Calmodulin is Required for Paraflagellar Rod Assembly and Flagellum-Cell Body Attachment in Trypanosomes

Ginger, Michael L.; Collingridge, Peter; Brown, Rob; Sproat, Rhona; Shaw, Michael K.; Gull, Keith

doi:10.1016/j.protis.2013.05.002

Cited by 37 publications

(49 citation statements)

References 54 publications

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“…However, calcium-calmodulin binding might be involved in sorting the motor to different target membranes. Consistent with this, it was recently reported that calmodulin is required for paraflagellar rod assembly and flagellum-cell-body attachment in trypanosomes (42).…”

Section: Discussionsupporting

confidence: 72%

“…The following observations suggest that expression levels of different Leishmania-specific CamLs and cytosolic calcium might regulate myosin function in this system: (i) two very different Leishmania CamL proteins bound to a single-peptide sequence in the strongest dimerization domain on myosin XXI, and these proteins differ in K d and calcium sensitivity; (ii) in vitro (human) calmodulin binding affected myosin-XXI dimerization, lipid binding, and motility; (iii) cytosolic calcium levels in the parasite are reported to be kept very low and tightly regulated (43); (iv) the expression levels of CamLs in the parasite are still largely unknown. However, downregulation of cytosolic calmodulin affects the parasite's paraflagellar rod assembly (42), which is where myosin XXI has been localized (3,7). Intriguingly, we have now identified eight other calmodulin-like proteins in the fully sequenced genome of the Leishmania parasite.…”

Section: Discussionmentioning

confidence: 91%

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Calmodulin regulates dimerization, motility, and lipid binding of Leishmania myosin XXI

Batters

Ellrich

Helbig

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Myosin XXI is the only myosin expressed in Leishmania parasites. Although it is assumed that it performs a variety of motile functions, the motor's oligomerization states, cargo-binding, and motility are unknown. Here we show that binding of a single calmodulin causes the motor to adopt a monomeric state and to move actin filaments. In the absence of calmodulin, nonmotile dimers that cross-linked actin filaments were formed. Unexpectedly, structural analysis revealed that the dimerization domains include the calmodulin-binding neck region, essential for the generation of force and movement in myosins. Furthermore, monomeric myosin XXI bound to mixed liposomes, whereas the dimers did not. Lipid-binding sections overlapped with the dimerization domains, but also included a phox-homology domain in the converter region. We propose a mechanism of myosin regulation where dimerization, motility, and lipid binding are regulated by calmodulin. Although myosin-XXI dimers might act as nonmotile actin cross-linkers, the calmodulin-binding monomers might transport lipid cargo in the parasite.unconventional myosin | motor properties

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 91%

Calmodulin regulates dimerization, motility, and lipid binding of Leishmania myosin XXI

Batters

Ellrich

Helbig

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…This could be explained if FLA1BP was anchored to a skeletal element associated to the flagellum and if FLAM3 was either a component of, or a linker to this element. The PFR has been proposed to contribute to flagellum attachment (Demonchy et al, 2009;Ginger et al, 2013). However, perturbation of PFR assembly upon ablation of PFR2 (albeit without visible alteration of the FAZ connectors) does not interfere with the regular distribution of FAZ1, FLA1, FLA1BP and FLAM3 (Fig.…”

Section: Discussionmentioning

confidence: 96%

Flagellar adhesion inTrypanosoma bruceirelies on interactions between different skeletal structures present in the flagellum and in the cell body

