14-3-3 Regulates Actin Filament Formation in the Deep-Branching Eukaryote Giardia lamblia

Krtková, Jana; Xu, Jennifer; Lalle, Marco; Steele-Ogus, Melissa C.; Alas, Germain C. M.; Sept, David; Paredez, Alexander R.

doi:10.1128/msphere.00248-17

Cited by 18 publications

(18 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, Giardia TTLL3 polygylcylates C-terminal glutamate residues on 14-3-3 protein (epsilon-like) that regulates actin organization (Lalle et al, 2011(Lalle et al, , 2006Krtkova et al, 2017). Ftt18, a Tetrahymena 14-3-3 protein, has been previously reported at BBs and pcMTs (Kilburn et al, 2007).…”

Section: Glycylation Of Non-tubulin Targetsmentioning

confidence: 99%

Microtubule glycylation promotes attachment of basal bodies to the cell cortex

Junker

Soh

O’Toole

et al. 2019

Journal of Cell Science

View full text Add to dashboard Cite

Motile cilia generate directed hydrodynamic flow that is important for the motility of cells and extracellular fluids. To optimize directed hydrodynamic flow, motile cilia are organized and oriented into a polarized array. Basal bodies (BBs) nucleate and position motile cilia at the cell cortex. Cytoplasmic BB-associated microtubules are conserved structures that extend from BBs. By using the ciliate, Tetrahymena thermophila, combined with EM-tomography and light microscopy, we show that BB-appendage microtubules assemble coincidently with new BB assembly and that they are attached to the cell cortex. These BB-appendage microtubules are specifically marked by post translational modifications of tubulin, including glycylation. Mutations that prevent glycylation shorten BB-appendage microtubules and disrupt BB positioning and cortical attachment. Consistent with the attachment of BB-appendage microtubules to the cell cortex to position BBs, mutations that disrupt the cellular cortical cytoskeleton disrupt the cortical attachment and positioning of BBs. In summary, BB-appendage microtubules promote the organization of ciliary arrays through attachment to the cell cortex.

show abstract

Section: Glycylation Of Non-tubulin Targetsmentioning

confidence: 99%

Microtubule glycylation promotes attachment of basal bodies to the cell cortex

Junker

Soh

O’Toole

et al. 2019

Journal of Cell Science

View full text Add to dashboard Cite

show abstract

“…We identified Flangin, a protein with three putative WH2-like domains and a Bro1 domain all implicated in mediating interaction with actin. While in vitro assays testing direct interactions with actin are routine in model eukaryotes, it has proven challenging to produce sufficient quantities of Gl Actin for these assays (10, 12). Therefore, we cannot yet conclude whether the WH2-like and/or Bro1 domains of Flangin directly mediate actin interaction.…”

Section: Discussionmentioning

confidence: 99%

“…A previous effort at biochemically isolating ABPs from Giardia identified several proteins that associate with Gl Actin. However, these proteins likely associate with monomeric actin, based the lack of filamentous localization patterns and the biochemical conditions used to isolate these proteins (12, 13). Therefore, the previously identified proteins are unlikely to account for the full complement of ABPs in Giardia .…”

Section: Introductionmentioning

confidence: 99%

TheGiardialamellipodium-like ventrolateral flange supports attachment and rapid cytokinesis

