FIG. 2.

Nucleotide sequence of the 1,846-bp NruI fragment of plasmid pJP4 containing the tfdK gene. DNA sequencing of subclones of this fragment was performed in a Thermosequenase reaction (Amersham, Little Chalfont, United Kingdom) with IRD-41-labeled primers (MWG Biotech, Ebersberg, Germany). DNA fragments were separated and analyzed on a LiCOR Automated Sequencer (model 400L; LiCOR, Lincoln, Nebr.). Relevant restriction sites are indicated in italics. A putative ribosome binding site is boxed. ISJP4 DNA is underlined, and its border is indicated by a black arrow (IR-R). The translation product of tfdK is given below the nucleotide sequence. Two characteristic MFS motifs are circled (13); underlined within these are conserved amino acid residues. Arrows on the amino acid sequence indicate predicted transmembrane α-helices (see text); arrows that point in the same direction as the tfdK reading frame represent helices with an inside-to-outside orientation, oppositely pointed arrows represent outside-to-inside membrane helices. Eleven such helices were identified by the TMpred program of the ISREC Bioinformatics Group (Epalinges, Switzerland). The position of a 12th hydrophobic α-helix is also shown (open arrow), but this helix was not recognized by the program as a membrane-spanning one.