FIG 1.

Mutational strategy to examine the role of a polythymine [poly(T)] tract in the in vivo expression of sabA in H. pylori strain J99. (a) Plasmid constructs containing the jhp0662-sabA region were marked for allelic replacement in H. pylori J99 by the addition of the chloramphenicol resistance gene into the MluI site in jhp0662 and moved into H. pylori J99 to create the control mutant possessing a wild-type poly(T) tract length (T = 18). (b to f) All subsequent mutations were created using the control mutant plasmid. Numbers are nucleotide positions relative to the transcriptional start point (16), shown as a bent arrow. The number of tandem thymines is indicated in each mutant, and added nucleotides are indicated by gray and underlining.