FIG. 1.

Primers used for wzz gene amplification and site-directed mutagenesis. Primers 466 and 465 were based on the wzz gene sequence of HU1124 (5), with the addition of EcoRI and BamHI sites at the 5′ end, respectively. All of the other primers were based on the wzz gene of E4991/76. Primer 854 contains a PstI site and was used to create a chimeric wzz gene from C258-94 and E4991/76. The primers used for site-directed mutagenesis were 704, in which a glycine residue is inserted between amino acid residues 220 and 221; 705, in which isoleucine replaces valine at residue 224; 881, in which isoleucine replaces methionine at residue 77; 882, in which serine replaces glutamine at residue 83; 883, in which glutamate replaces aspartate at residue 90; 945, in which glutamate and isoleucine replace aspartate and leucine at residues 90 and 91; and 988, in which isoleucine replaces leucine at residue 91. The base substitutions are in boldface, and the PstI site in primer 854 is indicated by boldface and italics.