Mutations introduced into the H. pylori SsrA molecule. The model of the H. pylori mature SsrA molecule is after the tm RNA website http://www.indiana.edu/~tmrna/. As described in , the SsrAwobble, SsrASmpB, SsrAresumemutations that abolish the trans- translation process are boxed in red. Mutations of the mRNA-like domain that affect the tag are also indicated. The amino acid sequence of the tag (wild type or mutant) appended to trans-translated proteins are listed in the table.