MFP1, a Novel Plant Filament-Like Protein with Affinity for Matrix Attachment Region DNA

Meier, Iris; Phelan, Thomas; Gruissem, Wilhelm; Spiker, Steven; Schneider, Dagmar

doi:10.2307/3870416

Cited by 27 publications

(83 citation statements)

References 30 publications

(42 reference statements)

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“…Previous results have shown that MFP1 is present in a nuclear matrix preparation derived from tobacco NT-1 suspension-cultured cells (Meier et al, 1996). However, we noticed that the fraction of total MFP1 detectable in the nuclear matrix varied from experiment to experiment (data not shown).…”

Section: A Variable Amount Of Mfp1 Is Tightly Associated With the Nuccontrasting

confidence: 51%

“…Whereas the majority of MFP1 is highly ␣ helical and predicted to form a coiled-coil structure (Meier et al, 1996), the first 150 amino acids lack a coiled-coil structure but contain two hydrophobic domains (indicated as red bars in Figures 3 and 5). The first hydrophobic domain is similar to transmembrane domains from a variety of membrane attached proteins (Meier et al, 1996), indicating that the N terminus of MFP1 might act as a membrane-attachment domain. To test whether the hydrophobic domains are involved in the targeting of MFP1 to the speckles, we constructed two N-terminal deletion mutants of MFP1-mGFP ( Figure 5A).…”

Section: The Hydrophobic N Terminus Of Mfp1 Is Required For Its Corrementioning

confidence: 99%

“…This domain contains two stretches of hydrophobic amino acids, between positions 61 and 73 and between positions 103 and 124. Both hydrophobic sequences are predicted to be transmembrane domains (von Heijne, 1992;Meier et al, 1996), and their sequence and spacing is highly conserved between MFP1 sequences from tomato, tobacco, and Arabidopsis (P. Harder and I. Meier, unpublished results).One possible function for the N-terminal domain is that of a signal peptide for cotranslational ER import. Results of the SignalP signal peptide prediction program (Nielsen et al, 1997) are ambiguous for MFP1 and are more supportive of the N terminus being a signal anchor sequence (uncleaved signal peptide) than a real signal peptide.…”

mentioning

confidence: 99%

“…Thus far, no information exists about transmembrane domains involved in the specific sorting of proteins to the nuclear envelope. Although the first hydrophobic domain of MFP1 has convincing sequence similarity to a number of transmembrane domains (Meier et al, 1996), its length of 13 amino acids appears to be too short for a canonical ␣ -helical transmembrane domain. Hence, it is tempting to speculate that a specific composition of the lipid bilayers close to the nucleus might be involved in determining the localization of proteins with short hydrophobic domains, such as MFP1.…”

mentioning

confidence: 99%

“…A small number of MAR binding proteins have been purified and cloned from animals, and they subsequently have been shown to be localized in the nuclear matrix (von Kries et al, 1991;Dickinson et al, 1992;Renz and Fackelmayer, 1996;Göhring et al, 1997). Thus far, a single MAR binding protein has been identified from plants (Meier et al, 1996). In contrast to the animal proteins, the plant protein MFP1 (for MAR binding filament-like protein 1) has a filament protein-like structure that makes it a good candidate for a MAR binding constituent of the observed nuclear filaments.…”

mentioning

confidence: 99%

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Matrix Attachment Region Binding Protein MFP1 Is Localized in Discrete Domains at the Nuclear Envelope

