Genome based identification and analysis of the pre‐replicative complex of Arabidopsis thaliana

Abstract

Eukaryotic DNA replication requires an ordered and regulated machinery to control G1/S transition. The formation of the pre-replicative complex (pre-RC) is a key step involved in licensing DNA for replication. Here, we identify all putative components of the full pre-RC in the genome of the model plant Arabidopsis thaliana. Different from the other eukaryotes, Arabidopsis houses in its genome two putative homologs of ORC1, CDC6 and CDT1. Two mRNA variants of AtORC4 subunit, with different temporal expression patterns, were also identified. Two-hybrid binary interaction assays suggest a primary architectural organization of the Arabidopsis ORC, in which AtORC3 plays a central role in maintaining the complex associations. Expression profiles differ among pre-RC components suggesting the existence of various forms of the complex, possibly playing different roles during development. In addition, the expression of the putative pre-RC genes in non-proliferating plant tissues suggests that they might have roles in processes other than DNA replication licensing.

Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode

“…In order to investigate whether a particular phase of the cell cycle or cellular process associated with it was affected in our experiments, we searched our data set for (1) the expression of 39 M-phase genes identified by Pauwels et al (2008; cluster 5 therein) and described as being down-regulated by MeJA; (2) 76 genes associated with the DNA synthesis phase (S phase) and encoding prereplication complex (pre-RC) components selected primarily from previous studies (Masuda et al, 2004;Menges et al, 2005); as well as (3) histones (http://chromdb.org/; López-Juez et al, 2008). Our analysis shows, in agreement with previous studies, that many core cell cycle regulators such as cyclins are expressed at higher levels early during leaf development and that transcript levels decrease at later time points; however, the expression of the majority of these genes was not affected by MeJA (Supplemental Table S5).…”

Arabidopsis ORC1 is a PHD-containing H3K4me3 effector that regulates transcription

“…Both Arabidopsis ORC1a and ORC1b proteins, but not yeast and animal ORC1, contain two tandem Zn 2ϩ fingers (Fig. 1A), whose predicted secondary structure constitutes a PHD motif (19,21). According to 3D modeling, this region fits in the PHD fold of human CHD4 (Fig.…”

“…Arabidopsis contains two ORC1 genes (ORC1a and ORC1b) that encode proteins possessing Ϸ92% amino acid similarity over the entire protein (19,20). Here, we have uncovered a novel role of Arabidopsis ORC1 in transcriptional regulation as a H3K4me3 effector protein.…”

Genomic Analysis of the DNA Replication Timing Program during Mitotic S Phase in Maize (Zea mays) Root Tips

“…These studies were largely based on cell cycle kinetics and DNA fiber autoradiography experiments primarily using root tip meristem cells from various plant species ( Van't Hof, 1976; Van't Hof et al, 1978a, 1978bVan't Hof and Bjerknes, 1981;Kidd et al, 1987). More recently, studies also characterized plant homologs of proteins involved in the prereplicative complex (Kimura et al, 2000;Castellano et al, 2001;Ramos et al, 2001;Witmer et al, 2003;Masuda et al, 2004;Mori et al, 2005;Shultz et al, 2007). However, genomic analyses of DNA replication and replication origins in plants have been sparse and thus far have focused exclusively on Arabidopsis.…”