FIG. 1.

Predicted sequence of the D5 protein and identification of conserved domains and sites affected in temperature-sensitive and site-directed mutants. The predicted amino acid sequence of the vaccinia virus D5 protein (Western Reserve strain; protein database entry P04305) is shown. The residues altered in the various tsD5 strains are circled; those shown in gray circles have been previously mapped (T₁₄₃I in Cts24, S₁₆₁F in Cts17, and P₆₈₂S in Ets69) (11). The residues shown in white type within black circles indicate lesions that were mapped in this study: M₁₁₆I in Dts12, V₂₁₂A in Dts56, and S₁₆₁F and A₂₈₃T in Dts6389. The four conserved motifs identifying D5 as a member of the SFIII helicase subgroup of the AAA+ family of proteins (17) are boxed. These motifs include a Walker A box/P-loop (white box, black type), a Walker B box (light gray box, black type), the motif C of SFIII proteins (dark gray box, white italic type), and the AAA+ family motif (black box, white type). The invariant residues targeted for site-directed mutagenesis within these motifs are underlined (K₅₀₉A, E₅₅₇Q, N₆₀₅D, and R₆₁₉A,R₆₂₀A). The inverted triangles mark the beginning of the 301-D5 (filled) or 413-D5 (empty) fragment. While the majority of the ts lesions map to the N-terminal portion of the protein, the C-terminal portion of D5 contains the putative enzymatic/functional domains.