CODING SEQUENCE COMPOSITION FLANKING EITHER SIGNAL ELEMENT ALTERS V(D)J RECOMBINATION EFFICIENCY

Lymphoid V(D)J rearrangement is targeted by recombination signal seque nces (RSS) bordering V, D or J exons, We demonstrate that the DNA comp osition of flanking coding positions, particularly poly(A) or poly(T) stretches at one or both RSS, diminishes V(D)J recombination up to 100 -fold, Positionally correct cleavages occur in the inhibited reactions , since the junctions formed show the same frequency of precision as u ninhibited reactions, Open/shut cleavage/rejoining is not increased at a normal RSS in substrates containing inhibitory A/T homopolymers ver sus random sequence at a second RSS, Thus recombinase action at both c leavage sites is severely disrupted by modified coding sequences.