Gindullis

Meier

1999

Plant Cell

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Recently, it has been suggested that nuclear processes, such as replication, transcription, and splicing, are spatially organized and associated with a nuclear framework called the nuclear matrix, a structure of unknown molecular composition. It has been shown that chromatin is attached to the nuclear matrix via specific DNA fragments called matrix attachment regions (MARs). We have begun to dissect the plant nuclear matrix by isolating a DNA binding protein with specific affinity for MARs. Here, it is shown that MAR binding filament-like protein 1 (MFP1) is associated with specklelike structures at the nuclear periphery that are part of isolated nuclei and the nuclear matrix. A predicted N-terminal transmembrane domain is necessary for the specific targeting of MFP1 to the speckles, indicating an association with the nuclear envelope-endoplasmic reticulum continuum. In addition, it is shown that a marker protein for plant microtubule organizing centers, which has been shown to be localized on the outside of the plant nuclear envelope, is also part of the nuclear matrix. These findings indicate a close and previously undescribed connection in plants between the nuclear envelope and the internal nuclear matrix, and they suggest a function for MFP1 in attaching chromatin to specific sites at the nuclear periphery. INTRODUCTIONThe nuclear matrix hypothesis proposes a structural framework for the eukaryotic nucleus that is similar to the cytoskeleton. Biochemically, the nuclear matrix is defined as the insoluble material that remains after extraction of nuclei with high-salt solutions (Berezney and Coffey, 1974) or with the chaotropic agent lithium diiodosalicylate (Mirkovitch et al., 1984) and treatment with DNases. Electron microscopy has shown a network of fibers of ‫ف‬ 10 nm in diameter. These fibers resemble the intermediate filaments of the cytoskeleton. Because they can be detected only under certain preparation conditions (He et al., 1990), their in vivo existence has been somewhat controversial.The isolated nuclear matrix binds specifically to certain DNA elements called matrix attachment regions (MARs). MARs are generally AT-rich DNA sequences that are several hundred base pairs long and are localized in the noncoding regions of the DNA, often flanking genes (Gasser and Laemmli, 1987). MARs have a positive effect on gene expression (Allen et al., 1993(Allen et al., , 1996Mlynárová et al., 1996) that is believed to be due to the establishment of independent and transcriptionally active chromatin domains between two MARs (Spiker and Thompson, 1996). Although the nuclear matrix was identified more than 20 years ago (Berezney and Coffey, 1974), none of its structural components has been isolated and molecularly characterized from any organism. One strategy to identify such components has been to isolate proteins that specifically bind to MARs. A small number of MAR binding proteins have been purified and cloned from animals, and they subsequently have been shown to be localized in the nuclear matrix (von Kri...

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Section: A Variable Amount Of Mfp1 Is Tightly Associated With the Nuccontrasting

confidence: 51%

Section: The Hydrophobic N Terminus Of Mfp1 Is Required For Its Corrementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Matrix Attachment Region Binding Protein MFP1 Is Localized in Discrete Domains at the Nuclear Envelope

Gindullis

Meier

1999

Plant Cell

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The plant nuclear envelope

Meier¹

2001

CMLS, Cell. Mol. Life Sci.

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This review summarizes our present knowledge about the composition and function of the plant nuclear envelope. Compared with animals or yeast, our molecular knowledge of the nuclear envelope in higher plants is in its infancy. However, there are fundamental differences between plants and animals in the structure and function of the nuclear envelope. This review will compare and contrast these differences for nuclear pore complexes, nuclear transport, inner nuclear envelope proteins and the role of the nuclear envelope during mitosis. In some cases, seemingly 'novel' aspects of plant nuclear envelope function may provide new insight into the animal cell nucleus.

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Phosphorylation by protein kinase CKII modulates the DNA-binding activity of a chloroplast nucleoid-associated protein

Jeong

Peffer

Meier

2004

Planta

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Plastid DNA, like bacterial and mitochondrial DNA, is organized into protein-DNA complexes called nucleoids. Plastid nucleoids are believed to be associated with the inner envelope in developing plastids and the thylakoid membranes in mature chloroplasts, but the mechanism for this localization is unknown. MFP1 is a DNA-binding, coiled-coil protein associated with the thylakoid membranes of mature chloroplasts. It is also a component of nucleoids, suggesting a function at the interface of the chloroplast genome and the photosynthetic membranes. Several thylakoid proteins are phosphorylated by a protein kinase CKII-like activity and the alpha subunit of a chloroplast-located CKII has recently been identified as a component of the chloroplast transcription complex. Here, we show evidence for the phosphorylation of MFP1 in purified chloroplasts from tobacco (Nicotiana tabacum L.). We demonstrate that the DNA-binding domain of MFP1 is a substrate for CKII and that phosphorylation by CKII inhibits DNA binding. Using site-directed mutagenesis, we identify a conserved twin CKII site in the DNA-binding domain that is required for the inhibition of DNA binding. Phosphorylation of MFP1 by chloroplast CKII as a possible means to modulate its DNA-binding activity is discussed.

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MFP1, a Novel Plant Filament-Like Protein with Affinity for Matrix Attachment Region DNA

Cited by 27 publications

References 30 publications

Matrix Attachment Region Binding Protein MFP1 Is Localized in Discrete Domains at the Nuclear Envelope

Matrix Attachment Region Binding Protein MFP1 Is Localized in Discrete Domains at the Nuclear Envelope

The plant nuclear envelope

Phosphorylation by protein kinase CKII modulates the DNA-binding activity of a chloroplast nucleoid-associated protein

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