The representation of a DNA sequence is the first stage of genome analysis. A wide variety of approaches has been proposed for different applications in bioinformatics. In this letter, based on the principle of symbolic dynamics, a novel representation approach is proposed, which maps DNA sequence into 3-D chaotic sequences of sawtooth function and completely conserve its biological information. With the application of the new representation approach to DNA sequence, three extended Kalman filters are used to implement gene prediction. Simulation results are presented to illustrate the validity and feasibility of the proposed representation approach to DNA sequence.