Clarification of the mechanism involved in chromosomal translocations founded in hematologic neoplasms.

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Translin has been identified as a DNA binding protein that specifically recognizes the consensus sequences motifs, ATGCAG and GCCC[A/T][G/C][G/C][A/T], at breakpoint junctions in many chromosomal translocations in human lymphoid neoplasms involving 1p32, 3q27, 5q31, 8q24, 9q34, 9q34.3, 10q24, 11p13, 11q13, 14q11, 14q32, 14q32.1, 17q22, 18q21, 19p13, and 22q11. 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 1eu184 and leu191 in the leucine zipper motif of human Translin resulted in loss of the multimeric structure and abrogation of DNA binding. Point mutations at R86, H88, H90 to T86, N88, N90 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.