scholarly journals An anchoring complex recruits katanin for microtubule severing at the plant cortical nucleation sites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Noriyoshi Yagi ◽  
Takehide Kato ◽  
Sachihiro Matsunaga ◽  
David W. Ehrhardt ◽  
Masayoshi Nakamura ◽  
...  
Keyword(s):  
Protein Complex ◽  
Plant Cells ◽  
Tight Control ◽  
Microtubule Nucleation ◽  
Genetic Studies ◽  
Microtubule Severing ◽  
Nucleation Sites ◽  
Evolutionarily Conserved ◽  
Arabidopsis Cells ◽  
Dynamic Microtubule

AbstractMicrotubules are severed by katanin at distinct cellular locations to facilitate reorientation or amplification of dynamic microtubule arrays, but katanin targeting mechanisms are poorly understood. Here we show that a centrosomal microtubule-anchoring complex is used to recruit katanin in acentrosomal plant cells. The conserved protein complex of Msd1 (also known as SSX2IP) and Wdr8 is localized at microtubule nucleation sites along the microtubule lattice in interphase Arabidopsis cells. Katanin is recruited to these sites for efficient release of newly formed daughter microtubules. Our cell biological and genetic studies demonstrate that Msd1-Wdr8 acts as a specific katanin recruitment factor to cortical nucleation sites (but not to microtubule crossover sites) and stabilizes the association of daughter microtubule minus ends to their nucleation sites until they become severed by katanin. Molecular coupling of sequential anchoring and severing events by the evolutionarily conserved complex renders microtubule release under tight control of katanin activity.

scholarly journals The plant Spc98p homologue colocalizes with γ-tubulin at microtubule nucleation sites and is required for microtubule nucleation

2002 ◽  
Vol 115 (11) ◽  
pp. 2423-2431 ◽  
Author(s):  
Mathieu Erhardt ◽  
Virginie Stoppin-Mellet ◽  
Sarah Campagne ◽  
Jean Canaday ◽  
Jérôme Mutterer ◽  
...  
Keyword(s):  
Spindle Pole Body ◽  
Plant Cells ◽  
Spindle Pole ◽  
Cell Cortex ◽  
Nuclear Surface ◽  
Animal Cells ◽  
Microtubule Nucleation ◽  
Higher Plant ◽  
Nucleation Sites

The molecular basis of microtubule nucleation is still not known in higher plant cells. This process is better understood in yeast and animals cells. In the yeast spindle pole body and the centrosome in animal cells,γ-tubulin small complexes and γ-tubulin ring complexes,respectively, nucleate all microtubules. In addition to γ-tubulin,Spc98p or its homologues plays an essential role. We report here the characterization of rice and Arabidopsis homologues of SPC98. Spc98p colocalizes with γ-tubulin at the nuclear surface where microtubules are nucleated on isolated tobacco nuclei and in living cells. AtSpc98p-GFP also localizes at the cell cortex. Spc98p is not associated with γ-tubulin along microtubules. These data suggest that multiple microtubule-nucleating sites are active in plant cells. Microtubule nucleation involving Spc98p-containing γ-tubulin complexes could then be conserved among all eukaryotes, despite differences in structure and spatial distribution of microtubule organizing centers.

scholarly journals Humanizing the yeast origin recognition complex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Clare S. K. Lee ◽  
Ming Fung Cheung ◽  
Jinsen Li ◽  
Yongqian Zhao ◽  
Wai Hei Lam ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Complex ◽  
Origin Recognition Complex ◽  
Specific Binding ◽  
Life Cycles ◽  
Amino Acid Insertion ◽  
Evolutionarily Conserved ◽  
Transcriptional Start Sites ◽  
Eukaryote Genome ◽  
Origin Recognition

AbstractThe Origin Recognition Complex (ORC) is an evolutionarily conserved six-subunit protein complex that binds specific sites at many locations to coordinately replicate the entire eukaryote genome. Though highly conserved in structure, ORC’s selectivity for replication origins has diverged tremendously between yeasts and humans to adapt to vastly different life cycles. In this work, we demonstrate that the selectivity determinant of ORC for DNA binding lies in a 19-amino acid insertion helix in the Orc4 subunit, which is present in yeast but absent in human. Removal of this motif from Orc4 transforms the yeast ORC, which selects origins based on base-specific binding at defined locations, into one whose selectivity is dictated by chromatin landscape and afforded with plasticity, as reported for human. Notably, the altered yeast ORC has acquired an affinity for regions near transcriptional start sites (TSSs), which the human ORC also favors.

scholarly journals Atypical Protein Kinase C Is Involved in the Evolutionarily Conserved Par Protein Complex and Plays a Critical Role in Establishing Epithelia-Specific Junctional Structures

2001 ◽  
Vol 152 (6) ◽  
pp. 1183-1196 ◽  
Author(s):  
Atsushi Suzuki ◽  
Tomoyuki Yamanaka ◽  
Tomonori Hirose ◽  
Naoyuki Manabe ◽  
Keiko Mizuno ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Polarity ◽  
Protein Complex ◽  
Mdck Cells ◽  
Critical Role ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Surface Polarity ◽  
C Elegans ◽  
Evolutionarily Conserved

