Interaction of maize chromatin-associated HMG proteins with mononucleosomes: role of core and linker histones.
Two groups of plant chromatin-associated high mobility group (HMG) proteins, namely the HMGA family, typically containing four A/T-hook DNA-binding motifs, and the HMGB family, containing a single HMG-box DNA-binding domain, have been identified. We have examined the interaction of recombinant maize HMGA and five different HMGB proteins with mononucleosomes (containing approx. 165 bp of DNA) purified from micrococcal nuclease-digested maize chromatin. The HMGB proteins interacted with the nucleosomes independent of the presence of the linker histone H1, while the binding of HMGA in the presence of H1 differed from that observed in the absence of H1. HMGA and the HMGB proteins bound H1-containing nucleosome particles with similar affinity. The plant HMG proteins could also bind nucleosomes that were briefly treated with trypsin (removing the N-terminal domains of the core histones), suggesting that the histone N-termini are dispensable for HMG protein binding. In the presence of untreated nucleosomes and trypsinised nucleosomes, HMGB1 could be chemically crosslinked with a core histone, which indicates that the trypsin-resistant part of the histones within the nucleosome is the main interaction partner of HMGB1 rather than the histone N-termini. In conclusion, these results indicate that specific nucleosome binding of the plant HMGB proteins requires simultaneous DNA and histone contacts.
Lichota
Jacek
J
Institute of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
Grasser
Klaus D
KD
D047390:Casein Kinase II; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D024002:HMGB Proteins / Q000737:chemistry / Q000378:metabolism*; D006609:High Mobility Group Proteins / Q000737:chemistry / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D008836:Micrococcal Nuclease; D009707:Nucleosomes / Q000378:metabolism*; D010766:Phosphorylation; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D014357:Trypsin; D003313:Zea mays
D002843:Chromatin; D024002:HMGB Proteins; C106684:HMGa protein, Zea mays; D006609:High Mobility Group Proteins; D006657:Histones; D009707:Nucleosomes; D010940:Plant Proteins; D004247:DNA; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D008836:Micrococcal Nuclease; D014357:Trypsin