scholarly journals Myosin XI Is Essential for Tip Growth in Physcomitrella patens

2010 ◽  
Vol 22 (6) ◽  
pp. 1868-1882 ◽  
Author(s):  
Luis Vidali ◽  
Graham M. Burkart ◽  
Robert C. Augustine ◽  
Erin Kerdavid ◽  
Erkan Tüzel ◽  
...  
Keyword(s):  
Tip Growth ◽  
Physcomitrella Patens ◽  
Myosin Xi

Microtubules and microfilaments in tip growth: evidence that microtubules impose polarity on protonemal growth in Physcomitrella patens

1988 ◽  
Vol 89 (4) ◽  
pp. 533-540 ◽  
Author(s):  
J. H. DOONAN ◽  
D. J. COVE ◽  
C. W. LLOYD
Keyword(s):  
Tip Growth ◽  
Physcomitrella Patens ◽  
Cytochalasin D ◽  
Immunofluorescence Study ◽  
Apical Dome ◽  
High Concentrations ◽  
Cytoskeletal Elements ◽  
Drug Studies ◽  
Tip Cells ◽  
Cytoskeletal Drugs

In this study we compare the contributions of Factin and microtubules to tip growth in filamentous cells of the moss Physcomitrella patens. In tip growth, expansion seems to be restricted to the hemispherical apical dome. Cytoskeletal elements have been suspected, from drug studies, to be involved in this but electron microscopy has generally not confirmed the presence of an apical cytoskeleton. However, in a previous immunofluorescence study we reported that microtubules could be seen to focus upon the apical dome in tip cells of the moss P. patens. In the present investigation F-actin has also been detected at the apices of these cells. Anti-cytoskeletal drugs were therefore used to differentiate between the roles of actin filaments and microtubules in tip growth. At high concentrations (30μM), the herbicide cremart de-polymerized microtubules and caused tip swelling. F-actin was still present under such conditions but its fragmentation by cytochalasin D suppressed this herbicide-induced swelling. On its own, cytochalasin D arrested tip growth without causing swollen tips. At lower concentrations, cremart disorganized microtubules rather than causing their complete depolymerization. Under these conditions, new but swollen growing points were initiated along the filament. The addition of taxol to cremart-treated filaments tended to reduce swelling and to re-polarize outgrowth. With particular combinations of these drugs, multiple lateral out-growths were initiated in the vicinity of the nucleus. It is concluded: (1) that F-actin is present at the tips of Physcomitrella caulonemal apical cells; (2) that unfragmented F-actin is necessary for outgrowth; (3) that even disorganized microtubules permit some degree of outgrowth but that an unperturbed distribution of axial microtubules, focussing upon an apex, is essential in order to impose tubular shape and directionality upon expansion.

scholarly journals Systematic survey of the function of ROP regulators and effectors during tip growth in the moss Physcomitrella patens

2018 ◽  
Vol 70 (2) ◽  
pp. 447-457 ◽  
Author(s):  
Carlisle Bascom ◽  
Graham M Burkart ◽  
Darren R Mallett ◽  
Jacquelyn E O’Sullivan ◽  
Alexis J Tomaszewski ◽  
...  
Keyword(s):  
Tip Growth ◽  
Physcomitrella Patens ◽  
Systematic Survey

scholarly journals Physcomitrella patens: a model to investigate the role of RAC/ROP GTPase signalling in tip growth

2010 ◽  
Vol 61 (7) ◽  
pp. 1917-1937 ◽  
Author(s):  
D. Magnus Eklund ◽  
Emma M. Svensson ◽  
Benedikt Kost
Keyword(s):  
Tip Growth ◽  
Physcomitrella Patens ◽  
Rop Gtpase

scholarly journals Myosin XI Interacting with a RabE GTPase Is Required for Polarized Growth

2019 ◽  
Author(s):  
Robert G. Orr ◽  
Fabienne Furt ◽  
Erin L. Warner ◽  
Erin M. Agar ◽  
Jennifer M. Garbarino ◽  
...  
Keyword(s):  
Cell Division ◽  
Molecular Motors ◽  
Physcomitrella Patens ◽  
Single Cells ◽  
Polarized Growth ◽  
Yeast Two Hybrid ◽  
Growing Cell ◽  
Cross Correlation Analysis ◽  
Myosin Xi ◽  
Two Hybrid