Gcm

Taparia

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Attachment to the intestinal epithelium is critical to the lifestyle of the ubiquitous parasite Giardia lamblia. The microtubule cytoskeleton plays a well characterized role in attachment via the ventral adhesive disc, whereas the role of the unconventional actin cytoskeleton is controversial. We identified a novel actin associated protein with putative WH2-like actin binding domains we named Flangin. Flangin complexes with Giardia actin and is enriched in the ventrolateral flange (VLF), a lamellipodium-like membrane protrusion at the interface between parasites and attached surfaces. Live imaging revealed that the VLF grows to ~1 μm in width after cytokinesis, then remains size-uniform in interphase, grows during mitosis, and is resorbed during cytokinesis. A Flangin truncation mutant stabilizes the VLF and blocks cytokinesis, indicating that the VLF is a membrane reservoir supporting rapid myosin-independent cytokinesis in Giardia. Rho family GTPases are important regulators of membrane protrusions, GlRac, the sole Rho family GTPase in Giardia, was localized to the VLF. Knockdown of Flangin, actin, and GlRac result in VLF formation defects indicating a conserved role for GlRac and actin in forming membrane protrusions, despite the absence of canonical actin binding proteins that link Rho GTPase signaling to lamellipodia formation. Flangin-depleted parasites challenged with fluid shear force in flow chambers had a reduced ability to remain attached, indicating a role for the VLF in attachment. This secondary attachment mechanism complements the microtubule based adhesive ventral disc, a feature that is particularly important during mitosis when the parental ventral disc begins disassembly in preparation for cytokinesis.ImportanceThe ventrolateral flange (VLF) is a lamellipodium-like structure found at the host-parasite interface that has long been thought to be involved in parasite attachment. The proteins responsible for building the VLF have remained unidentified precluding manipulation of the VLF to determine its role in Giardia biology. We identified Flangin, a novel actin associated protein that localizes to the VLF, implicating Giardia actin in VLF formation. We demonstrate that: 1.) Flangin, actin, and GlRac are required for VLF formation, 2.) the VLF serves as a membrane reservoir to support Giardia’s incredibly fast cytokinesis, and 3) the VLF augments attachment, which is critical to parasitism. The microtubule-based adhesive ventral disc and the actin-based ventrolateral flange represent redundant means of maintaining attachment, the presence of redundant systems illustrate the importance of attachment to the lifestyle of this ubiquitous parasite.

show abstract

“…However, there is no indication that nucleosome component glycylation regulates BB organization. Moreover, Giardia TTLL3 polygylcylates C-terminal glutamate residues on 14-3-3 (epsilon-like) that regulates actin organization (Lalle et al, 2011, Lalle et al, 2006, Krtkova et al, 2017). A Tetrahymena 14-3-3, Ftt18, was previously reported at BBs and pcMTs (Kilburn et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Microtubule glycylation promotes basal body attachment to the cell cortex

Junker

Soh

O’Toole

et al. 2019

Preprint

View full text Add to dashboard Cite

STATEMENTBasal bodies position motile cilia at the cell cortex. This study finds tubulin glycylation to promote BB-associated microtubule elongation and structural attachment of basal bodies to the cell's cortical cytoskeleton. ABSTRACTMotile cilia generate directed hydrodynamic flow that is important for the motility of cells and extracellular fluids. To optimize directed hydrodynamic flow, motile cilia are organized and oriented into a polarized array. Basal bodies (BB) nucleate and position motile cilia at the cell cortex. Cytoplasmic BB-associated microtubules are conserved structures that extend from BBs. Using the ciliate, Tetrahymena thermophila, combined with EM-tomography and light microscopy, we show that BB-appendage microtubules assemble coincident with new BB assembly and are attached to the cell cortex. These BB-appendage microtubules are specifically marked with post translational modifications of tubulin, including glycylation. Mutations that prevent glycylation shorten BB-appendage microtubules and disrupt BB positioning and cortical attachment. Consistent with the attachment of BB-appendage microtubules to the cell cortex for BB positioning, mutations that disrupt the cellular cortical cytoskeleton similarly disrupt the cortical attachment and positioning of BBs. In summary, BBappendage microtubules promote the organization of ciliary arrays through attachment to the cell cortex.

show abstract

14-3-3 Regulates Actin Filament Formation in the Deep-Branching Eukaryote Giardia lamblia

Cited by 18 publications

References 56 publications

Microtubule glycylation promotes attachment of basal bodies to the cell cortex

Microtubule glycylation promotes attachment of basal bodies to the cell cortex

TheGiardialamellipodium-like ventrolateral flange supports attachment and rapid cytokinesis

Microtubule glycylation promotes basal body attachment to the cell cortex

Contact Info

Product

Resources

About