HMGB1 is an architectural protein in chromatin, acting also as a signaling molecule outside the cell. Recent reports from several laboratories provided evidence that a number of both the intracellular and extracellular functions of HMGB1 may depend on redox-sensitive cysteine residues of the protein. In this study we demonstrate that redox state of HMGB1 can significantly modulate the ability of the protein to bind and bend DNA, as well as to promote DNA end-joining. We also report a high affinity binding of histone H1 to hemicatenated DNA loops and DNA minicircles. Finally, we show that reduced HMGB1 can readily displace histone H1 from DNA, while oxidized HMGB1 has limited capacity for H1 displacement. Our results suggested a novel mechanism for the HMGB1-mediated modulation of histone H1 binding to DNA. Possible biological consequences of linker histones H1 replacement by HMGB1 for the functioning of chromatin are discussed.

• MeSH
• chromatin genetika   metabolismus   MeSH
• exprese genu MeSH
• genetické vektory chemie   MeSH
• histony genetika   metabolismus   MeSH
• konkatenovaná DNA genetika   metabolismus   MeSH
• kruhová DNA genetika   metabolismus   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• oxidace-redukce MeSH
• protein HMGB1 genetika   metabolismus   MeSH
• rekombinantní proteiny genetika   metabolismus   MeSH
• skot MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chromatin MeSH
• histony MeSH
• konkatenovaná DNA MeSH
• kruhová DNA MeSH
• protein HMGB1 MeSH
• rekombinantní proteiny MeSH

DNA topoisomerase IIalpha (topo IIalpha) is an essential nuclear enzyme and its unique decatenation activity has been implicated in many aspects of chromosome dynamics such as chromosome replication and segregation during mitosis. Here we show that chromatin-associated protein HMGB1 (a member of the large family of HMG-box proteins with possible functions in DNA replication, transcription, recombination and DNA repair) promotes topo IIalpha-mediated catenation of circular DNA, relaxation of negatively supercoiled DNA and decatenation of kinetoplast DNA. HMGB1 interacts with topo IIalpha and this interaction, like the stimulation of the catalytic activity of the enzyme, requires both HMG-box domains of HMGB1. A mutant of HMGB1, which cannot change DNA topology stimulates DNA decatenation by topo IIalpha indistinguishably from the wild-type protein. Although HMGB1 stimulates ATP hydrolysis by topo IIalpha, the DNA cleavage is much more enhanced. The observed abilities of HMGB1 to interact with topo IIalpha and promote topo IIalpha binding to DNA suggest a mechanism by which HMGB1 stimulates the catalytic activity of the enzyme via enhancement of DNA cleavage.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• antigeny nádorové metabolismus   MeSH
• diketopiperaziny MeSH
• DNA vazebné proteiny metabolismus   MeSH
• DNA-topoisomerasy typu II metabolismus   MeSH
• DNA chemie   metabolismus   ultrastruktura   MeSH
• elektroforéza v agarovém gelu MeSH
• inhibitory enzymů farmakologie   MeSH
• katalýza MeSH
• kinetoplastová DNA metabolismus   MeSH
• konformace nukleové kyseliny MeSH
• kruhová DNA metabolismus   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• piperaziny farmakologie   MeSH
• protein HMGB1 MeSH
• proteiny s vysokou pohyblivostí metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• superhelikální DNA metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione MeSH Prohlížeč
• adenosintrifosfát MeSH
• antigeny nádorové MeSH
• diketopiperaziny MeSH
• DNA vazebné proteiny MeSH
• DNA-topoisomerasy typu II MeSH
• DNA MeSH
• Hbp1 protein, rat MeSH Prohlížeč
• inhibitory enzymů MeSH
• kinetoplastová DNA MeSH
• kruhová DNA MeSH
• piperaziny MeSH
• protein HMGB1 MeSH
• proteiny s vysokou pohyblivostí MeSH
• represorové proteiny MeSH
• superhelikální DNA MeSH

We showed previously that bacterially expressed full-length human wild-type p53b(1-393) binds selectively to supercoiled (sc)DNA in sc/linear DNA competition experiments, a process we termed supercoil-selective (SCS) binding. Using p53 deletion mutants and pBluescript scDNA (lacking the p53 recognition sequence) at native superhelix density we demonstrate here that the p53 C-terminal domain (amino acids 347-382) and a p53 oligomeric state are important for SCS binding. Monomeric p53(361-393) protein (lacking the p53 tetramerization domain, amino acids 325-356) did not exhibit SCS binding while both dimeric mutant p53(319- 393)L344A and fusion protein GCN4-p53(347-393) were effective in SCS binding. Supershifting of p53(320-393)-scDNA complexes with monoclonal antibodies revealed that the amino acid region 375-378, constituting the epitope of the Bp53-10.1 antibody, plays a role in binding of the p53(320-393) protein to scDNA. Using electron microscopy we observed p53-scDNA nucleoprotein filaments produced by all the C-terminal proteins that displayed SCS binding in the gel electrophoresis experiments; no filaments formed with the monomeric p53(361- 393) protein. We propose a model according to which two DNA duplexes are compacted into p53-scDNA filaments and discuss a role for filament formation in recombination.

• MeSH
• biologické modely MeSH
• lidé MeSH
• makromolekulární látky MeSH
• molekulární sekvence - údaje MeSH
• nádorový supresorový protein p53 chemie   metabolismus   ultrastruktura   MeSH
• rekombinantní fúzní proteiny metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční delece MeSH
• superhelikální DNA metabolismus   ultrastruktura   MeSH
• terciární struktura proteinů MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• makromolekulární látky MeSH
• nádorový supresorový protein p53 MeSH
• rekombinantní fúzní proteiny MeSH
• superhelikální DNA MeSH