Four differently chromatin‐associated maize HMG domain proteins modulate DNA structure and act as architectural elements in nucleoprotein complexes

Abstract

SummaryIn contrast to other eukaryotes which usually express two closely related HMG1-like proteins, plant cells have multiple relatively variable proteins of this type. A systematic analysis of the DNA-binding properties of four chromosomal HMG domain proteins from maize revealed that they bind linear DNA with similar affinity. HMGa, HMGc1/2 and HMGd specifically recognise diverse DNA structures such as DNA mini-circles and supercoiled DNA. They induce DNA-bending, and constrain negative superhelical turns in DNA. In the presence of DNA, the HMG domain proteins can self-associate, whereas they are monomeric in solution. The maize HMG1-like proteins have the ability to facilitate the formation of nucleoprotein structures to different extents, since they can efficiently replace a bacterial chromatin-associated protein required for the site-specific β-mediated recombination. A variable function of the HMG1-like proteins is indicated by their differential association with maize chromatin, as judged by their 'extractability' from chromatin with spermine and ethidium bromide. Collectively, these findings suggest that the various plant chromosomal HMG domain proteins could be adapted to act in different nucleoprotein structures in vivo.

Protein Kinase CK2 Differentially Phosphorylates Maize Chromosomal High Mobility Group B (HMGB) Proteins Modulating Their Stability and DNA Interactions

“…Moreover, the plant HMGB proteins are structurally more variable than mammalian, insect, and yeast HMGB proteins, both in size and in primary structure (6). They display different expression levels in the plant, are differently associated with chromatin, and exhibit differences in some of their DNA interactions (7)(8)(9). Therefore, the different plant HMGB proteins might have been adapted to act as accessory factors in a variety of specific nucleoprotein structures (6).…”

“…Although the amino acid sequences of the HMG-box domains of the various plant HMGB proteins are relatively conserved, the basic and acidic flanking regions are variable in length and sequence (6). The plant HMGB proteins differ in their chromatin association and nucleosome binding (7), in their expression in the plant (8), and in some of their DNA interactions (9). Therefore, they may be adapted to act in different DNA-dependent processes in the nucleus.…”

Generation of Food-Grade Recombinant Lactic Acid Bacterium Strains by Site-Specific Recombination

“…Since an accessory factor needed for ␤-mediated recombination is provided by eukaryotic and prokaryotic cells (28,29), we expected that an L. casei-encoded chromatin-associated protein was present and would assist ␤-mediated site-specific recombination. This is consistent with the fact that the ␤-recombinase catalyzes in vivo deletions in mouse, E. coli, and B. subtilis cells (2,8).…”

Validation of a Self-Excising Marker in the Human Pathogen Aspergillus fumigatus by Employing the β-Rec/ six Site-Specific Recombination System

“…Incompatible restriction sites (SfiI-1 and SfiI-2) assist in the assembly of gene replacement cassettes. (1,34,41). The successful recombination in A. fumigatus demonstrates that this fungal host apparently provides for such a host factor assisting in ␤ recombination, and it can be speculated that other aspergilli or even fungal species in general are capable of supporting this recombination system.…”