RESUMO
The X-ray structure of the nuclear factor-kappaB (NF-kappaB) p52:RelB:kappaB DNA complex reveals a new recognition feature not previously seen in other NF-kappaB:kappaB DNA complexes. Arg 125 of RelB is in contact with an additional DNA base pair. Surprisingly, the p52:RelB R125A mutant heterodimer shows defects both in DNA binding and in transcriptional activity only to a subclass of kappaB sites. We found that the Arg 125-sensitive kappaB sites contain more contiguous and centrally located A:T base pairs than do the insensitive sites. A protein-induced kink observed in this complex, which used an AT-rich kappaB site, might allow the DNA contact by Arg 125; such a kink might not be possible in complexes with non-AT-rich kappaB sites. Furthermore, we show that the p52:RelB heterodimer binds to a broader spectrum of kappaB sites when compared with the p50:RelA heterodimer. We suggest that the p52:RelB heterodimer is more adaptable to complement sequence and structural variations in kappaB sites when compared with other NF-kappaB dimers.
Assuntos
DNA/química , Subunidade p52 de NF-kappa B/química , Fator de Transcrição RelB/química , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Composição de Bases , Cristalografia por Raios X , DNA/metabolismo , Dimerização , Humanos , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Mutação Puntual , Ligação Proteica , Mapeamento de Interação de Proteínas , Estrutura Terciária de Proteína , Alinhamento de Sequência , Relação Estrutura-Atividade , Especificidade por Substrato , Transcrição GênicaRESUMO
Several mutations and atypical splice variants of WISP3 (CCN6) have been linked to connective tissue disorders and different forms of malignancies. Functional studies have suggested that WISP3 contributes to tissue maintenance/homeostasis. The precise molecular mechanism of WISP3 function in different cell types, however, remains unresolved. The present study was conducted to investigate the potential impact of WISP3 on the accumulation of reactive oxygen species (ROS) and oxidative stress, which are central to cell/tissue maintenance. Our experimental results suggest that WISP3 regulates the accumulation of cellular ROS, and mutations in WISP3 or loss of expression of WISP3 compromise this function.
