Comparison of the Dna2 amino acid sequences from different species and the position of ScDna2 point mutations. The most conserved parts of the Dna2 proteins from S.cerevisiae, S.pombe, human, C.elegans and A.thaliana are shown as striped regions. The amino acid residue numbers of S.cerevisiae Dna2 are indicated. The amino acid sequences of the nuclease region are aligned in the lower portions of the figure. The alignment was created by the GeneDoc program. Most conserved sequences are shown dark shadowed and the less conserved sequences are shown gray shadowed. The amino acid point mutations made in Dna2 in this study are indicated as: 1, dna2-23 (D505N); 2, dna2-15 (R521K) dna2-26 (R521E); 3, dna2-24 (H547A); 4, dna2-21 (Q551E); 5, dna2-25 (DIEE640NIQQ); 6, dna2-27 (D657A); 7, dna2-22 (K689A); 8, dna2-28 (R735A). The thick line denotes the RecB homology region (19).