Rotureau

Blisnick

Subota

et al. 2013

Journal of Cell Science

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The Trypanosoma brucei flagellum is an essential organelle anchored along the surface of the cell body through a specialized structure called the flagellum attachment zone (FAZ). Adhesion relies on the interaction of the extracellular portion of two transmembrane proteins, FLA1 and FLA1BP. Here, we identify FLAM3 as a novel large protein associated with the flagellum skeleton whose ablation inhibits flagellum attachment. FLAM3 does not contain transmembrane domains and its flagellar localization matches closely, but not exactly, that of the paraflagellar rod, an extraaxonemal structure present in the flagellum. Knockdown of FLA1 or FLAM3 triggers similar defects in motility and morphogenesis, characterized by the assembly of a drastically reduced FAZ filament. FLAM3 remains associated with the flagellum skeleton even in the absence of adhesion or a normal paraflagellar rod. However, the protein is dispersed in the cytoplasm when flagellum formation is inhibited. By contrast, FLA1 remains tightly associated with the FAZ filament even in the absence of a flagellum. In these conditions, the extracellular domain of FLA1 points to the cell surface. FLAM3 is essential for proper distribution of FLA1BP, which is restricted to the most proximal portion of the flagellum upon knockdown of FLAM3. We propose that FLAM3 is a key component of the FAZ connectors that link the axoneme to the adhesion zone, hence it acts in an equivalent manner to the FAZ filament complex, but on the side of the flagellum.

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“…3D,E) and immunofluorescence using 20H5 (data not shown) revealed loss of normal 'bi-lobe' architecture, indicating TbTBCCD1 plays an important role in organising the formation of this structure. A flagellum detachment phenotype in some RNAi-induced cells suggested either (1) synthesis and vesicular trafficking via the Golgi of surface-associated glycoconjugates was potentially affected by loss of bi-lobe organisation -stable attachment of the flagellum to the cell body is dependent upon members of the trypanosomatid-specific FLA1 glycoprotein family (discussed further in Sun et al, 2013;Ginger et al, 2013) -or (2) the flagellar neck region, as well as bi-lobe organisation, was disrupted following RNAi induction, such that flagellum-cell-body attachment at the flagellar pocket exit point could become compromised.…”

Section: Morphogenetic Failures In Tbtbccd1 Rnai Lines Loss Of 'Bi-lomentioning

confidence: 99%

Tubulin-binding cofactor C domain-containing protein TBCCD1 orchestrates cytoskeletal filament formation

André

Harrison

Towers

et al. 2013

Journal of Cell Science

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SummaryTBCCD1 is an enigmatic member of the tubulin-binding cofactor C (TBCC) family of proteins required for mother-daughter centriole linkage in the green alga Chlamydomonas reinhardtii and nucleus-centrosome-Golgi linkage in mammalian cells. Loss of these linkages has severe morphogenetic consequences, but the mechanism(s) through which TBCCD1 contributes to cell organisation is unknown. In the African sleeping sickness parasite Trypanosoma brucei a microtubule-dominant cytoskeleton dictates cell shape, influencing strongly the positioning and inheritance patterns of key intracellular organelles. Here, we show the trypanosome orthologue of TBCCD1 is found at multiple locations: centrioles, the centriole-associated Golgi 'bi-lobe', and the anterior end of the cell body. Loss of Trypanosoma brucei TBCCD1 results in disorganisation of the structurally complex bi-lobe architecture and loss of centriole linkage to the single unit-copy mitochondrial genome (or kinetoplast) of the parasite. We therefore identify TBCCD1 as an essential protein associated with at least two filament-based structures in the trypanosome cytoskeleton. The last common ancestor of trypanosomes, animals and green algae was arguably the last common ancestor of all eukaryotes. On the basis of our observations, and interpretation of published data, we argue for an unexpected co-option of the TBCC domain for an essential non-tubulin-related function at an early point during evolution of the eukaryotic cytoskeleton.

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Calmodulin is Required for Paraflagellar Rod Assembly and Flagellum-Cell Body Attachment in Trypanosomes

Cited by 37 publications

References 54 publications

Calmodulin regulates dimerization, motility, and lipid binding of Leishmania myosin XXI

Calmodulin regulates dimerization, motility, and lipid binding of Leishmania myosin XXI

Flagellar adhesion inTrypanosoma bruceirelies on interactions between different skeletal structures present in the flagellum and in the cell body

Tubulin-binding cofactor C domain-containing protein TBCCD1 orchestrates cytoskeletal filament formation

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