Image_1_Phase-variable Type I methyltransferase M.NgoAV from Neisseria gonorrhoeae FA1090 regulates phasevarion expression and gonococcal phenotype.TIF

The restriction-modification (RM) systems are compared to a primitive, innate, prokaryotic immune system, controlling the invasion by foreign DNA, composed of methyltransferase (MTase) and restriction endonuclease. The biological significance of RM systems extends beyond their defensive function, but the data on the regulatory role of Type I MTases are limited. We have previously characterized molecularly a non-canonical Type I RM system, NgoAV, with phase-variable specificity, encoded by Neisseria gonorrhoeae FA1090. In the current work, we have investigated the impact of methyltransferase NgoAV (M.NgoAV) activity on gonococcal phenotype and on epigenetic control of gene expression. For this purpose, we have constructed and studied genetic variants (concerning activity and specificity) within M.NgoAV locus. Deletion of M.NgoAV or switch of its specificity had an impact on phenotype of N. gonorrhoeae. Biofilm formation and planktonic growth, the resistance to antibiotics, which target bacterial peptidoglycan or other antimicrobials, and invasion of human epithelial host cells were affected. The expression of genes was deregulated in gonococcal cells with knockout M.NgoAV gene and the variant with new specificity. For the first time, the existence of a phasevarion (phase-variable regulon), directed by phase-variable Type I MTase, is demonstrated.</p

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-8

<p><b>Copyright information:</b></p><p>Taken from "Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage"</p><p>http://www.biomedcentral.com/1471-2180/7/66</p><p>BMC Microbiology 2007;7():66-66.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1931599.</p><p></p>with Uranyl acetate and visualized on a Zeiss EM10CA electron microscope (160,000 magnification)

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-1

<p><b>Copyright information:</b></p><p>Taken from "Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage"</p><p>http://www.biomedcentral.com/1471-2180/7/66</p><p>BMC Microbiology 2007;7():66-66.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1931599.</p><p></p>arrows with vertical lines represent the CDSs encoding the repressors and other regulatory genes. The open arrows represent the CDSs with unknown function. Arrows with cross-hatching represent integrases. The filled rectangles (black or gray) represent putative non coding regions. The regions homologous for NgoΦ1, NgoΦ2 and NgoΦ3 are shown as rectangles with cross-hatched regions. The regions homologous for NgoΦ1 and NgoΦ2 are shown as solid black rectangles while those homologous for NgoΦ1 and NgoΦ3 as white open rectangles. The broken line representing the genome of NgoΦ3 (between CDSs 1640 and 1649) shows the site where the integrity of this genome is broken by the presence of part of the NgoΦ7 genome). The numbers at the beginning and end of each phage show the lengths of prophage genomes (in bp) while the numbers in parenthesis show the positions of prophages in FA1090 chromosome

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-6

cds488, induction with arabinose

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-5

cds479) cells induced with arabinose. The arrow shows the time when the heat induced cultures were transferred into 37°C

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-3

<p><b>Copyright information:</b></p><p>Taken from "Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage"</p><p>http://www.biomedcentral.com/1471-2180/7/66</p><p>BMC Microbiology 2007;7():66-66.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1931599.</p><p></p> NgoΦ5 CDS729 encoding the putative repressor, C. Detection of the CDS1636 encoding putative gene of NgoΦ3. Lanes 1, 5, 13; FA1090, lanes 2, 6; WR302, Lanes 3, 8; 11, MS11, Lanes 4,7,10; . WR220, Lanes 9, 12, 1291. M, molecular weight marker

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-9

<p><b>Copyright information:</b></p><p>Taken from "Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage"</p><p>http://www.biomedcentral.com/1471-2180/7/66</p><p>BMC Microbiology 2007;7():66-66.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1931599.</p><p></p>led 1 through 5. These bars represent prophages NgoI-5 respectively

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-0

<p><b>Copyright information:</b></p><p>Taken from "Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage"</p><p>http://www.biomedcentral.com/1471-2180/7/66</p><p>BMC Microbiology 2007;7():66-66.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1931599.</p><p></p>led 1 through 5. These bars represent prophages NgoI-5 respectively

Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage-7

<p><b>Copyright information:</b></p><p>Taken from "Characterization of the dsDNA prophage sequences in the genome of and visualization of productive bacteriophage"</p><p>http://www.biomedcentral.com/1471-2180/7/66</p><p>BMC Microbiology 2007;7():66-66.</p><p>Published online 5 Jul 2007</p><p>PMCID:PMC1931599.</p><p></p>onding to large terminase encoded by CDS488 (Lane A1) or CDS1116 (Lane A2). In the control experiment the PCR product corresponding to the chromosomal DNA sequence of FA1090 encoding the lpt3 gene was not detected (Lane A3) in the phage preparation while the same PCR product was formed using the chromosomal DNA as a substrate (Lane B1)