A molecular view of plant centromeres

 

Jiang J, Birchler JA, Parrott WA, Dawe RK. A molecular view of plant centromeres. Trends Plant Sci. 2003 Dec; 8 (12): 570-5

 

Although plants were the organisms of choice in several classical centromere studies, molecular and biochemical studies of plant centromeres have lagged behind those in model animal species. However, in the past several years, several centromeric repetitive DNA elements have been isolated in plant species and their roles in centromere function have been demonstrated. Most significantly, a Ty3/gypsy class of centromere-specific retrotransposons, the CR family, was discovered in the grass species. The CR elements are highly enriched in chromatin domains associated with CENH3, the centromere-specific histone H3 variant. CR elements as well as their flanking centromeric satellite DNA are actively transcribed in maize. These data suggest that the deposition of centromeric histones might be a transcription-coupled event.

A molecular view of plant centromeres

DNA and proteins of plant centromeres

 

Houben A, Schubert I. DNA and proteins of plant centromeres. Curr Opin Plant Biol. 2003 Dec; 6 (6): 554-60

 

In plants, as in all eukaryotes, centromeres are chromatin domains that govern the transmission of nuclear chromosomes to the next generation of cells/individuals. The DNA composition and sequence organization of centromeres has recently been elucidated for a few plant species. Although there is little sequence conservation among centromeres, they usually contain tandem repeats and retroelements. The occurrence of neocentromeres reinforces the idea that the positions of centromeres are determined epigenetically. In contrast to centromeric DNA, structural and transient kinetochoric proteins are highly conserved among eukaryotes. Candidate sequences have been identified for a dozen putative kinetochore protein homologues, and some have been localized to plant centromeres. The kinetochore protein CENH3, which substitutes histone H3 within centromeric nucleosomes, co-immunoprecipitates preferentially with centromeric sequences. The mechanism(s) of centromere assembly and the functional implication of (peri-)centromeric modifications of chromatin remain to be elucidated.

DNA and proteins of plant centromeres

The rapidly evolving field of plant centromeres

 

Hall AE, Keith KC, Hall SE, Copenhaver GP, Preuss D. The rapidly evolving field of plant centromeres. Curr Opin Plant Biol. 2004 Apr;7(2):108-14

 

Meiotic and mitotic chromosome segregation are highly conserved in eukaryotic organisms, yet centromeres--the chromosomal sites that mediate segregation--evolve extremely rapidly. Plant centromeres have DNA elements that are shared across species, yet they diverge rapidly through large- and small-scale changes. Over evolutionary time-scales, centromeres migrate to non-centromeric regions and, in plants, heterochromatic knobs can acquire centromere activity. Discerning the functional significance of these changes will require comparative analyses of closely related species. Combined with functional assays, continued efforts in plant genomics will uncover key DNA elements that allow centromeres to retain their role in chromosome segregation while allowing rapid evolution.

The rapidly evolving field of plant centromeres

Centrosome biogenesis and function: centrosomics brings new understanding

 

Bettencourt-Dias M, Glover DM. Centrosome biogenesis and function: centrosomics brings new understanding. Nat Rev Mol Cell Biol. 2007 Jun; 8 (6): 451-63.

 

Centrosomes, which were first described in the late 19th century, are found in most animal cells and undergo duplication once every cell cycle so that their number remains stable, like the genetic material of a cell. However, their function and regulation have remained elusive and controversial. Only recently has some understanding of these fundamental aspects of centrosome function and biogenesis been gained through the concerted application of genomics and proteomics, which we term 'centrosomics'. The identification of new molecules has highlighted the evolutionary conservation of centrosome function and provided a conceptual framework for understanding centrosome behaviour and how it can go awry in human disease.

Centrosome biogenesis and function-centrosomics brings new understanding

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