FIG. 1.

Genes present in the SR-11 Fad⁻ 4.5-kb PstI DNA fragment that contains the chloramphenicol resistance gene (cam). Heavy lines below the genes denote regions in the fragment that were sequenced. Sequencing reactions were performed with the BigDye Terminator Cycle Sequencing Kit, and reactions were analyzed on the ABI PRISM 310 (PE Applied Biosystems, Forest City, Calif.). Nucleotide sequences were analyzed using Clone Manager and Align Plus 3 programs (Sci-Ed Software, Durham, N.C.). Arrows above the genes denote the direction of transcription. Arrows below the genes denote the positions of the forward and reverse primers used for PCR amplification of the wild-type and defective cra genes. P, PstI.