisms can alter ciliary waveforms in response to internal or external stimuli, but little is known about the specific polypeptides and structural organization of complexes that regulate waveforms. In Chlamydomonas, several mutations convert the ciliary waveform from an asymmetric, ciliary-type stroke to a symmetric, flagellar-type stroke. Some of these mutations alter subunits located at the inner junction of the doublet microtubule and others alter interactions between the dynein arms and the radial spokes. These and other axonemal substructures are interconnected by a network of poorly characterized proteins. Here we re-analyze several motility mutants (mbo, fap57, pf12/pacrg) to identify new components in this network. The mbo (move backwards only) mutants are unable to swim forwards with an asymmetric waveform. Proteomics identified more than 19 polypeptides that are missing or reduced in mbo mutants, including one inner dynein arm, IDA b. Several MBO2-associated proteins are also altered in fap57 and pf12/parcg mutants, suggesting overlapping networks. Two subunits are highly conserved, coiled coil proteins found in other species with motile cilia and others contain potential signaling domains. Cryo-electron tomography and epitope tagging revealed that the MBO2 complex is found on specific doublet microtubules and forms a large, L-shaped structure that contacts the base of IDA b that interconnects multiple dynein regulatory complexes and varies in a doublet microtubule specific fashion.

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Landmark contributions of Chlamydomonas to understanding cilia

Cited by 4 publications

References 458 publications

Insights into degradation and targeting of the photoreceptor channelrhodopsin-1

Insights into degradation and targeting of the photoreceptor channelrhodopsin-1

The MBO2/FAP58 heterodimer stabilizes assembly of inner arm dynein b and reveals axoneme asymmetries involved in ciliary waveform

The ciliary MBO2 complex targets assembly of inner arm dynein b and reveals additional doublet microtubule asymmetries

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