coli. This study Isolation of DNA Chromosomal DNA for PCR reactions was prepared from bacterial cultures by resuspending a small amount of cells in 5:l 1 M NaOH. The solution was neutralized by adding 5:l of 0.5 M Tris-HCl (pH 7.5). The suspension was further diluted in 90:l of purified water, and 1:l of this solution was used as a

template for PCR. Plasmid DNA isolations were carried out according to the alkaline lysis procedure [26]. PCR Polymerase chain reactions (PCR) were performed using various enzyme systems, based either on Taq or Pfu polymerases using chromosomal or plasmid DNA as a template. The primers used for various PCR reactions are described in Table 3. Amplification conditions were generally find more 41 cycles, using an annealing temperature 5°C lower than the Tm for the primer and extension times of 1-5 min. All PCR products were analyzed by agarose gel electrophoresis.

Table 3 Primers used in these studies Primer Name Primer Sequence NP1 AAAGGATCCCATGAACGCGGATTGCAGACG NP2 GGGGGATCCAGAAGATACCATACGCCTCT S1 GAGATGGGTAAAATCCGGGT S2 CGAACCGGATGCCGTAGAA learn more dwnstrm-F AAAATGTACAATTTGCCGGGCGGCAGCCTGC dwnstrm-R AAAATGTACAGGCGTTATCTCGCTCCCGGCG Omega-ABC TCAGATGGCGCGCCTGTACATCGATGGTGATTGATTGACGAAGCTTTATGC NfsB-BsmI-3F GTTTAGGGCGCATTCAAGAACCGCAAATCGTGCCGGC NfsB-BsmI-2R GCGGTTCTTGAATGCGGATAGAACCTGCTCTTTGCTTAA DNA sequence analysis DNA sequencing was performed by Macrogen, Inc. (Seoul, Kr.) or the DNA sequencing facility at the Center for Biosystems research at the University of Maryland. All nfsB sequences were obtained using Primers S1 and S2. Molecular check details biology procedures All procedures were performed using methods described in Sambrook et al. [27]. When biological reagents were used, they were used under the conditions described by their manufacturer. Restriction enzymes, T4 DNA ligase, polynucleotide kinase and appropriate buffers were obtained Adenosine triphosphate from New England Biolabs (Beverly, MA). S1 nuclease was obtained from Promega (Madison, WI). DNA samples were analyzed on agarose gels (0.8-1.0%) in TBE buffer

[27]. Genetic procedures Transformation-competent E. coli cells (strain DH5α-mcr) were prepared using the procedure of Inuoe [28], and stored at -80°C. To prepare cells for transformation, cells were thawed on ice, DNA added and the mixture incubated on ice for 10 min. The bacteria were heat-shocked at 37°C for 2 min., the total volume in the tube was increased to 1 ml by adding LB broth and the transformation mixture incubated at 37°C for 30 min. to 1 hr. to allow the bacteria to recover and begin expressing antibiotic-resistance proteins. Transformed bacteria were plated onto LB agar plates containing appropriate antibiotics and, if necessary, X-gal. For transformation of N. gonorrhoeae, piliated bacteria were resuspended to light turbidity in 1 ml GCK+ 10 mM MgCl2 + Kellogg’s supplement + 0.42% NaHCO3.