The DNA binding activity of Translin is mediated by a basic region in the ring-shaped structure conserved in evolution

DNA binding proteins, for the most part, function as dimers or tetramers which recognize their target sequences. Here we show that Translin, a novel single-stranded DNA end binding protein, forms a ring-shaped structure conserved throughout evolution and that this structure is responsible for its DNA binding activity. Point mutations at Leu(184) and Leu(191) in the leucine zipper motif of human Translin resulted in loss of the multimeric structure and abrogation of DNA binding. Point mutations at R-86, H-88, H-90 to T-86, N-88, N-90 in one of the basic regions, however, completely inhibited the DNA binding activity without affecting the multimeric structure. These results support the view that the DNA binding domain of Translin is formed in the ring-shaped structure in combination with its basic region (amino acids 86-97) polypeptides. (C) 1999 Federation of European Biochemical Societies.