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Characterization, expression and subcellular distribution of a novel MFP1 (matrix attachment region-binding filament-like protein 1) in onion.

Authors
  • Samaniego, R1
  • de la Torre, C
  • Moreno Díaz de la Espina, S
  • 1 Nuclear Matrix Laboratory, Centro Investigaciones Biológicas, Consejo Superior de Investigaciones Cientificas, Madrid.
Type
Published Article
Journal
Protoplasma
Publication Date
Jan 01, 2008
Volume
233
Issue
1-2
Pages
31–38
Identifiers
DOI: 10.1007/s00709-008-0308-9
PMID: 18709475
Source
Medline
License
Unknown

Abstract

MFP1 (matrix attachment region-binding filament-like protein 1) is a conserved nuclear and chloroplast DNA-binding protein encoded by a nuclear gene, well characterized in dicot species. In monocots, only a 90 kDa MFP1-related protein had been characterized in the nucleus and nuclear matrix of Allium cepa proliferating cells. We report here a novel MFP1-related nuclear protein of 80 kDa in A. cepa roots, with M(r) and pI values similar to those of MFP1 proteins in dicot species, and which also displays a dual location, in the nucleus and chloroplasts of leaf cells. However, this novel protein is not a nuclear matrix component. It shows a spotted intranuclear distribution in small foci differing from the nuclear bodies containing the 90 kDa protein. In electron microscopy analysis, the intranuclear foci containing the 80 kDa MFP1 appeared as small loose structures at the periphery of condensed chromatin patches. This protein was also located in the nucleolus. It was abundant in meristematic cells, but its level fell when proliferation stopped. This different expression and distribution, and its preferential location at the boundaries between heterochromatin and euchromatin, suggest that the novel 80 kDa protein might be associated with decondensed DNA and could play a role in chromatin organization.

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