Systematic Localization of the Arabidopsis Core Cell Cycle Proteins Reveals Novel Cell Division Complexes

Joanna Boruc,Pierre Hilson,Rebecca De Clercq,Daniel Van Damme,Evelien Mylle,Danny Geelen,Dirk Inzeݩ,Stephane Rombauts,Maria Duda,Eugenia Russinova

doi:10.1104/pp.109.148643

Abstract

Cell division depends on the correct localization of the cyclin-dependent kinases that are regulated by phosphorylation, cyclin proteolysis, and protein-protein interactions. Although immunological assays can define cell cycle protein abundance and localization, they are not suitable for detecting the dynamic rearrangements of molecular components during cell division. Here, we applied an in vivo approach to trace the subcellular localization of 60 Arabidopsis (Arabidopsis thaliana) core cell cycle proteins fused to green fluorescent proteins during cell division in tobacco (Nicotiana tabacum) and Arabidopsis. Several cell cycle proteins showed a dynamic association with mitotic structures, such as condensed chromosomes and the preprophase band in both species, suggesting a strong conservation of targeting mechanisms. Furthermore, colocalized proteins were shown to bind in vivo, strengthening their localization-function connection. Thus, we identified unknown spatiotemporal territories where functional cell cycle protein interactions are most likely to occur.

Highlights

Cell division depends on the correct localization of the cyclin-dependent kinases that are regulated by phosphorylation, cyclin proteolysis, and protein-protein interactions
We show that KRP1 and KRP4 associated with CDKA;1 and that the complex localized to the chromosomes during cell division
The selected proteins included 57 previously annotated core cell cycle proteins (Vandepoele et al, 2002) and three proteins recently implicated in cell cycle control, namely CCS52A2, CCS52B, and CDKG;2 (Fulop et al, 2005; Menges et al, 2005)

Summary

Introduction

Cell division depends on the correct localization of the cyclin-dependent kinases that are regulated by phosphorylation, cyclin proteolysis, and protein-protein interactions. The passage through successive cell cycle phases is controlled by CDKs (CDKA; in Arabidopsis [Arabidopsis thaliana]; Nigg, 1995) that are activated mainly upon binding of regulatory proteins (such as cyclins) and phosphorylation (Jeffrey et al, 1995; Russo et al, 1996). In tobacco (Nicotiana tabacum), Medicago, and Arabidopsis, the A2-type and A3-type cyclins localized to the interphase nucleus (Criqui et al, 2001; Yu et al, 2003; Imai et al, 2006). The cytoplasmic in interphase B1-type cyclins localized to the nucleus as cells entered mitosis, associated with the chromosomes during prophase, and were destroyed after metaphase (Criqui et al, 2001). Plant KRPs localize to the nucleus in interphase, with KRP1, KRP3, KRP4, and KRP5 displaying a subnuclear punctate pattern of distribution (Jasinski et al, 2002; Zhou et al, 2003; Weinl et al, 2005; Bird et al, 2007)

Methods

Results

Conclusion