Woronin body hitchhiking on early endosomes is dispensable for septal localization in <i>Aspergillus nidulans</i>

Songster, Livia D; Bhuyan, Devahuti; Christensen, Jenna R; Reck-Peterson, Samara L.

doi:10.1091/mbc.e23-01-0025

Cited by 4 publications

References 55 publications

(97 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

Aspergillus SUMOylation mutants exhibit chromosome segregation defects including chromatin bridges

Zhang,

Qiu,

Bieger

et al. 2023

Genetics

View full text Add to dashboard Cite

Functions of protein SUMOylation remain incompletely understood in different cell types. Via forward genetics, here we identified ubaBQ247*, a loss-of-function mutation in a SUMO-activation enzyme UbaB in the filamentous fugus Aspergillus nidulans. The ubaBQ247*, ΔubaB and ΔsumO mutants all produce abnormal chromatin bridges, indicating the importance of SUMOylation in the completion of chromosome segregation. The bridges are enclosed by nuclear membrane containing peripheral nuclear-pore-complex proteins that normally get dispersed during mitosis, and the bridges are also surrounded by cytoplasmic microtubules typical of interphase cells. Time-lapse sequences further indicate that most bridges persist through interphase prior to the next mitosis, and anaphase chromosome segregation can produce new bridges that persist into the next interphase. When the first mitosis happens at a higher temperature of 42°C, SUMOylation deficiency produces not only chromatin bridges but also many abnormally shaped single nuclei that fail to divide. UbaB-GFP localizes to interphase nuclei just like the previously studied SumO-GFP, but the nuclear signals disappear during mitosis when the nuclear pores are partially open, and the signals reappear after mitosis. The nuclear localization is consistent with many SUMO-targets being nuclear proteins. Finally, although the budding yeast SUMOylation machinery interacts with LIS1, a protein critical for dynein activation, loss of SUMOylation does not cause any obvious defect in dynein-mediated transport of nuclei and early endosomes, indicating that SUMOylation is unnecessary for dynein activation in A. nidulans.

show abstract

Aspergillus SUMOylation mutants exhibit chromosome segregation defects including chromatin bridges

Zhang,

Qiu,

Bieger

et al. 2023

Genetics

View full text Add to dashboard Cite

show abstract

Aspergillus SUMOylation mutants have normal dynein function but exhibit chromatin bridges

Zhang

Qiu

Bieger

et al. 2023

Preprint

View full text Add to dashboard Cite

Functions of protein SUMOylation remain incompletely understood in different cell types. The budding yeast SUMOylation machinery interacts with LIS1, a protein critical for dynein activation, but dynein-pathway components were not identified as SUMO-targets in the filamentous fungus Aspergillus nidulans. Via A. nidulans forward genetics, here we identified ubaBQ247*, a loss-of-function mutation in a SUMO-activation enzyme UbaB. Colonies of the ubaBQ247*, ∆ubaB and ∆sumO mutants looked similar and less healthy than the wild-type colony. In these mutants, about 10% of nuclei are connected by abnormal chromatin bridges, indicating the importance of SUMOylation in the completion of chromosome segregation. Nuclei connected by chromatin bridges are mostly in interphase, suggesting that these bridges do not prevent cell-cycle progression. UbaB-GFP localizes to interphase nuclei just like the previously studied SumO-GFP, but the nuclear signals disappear during mitosis when the nuclear pores are partially open, and the signals reappear after mitosis. The nuclear localization is consistent with many SUMO-targets being nuclear proteins, for example, topoisomerase II whose SUMOylation defect gives rise to chromatin bridges in mammalian cells. Unlike in mammalian cells, however, loss of SUMOylation in A. nidulans does not apparently affect the metaphase-to-anaphase transition, further highlighting differences in the requirements of SUMOylation in different cell types. Finally, loss of UbaB or SumO does not affect dynein- and LIS1-mediated early-endosome transport, indicating that SUMOylation is unnecessary for dynein or LIS1 function in A. nidulans.

show abstract

VezA/vezatin facilitates proper assembly of the dynactin complex in vivo

Zhang,

Qiu,

Xie

et al. 2024

Preprint

View full text Add to dashboard Cite

Cytoplasmic dynein-mediated intracellular transport needs the multi-component dynactin complex for cargo binding and motor activation. However, cellular factors involved in dynactin assembly remain unexplored. Here we found in Aspergillus nidulans that the vezatin homolog VezA is important for dynactin assembly. VezA affects the microtubule plus-end accumulation of dynein before cargo binding and cargo adapter-mediated dynein activation, two processes that both need dynactin. The dynactin complex contains multiple components including an Arp1 (actin-related protein 1) mini-filament associated with a pointed-end sub-complex. VezA physically interacts with dynactin either directly or indirectly via the Arp1 mini-filament and its pointed-end sub-complex. Loss of VezA causes a defect in dynactin integrity, most likely by affecting the connection between the Arp1 mini-filament and its pointed-end sub-complex. Using various dynactin mutants, we further revealed that assembly of the dynactin complex must be highly coordinated. Together, these results shed important new light on dynactin assembly in vivo.

show abstract

Woronin body hitchhiking on early endosomes is dispensable for septal localization in Aspergillus nidulans

Cited by 4 publications

References 55 publications

Aspergillus SUMOylation mutants exhibit chromosome segregation defects including chromatin bridges

Aspergillus SUMOylation mutants exhibit chromosome segregation defects including chromatin bridges

Aspergillus SUMOylation mutants have normal dynein function but exhibit chromatin bridges

VezA/vezatin facilitates proper assembly of the dynactin complex in vivo

Contact Info

Product

Resources

About