AbstractThe fundamental eukaryotic process of intracellular trafficking requires the interconnected activity of molecular motors trafficking vesicular cargo within a dynamic cytoskeletal network. However, in plants, few mechanistic details are known about how molecular motors associate with their secretory cargo to support the ubiquitous processes of polarized growth and cell division. A yeast two-hybrid screen of a Physcomitrella patens library identified a RabE GTPase as an interactor of myosin XI and subsequently demonstrated all five RabE members interact with myosin XI. Consistent with a role in polarized transport, we observed RabE at the growing cell apex and at the expanding cell plate during cell division. An in vivo cross-correlation analysis of fluorescently tagged RabE and myosin XI revealed that both species are spatiotemporally coupled, demonstrating their simultaneous involvement in polarized growth. To determine if myosin XI and RabE are directly coupled, we first computationally predicted myosin XI:RabE interface through a homology modeling-directed approach. We identified a structurally conserved residue on myosin XI, V1422, that when mutated abolished RabE binding in the yeast two-hybrid system and resulted in unpolarized plants instead of the characteristic network of filamentous cells when regenerated from single cells. Together, this work demonstrates the requirement of a direct myosin XI:RabE interaction for polarized growth in plants.

scholarly journals In vivo Interactions between Myosin XI, Vesicles, and Filamentous Actin Are Fast and Transient

2019 ◽  
Author(s):  
Jeffrey P. Bibeau ◽  
Fabienne Furt ◽  
S. Iman Mousavi ◽  
James L. Kingsley ◽  
Max F. Levine ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Physcomitrella Patens ◽  
Epifluorescence Microscopy ◽  
Markov Modeling ◽  
Filamentous Actin ◽  
Hidden Markov Modeling ◽  
Short Run ◽  
Myosin Xi ◽  
Run Lengths

AbstractThe apical actin cytoskeleton and active membrane trafficking machinery are essential in driving polarized cell growth. To better understand the interactions between myosin XI, vesicles, and actin filament in vivo, we performed Fluorescence Recovery After Photobleaching (FRAP) and showed that the dynamics of myosin XIa at the tip are actin-dependent and that approximately half of myosin XI is bound to vesicles in the cell. To obtain single particle information, we used Variable Angle Epifluorescence Microscopy (VAEM) in Physcomitrella patens protoplasts to demonstrate that myosin XIa and VAMP72-labeled vesicles localize in time and space for periods lasting only a few seconds. Using tracking data with Hidden Markov Modeling (HMM), we showed that myosin XIa and VAMP72-labeled vesicles exhibit short runs of actin-dependent directed transport. We also found that the interaction of myosin XI with vesicles is short lived. Together, this bound fraction, fast off-rate, and short run lengths are expected to be critical for the dynamic oscillations observed at the cell apex, and may be vital for the regulation and recycling of the exocytosis machinery; while simultaneously promoting the vesicle focusing and secretion at the tip, necessary for cell wall expansion.

scholarly journals In vivo interactions between myosin XI, vesicles and filamentous actin are fast and transient in Physcomitrella patens

2020 ◽  
Vol 133 (4) ◽  
pp. jcs234682 ◽  
Author(s):  
Jeffrey P. Bibeau ◽  
Fabienne Furt ◽  
S. Iman Mousavi ◽  
James L. Kingsley ◽  
Max F. Levine ◽  
...  
Keyword(s):  
Physcomitrella Patens ◽  
Filamentous Actin ◽  
Myosin Xi

scholarly journals Hydroxyproline O ‐arabinosyltransferase mutants oppositely alter tip growth in Arabidopsis thaliana and Physcomitrella patens

2015 ◽  
Vol 85 (2) ◽  
pp. 193-208 ◽  
Author(s):  
Cora A. MacAlister ◽  
Carlos Ortiz‐Ramírez ◽  
Jörg D. Becker ◽  
José A. Feijó ◽  
Zachary B. Lippman
Keyword(s):  
Arabidopsis Thaliana ◽  
Tip Growth ◽  
Physcomitrella Patens

scholarly journals Kinesins Have a Dual Function in Organizing Microtubules during Both Tip Growth and Cytokinesis in Physcomitrella patens

