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The genes encoding Arabidopsis ORC subunits are E2F targets and the two ORC1 genes are differently expressed in proliferating and endoreplicating cells.

ABSTRACT: Initiation of eukaryotic DNA replication depends on the function of pre-replication complexes (pre-RC), one of its key component being the six subunits origin recognition complex (ORC). In spite of a significant degree of conservation among ORC proteins from different eukaryotic sources, the regulation of their availability varies considerably in different model systems and cell types. Here, we show that the six ORC genes of Arabidopsis thaliana are regulated at the transcriptional level during cell cycle and development. We found that Arabidopsis ORC genes, except AtORC5, contain binding sites for the E2F family of transcription factors. Expression of AtORC genes containing E2F binding sites peaks at the G1/S-phase. Analysis of AtORC gene expression in plants with reduced E2F activity, obtained by expressing a dominant negative version of DP, the E2F heterodimerization partner, and with increased E2F activity, obtained by inactivation of the retinoblastoma protein, led us to conclude that all AtORC genes, except AtORC5 are E2F targets. Interestingly, Arabidopsis contains two AtORC1 (a and b) genes, highly conserved at the amino acid level but with unrelated promoter sequences. AtORC1b expression is restricted to proliferating cells. However, AtORC1a is preferentially expressed in endoreplicating cells based on our analysis in endoreplicating tissues and in a mutant with altered endocycle pattern. This suggests a differential expression of the two ORC1 genes in Arabidopsis.

SUBMITTER: Diaz-Trivino S

PROVIDER: S-EPMC1236721 | biostudies-literature | 2005

REPOSITORIES: biostudies-literature

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The genes encoding Arabidopsis ORC subunits are E2F targets and the two ORC1 genes are differently expressed in proliferating and endoreplicating cells.

Diaz-Trivino Sara S del Mar Castellano María M de la Paz Sanchez María M Ramirez-Parra Elena E Desvoyes Bénédicte B Gutierrez Crisanto C

Nucleic acids research 20050922 17

Initiation of eukaryotic DNA replication depends on the function of pre-replication complexes (pre-RC), one of its key component being the six subunits origin recognition complex (ORC). In spite of a significant degree of conservation among ORC proteins from different eukaryotic sources, the regulation of their availability varies considerably in different model systems and cell types. Here, we show that the six ORC genes of Arabidopsis thaliana are regulated at the transcriptional level during ...[more]

PMID: 16179646

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Project description:BackgroundMany studies have proven the importance of SnRK1 in the regulation of carbohydrate metabolism and plant development. Compared to Arabidopsis, much less is known about SnRK1 complexes in crop plants, and therefore, more work needs to be done to identify SnRK1 genes and to investigate their function in crop plants.MethodsIn this study we identified five SnRK1-related genes in potato by analyzing the potato genome through BLAST, which encode one α-subunit isoform (stKIN), two β-subunit isoforms (stKINβ1 and stKINβ2) and two γ-subunit isoforms (stKINγ and stKINβγ). To investigate the functions of SnRK1 in the tuber development of potato, we further made overexpression and RNAi transgenic plants of these five genes. Based on these overexpression transgenic plants, the Fast protein liquid chromatography (FPLC) were employed to purify SnRK1 complexes, which were tracked by western-blot.ResultsExperiments in vivo and in vitro showed that these five proteins in potato are functional SNF1/AMPK/SnRK1-related proteins. The SnRK1 activity decreased by 60% in the RNAi transgenic lines of stKIN; the starch content increased by 25% in the overexpression transgenic lines of stKIN, compared to that in the wild-type lines, whereas there is no significant difference in SnRK1 activity and starch content in the RNAi transgenic or overexpression lines of stKINβ1, stKINβ2, stKINγ and stKINβγ. In addition, we found that a few different SnRK1 complexes are present in potato by partially purifying SnRK1 complexes from these overexpression transgenic plants.ConclusionsFive functional SnRK1-related genes were identified in potato, including three novel genes, which encode one α-subunit isoform (stKIN), two β-subunit isoforms (stKINβ1 and stKINβ2) and two γ-subunit isoforms (stKINγ and stKINβγ). We found that a few SnRK1 related genes are present in potato tuber, which form several different SnRK1 isoenzymes. We found that stKIN is the primary α subunit of SnRK1 in potato tuber and plays important roles in the development of potato tubers.

Dataset Information

The genes encoding Arabidopsis ORC subunits are E2F targets and the two ORC1 genes are differently expressed in proliferating and endoreplicating cells.

Publications

The genes encoding Arabidopsis ORC subunits are E2F targets and the two ORC1 genes are differently expressed in proliferating and endoreplicating cells.

Similar Datasets

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