A protein phosphatase 2A complex spatially controls plant cell division

Area of Science:

• Plant Cell Biology
• Cytoskeleton Dynamics
• Molecular Evolution

Background:

• Cell division plane orientation is critical for plant body plan determination, especially without cell migration.
• The preprophase band, a transient cytoskeletal array, establishes the division plane in plant cells.
• Understanding the regulation of microtubule organization during the cell cycle is essential.

Purpose of the Study:

• To identify and characterize protein complexes involved in regulating the plant microtubule cytoskeleton.
• To elucidate the mechanism by which protein phosphatase 2A (PP2A) activity is targeted to microtubules.
• To explore potential evolutionary links between plant cytoskeletal components and animal microtubule organizing centers.

Main Methods:

• Biochemical analysis to identify protein complex composition.
• Microscopy techniques to visualize cytoskeletal arrays and protein localization.
• Comparative analysis of protein sequences to identify evolutionary relationships.

Main Results:

• A novel protein complex comprising TONNEAU1 and a PP2A heterotrimeric holoenzyme (with FASS) was identified.
• This complex targets PP2A activity to microtubules, regulating the transition to the premitotic microtubule array.
• Recruitment to the cytoskeleton is mediated by TONNEAU1-recruiting motif family proteins.
• Key components of this complex show similarity to animal centrosomal proteins, despite plants lacking centrosomes.

Conclusions:

• The identified protein complex plays a crucial role in orienting plant cell division by regulating microtubule organization.
• This discovery reveals an evolutionary link between the plant cortical cytoskeleton and microtubule organizing centers in other eukaryotes.
• The findings provide insights into the conserved mechanisms governing cell division and cytoskeletal regulation across diverse life forms.