2014 ◽  
Vol 26 (3) ◽  
pp. 1256-1266 ◽  
Author(s):  
Yuji Hiwatashi ◽  
Yoshikatsu Sato ◽  
John H. Doonan
Keyword(s):  
Tip Growth ◽  
Physcomitrella Patens ◽  
Dual Function

scholarly journals KCH kinesin drives nuclear transport and cytoskeletal coalescence for tip cell growth

2018 ◽  
Author(s):  
Moé Yamada ◽  
Gohta Goshima
Keyword(s):  
Tip Growth ◽  
Physcomitrella Patens ◽  
Focal Point ◽  
Nuclear Transport ◽  
Apical Cell ◽  
Cytoplasmic Dynein ◽  
Long Distance ◽  
Long Distance Transport ◽  
Genes Encoding ◽  
Distance Transport

Long-distance transport along microtubules (MTs) is critical for intracellular organisation. In animals, antagonistic motor proteins kinesin (plus end-directed) and dynein (minus end-directed) drive cargo transport. In land plants, however, the identity of motors responsible for transport is poorly understood, as genes encoding cytoplasmic dynein are missing. How other functions of dynein are brought about in plants also remains unknown. Here, we show that a subclass of the kinesin-14 family, KCH—which can also bind actin—drives MT minus end-directed nuclear transport in the moss Physcomitrella patens. When all four KCH genes were deleted, the nucleus was not maintained in the cell centre but was translocated to the apical end of protonemal cells. In the knockout (KO) line, apical cell tip growth was also severely suppressed. KCH was localised on MTs, including at the MT focal point near the tip where MT plus ends coalesced with actin filaments. MT focus was not persistent in KCH KO lines, whereas actin destabilisation also disrupted the focus despite KCH remaining on unfocused MTs. Functions of nuclear transport and tip growth were distinct, as a truncated KCH construct restored nuclear transport activity but not tip growth retardation of the KO line. Thus, our study identified KCH as a long-distance retrograde transporter as well as a cytoskeletal crosslinker, reminiscent of the versatile animal dynein.

scholarly journals The COPII components Sec23 and Sec24 form isoform specific subcomplexes with Sec23D/E and Sec24C/D essential for tip growth

2020 ◽  
Author(s):  
Mingqin Chang ◽  
Shu-Zon Wu ◽  
Jacquelyn E. O’Sullivan ◽  
Magdalena Bezanilla
Keyword(s):  
Plasma Membrane ◽  
Tip Growth ◽  
Physcomitrella Patens ◽  
Gene Families ◽  
Vesicle Traffic ◽  
Genes Encoding ◽  
Er Exit Sites

AbstractCOPII, a coat of proteins that form vesicles on the ER, mediates vesicle traffic from the ER to the Golgi. In contrast to metazoans that have few genes encoding each COPII component, plants have expanded these gene families leading to the hypothesis that plant COPII has functionally diversified. Here, we analyzed the gene families encoding for the Sec23/24 heterodimer in the moss Physcomitrium (Physcomitrella) patens. In P. patens, Sec23 and Sec24 gene families are each comprised of seven genes. We discovered that Sec23D is functionally redundant with Sec23E and together they are essential for protonemal development. Sec23D is critical for secretion to the Golgi and the plasma membrane in tip growing protonemata. Sec23D preferentially associates with Sec24C/D, also essential for protonemata. In contrast, the remaining five Sec23 genes are dispensable for tip growth, but are redundant with Sec23D/E for gametophore formation. While Sec23A/B/C/F/G do not quantitatively affect Golgi secretion in protonemata, they do contribute to secretion to the plasma membrane. Furthermore, the three highly expressed Sec23 genes in protonemata, Sec23B/D/G form morphologically distinct ER exit sites. These data suggest that Sec23D/E form unique ER exit sites contributing to secretion that is essential for tip growing protonemata.

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