FIG. 3.

Amino acid sequences of the RelA/SpoT-like proteins, which are identical in the opaque-plaque variants of both the R. rickettsii R and the R. rickettsii Iowa strains. The position of the mutation in the clear-plaque variant of the R. rickettsii R strain (H118Y) is shown below, as is the position of the mutation in the clear-plaque variant of the R. rickettsii Iowa strain (W77*). Conserved amino acids shared with the active site of the synthetase domain of the Streptococcus equisimilis Rel protein (16) are identified with asterisks.