We have previously shown that during early Caenorhabditis elegans embryogenesis PKC-3, a C. elegans atypical PKC (aPKC), plays critical roles in the establishment of cell polarity required for subsequent asymmetric cleavage by interacting with PAR-3 [Tabuse, Y., Y. Izumi, F. Piano, K.J. Kemphues, J. Miwa, and S. Ohno. 1998. Development (Camb.). 125:3607–3614]. Together with the fact that aPKC and a mammalian PAR-3 homologue, aPKC-specific interacting protein (ASIP), colocalize at the tight junctions of polarized epithelial cells (Izumi, Y., H. Hirose, Y. Tamai, S.-I. Hirai, Y. Nagashima, T. Fujimoto, Y. Tabuse, K.J. Kemphues, and S. Ohno. 1998. J. Cell Biol. 143:95–106), this suggests a ubiquitous role for aPKC in establishing cell polarity in multicellular organisms. Here, we show that the overexpression of a dominant-negative mutant of aPKC (aPKCkn) in MDCK II cells causes mislocalization of ASIP/PAR-3. Immunocytochemical analyses, as well as measurements of paracellular diffusion of ions or nonionic solutes, demonstrate that the biogenesis of the tight junction structure itself is severely affected in aPKCkn-expressing cells. Furthermore, these cells show increased interdomain diffusion of fluorescent lipid and disruption of the polarized distribution of Na+,K+-ATPase, suggesting that epithelial cell surface polarity is severely impaired in these cells. On the other hand, we also found that aPKC associates not only with ASIP/PAR-3, but also with a mammalian homologue of C. elegans PAR-6 (mPAR-6), and thereby mediates the formation of an aPKC-ASIP/PAR-3–PAR-6 ternary complex that localizes to the apical junctional region of MDCK cells. These results indicate that aPKC is involved in the evolutionarily conserved PAR protein complex, and plays critical roles in the development of the junctional structures and apico-basal polarization of mammalian epithelial cells.

EB1 reveals mobile microtubule nucleation sites in Arabidopsis

2003 ◽  
Vol 5 (11) ◽  
pp. 967-971 ◽  
Author(s):  
Jordi Chan ◽  
Grant M. Calder ◽  
John H. Doonan ◽  
Clive W. Lloyd
Keyword(s):  
Microtubule Nucleation ◽  
Nucleation Sites

scholarly journals A fungal effector targets a heat shock–dynamin protein complex to modulate mitochondrial dynamics and reduce plant immunity

2020 ◽  
Vol 6 (48) ◽  
pp. eabb7719
Author(s):  
Guojuan Xu ◽  
Xionghui Zhong ◽  
Yanlong Shi ◽  
Zhuo Liu ◽  
Nan Jiang ◽  
...  
Keyword(s):  
Transgenic Rice ◽  
Protein Complex ◽  
Fungal Pathogen ◽  
Mitochondrial Dynamics ◽  
Plant Immunity ◽  
Mitochondrial Fission ◽  
Plant Cells ◽  
Related Protein ◽  
Dnaj Protein ◽  
Enhanced Resistance

Mitochondria are essential for animal and plant immunity. Here, we report that the effector MoCDIP4 of the fungal pathogen Magnaporthe oryzae targets the mitochondria-associated OsDjA9-OsDRP1E protein complex to reduce rice immunity. The DnaJ protein OsDjA9 interacts with the dynamin-related protein OsDRP1E and promotes the degradation of OsDRP1E, which functions in mitochondrial fission. By contrast, MoCDIP4 binds OsDjA9 to compete with OsDRP1E, resulting in OsDRP1E accumulation. Knockout of OsDjA9 or overexpression of OsDRP1E or MoCDIP4 in transgenic rice results in shortened mitochondria and enhanced susceptibility to M. oryzae. Overexpression of OsDjA9 or knockout of OsDRP1E in transgenic rice, in contrast, leads to elongated mitochondria and enhanced resistance to M. oryzae. Our study therefore reveals a previously unidentified pathogen-infection strategy in which the pathogen delivers an effector into plant cells to target an HSP40-DRP complex; the targeting leads to the perturbation of mitochondrial dynamics, thereby inhibiting mitochondria-mediated plant immunity.

scholarly journals Alp7-Mto1 and Alp14 synergize to promote interphase microtubule regrowth from the nuclear envelope

2019 ◽  
Vol 11 (11) ◽  
pp. 944-955 ◽  
Author(s):  
Wenyue Liu ◽  
Fan Zheng ◽  
Yucai Wang ◽  
Chuanhai Fu
Keyword(s):  
Nuclear Envelope ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Microtubule Assembly ◽  
Dependent Manner ◽  
Microtubule Nucleation ◽  
Microtubule Organizing Centers ◽  
Evolutionarily Conserved ◽  
Microtubule Growth ◽  
In Cells

Abstract Microtubules grow not only from the centrosome but also from various noncentrosomal microtubule-organizing centers (MTOCs), including the nuclear envelope (NE) and pre-existing microtubules. The evolutionarily conserved proteins Mto1/CDK5RAP2 and Alp14/TOG/XMAP215 have been shown to be involved in promoting microtubule nucleation. However, it has remained elusive as to how the microtubule nucleation promoting factors are specified to various noncentrosomal MTOCs, particularly the NE, and how these proteins coordinate to organize microtubule assembly. Here, we demonstrate that in the fission yeast Schizosaccharomyces pombe, efficient interphase microtubule growth from the NE requires Alp7/TACC, Alp14/TOG/XMAP215, and Mto1/CDK5RAP2. The absence of Alp7, Alp14, or Mto1 compromises microtubule regrowth on the NE in cells undergoing microtubule repolymerization. We further demonstrate that Alp7 and Mto1 interdependently localize to the NE in cells without microtubules and that Alp14 localizes to the NE in an Alp7 and Mto1-dependent manner. Tethering Mto1 to the NE in cells lacking Alp7 partially restores microtubule number and the efficiency of microtubule generation from the NE. Hence, our study delineates that Alp7, Alp14, and Mto1 work in concert to regulate interphase microtubule regrowth on the NE.

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