Serial dilutions were plated on GC agar with and without spectinomycin (to a final concentration of 50 mg/l) and incubated overnight. The spectinomycin OFF to ON switching rate was determined by dividing the number of colonies on GC plates containing spectinomycin by the number check details of colonies on plain GC plates. Phase variation experiments were repeated at least 5 times for each strain. Significance in differences in phase variation frequency was calculated by the Kruskal-Wallis test. Results

and discussion Fpg is nearly ubiquitous among bacterial species and is highly conserved both within annotated neisserial genome sequences and clinical Mc isolates [10], as well as between evolutionarily distant prokaryotes. We examined the activity and specifiCity of recombinant Mc Fpg purified to homogeneity towards representative substrates resulting from oxidative DNA damage, 8oxoG and faPy, and detected prototype Fpg glycosylase activity. Previously, we have shown a synergistic effect between the two GO components MutY and Fpg in Mc [9]. Together, these findings emphasize a distinct role for Fpg in the defense against the deleterious effects

of reactive oxygen species. The putative Mc fpg open reading frame (ORF) consists of 828 bp SCH727965 mw and contains a DNA uptake sequence (DUS) (5′-GCCGTCTGAA-3′) (Figure 1A). The Mc genome harbours approximately 2000 copies of this highly conserved 10 bp sequence, which is required for efficient transformation [23]. A 12-mer DUS with two P505-15 order additional bp upstream of the core 10 bp repeat element improves the transformation efficiency [24]. The Mc fpg gene contains one 11-mer. A single

complete DUS or AT-DUS (10-, 11- or 12-mer) may promote the reacquisition of a gene by transformation if it is damaged or deleted and DUS occurs at higher densities in genome maintenance genes than in other house-keeping genes [25]. Figure 1 N. meningitidis (Mc) Fpg. (A) Physical map of the Mc fpg open reading frame and flanking regions. The fpg gene Sorafenib purchase contains a DNA uptake sequence (DUS). Primers KT1b and KT2b employed in cloning of the Mc fpg gene are depicted. The gene organization of the Mc fpg flanking regions is identical in all available neisserial genomes. NMB1296 encodes a hypothetical protein with sequence homology to DNA methyltransferases. A promoter is predicted upstream of NMB1296 (black arrow). The fpg and the lysophophatidic acid acyltransferase nlaA genes are putatively co-transcribed [27], although an inverted repeat (containing DUS) associated with transcription termination or attenutation is found downstream of the fpg gene. NMB1297 is COG-annotated mltD (membrane-bound lytic murein transglycosylase). NMB1293 is a hypothetical protein. The distribution of DUS and degenerate DUS is indicated. (B) Structural modeling of Mc Fpg based on E.