<i>Mycoplasma arthritidis</i>-derived superantigen (MAM) displays DNase activity

Diedershagen, Markus; Overbeck, Silke; Arlt, Sabine; Plümäkers, Birgit; Lintges, Maria; Rink, Lothar

doi:10.1111/j.1574-695x.2006.00189.x

Cited by 12 publications

(17 citation statements)

References 34 publications

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“…The gene product has a signal peptide sequence that is absent in the mature, secreted protein of 213 amino acids (4). In addition to its superantigen activity, MAM also has nuclease activity (8). Marth_orf729 is predicted to code for a protein that shares 49.4% amino acid identity with MAM.…”

Section: Resultsmentioning

confidence: 99%

Genome of Mycoplasma arthritidis

et al. 2008

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The genomes of several species of mycoplasma have been sequenced. Most of these species rely on the glycolytic pathway for energy production, with the one exception of Ureaplasma, a species that breaks down urea as its principle source of acquiring energy. Several species, including as Mycoplasma arthritidis, are nonglycolytic and can use arginine as their source of energy. Described here are the genome sequence and a transposon library of M. arthritidis. The genome of 820,453 bp is typical in size for a mycoplasma and contains two large families of genes that are predicted to code for phase-variable proteins. The transposon library was constructed using a minitransposon that inserts stably into the mycoplasma genome. Of the 635 predicted coding regions, 218 were disrupted in a library of 1,100 members. Dispensable genes included the gene coding for the MAM superantigen and genes coding for ribosomal proteins S15, S18, and L15.Mycoplasma arthritidis is a natural pathogen of rats, causing severe polyarthritis. Arthritis in mice can be experimentally induced by injection of M. arthritidis into the tail vein. Disease in mice is more chronic than in rats, with lesions similar to those seen in human rheumatoid arthritis (25). Factors thought to contribute to the virulence of M. arthritidis are MAM, a potent superantigen secreted by the mycoplasma, and the M. arthritidis adhesins (MAAs) that have a role in cytadherence (32).The genome sequences of several species of mycoplasma are known (see http://cbi.labri.fr/outils/molligen/). Other than Ureaplasma, which utilizes the hydrolysis of urea to generate ATP, all of the mycoplasma species that have sequenced genomes are glycolytic. Some species of mycoplasma such as M. arthritidis are nonglycolytic, and thus it was anticipated that the sequence of the M. arthritidis genome would reveal new aspects of mycoplasma physiology. Nonglycolytic mycoplasmas generally catabolize arginine as a major source of energy, and, indeed, the required genes for arginine catabolism were identified in the genome sequence of M. arthritidis.Described here is the genome sequence of the virulent M. arthritidis strain 158L3-1 (3, 31). Strain 158L3-1 is a lysogen containing the 16-kb genome of the MAV1 bacteriophage. No additional prophages were noted in the genome. The sequence revealed features offering insight into the mechanisms by which the mycoplasma causes chronic inflammation, including two families of genes that are predicted to code for phasevariable proteins and a predicted gene product related to but distinct from MAM.We also describe a transposon library of M. arthritidis strain 158, the nonlysogenic parent of 158L3-1. The library was created using minitransposons derived from Tn4001 that inserts into the genome at essentially random sites. The genomic location of the minitransposon was determined for 1,113 library members. Using criteria for gene inactivation previously developed for transposon mutagenesis of Mycoplasma pulmonis, 218 of the predicted protein coding regions, including ...

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Section: Resultsmentioning

confidence: 99%

Genome of Mycoplasma arthritidis

et al. 2008

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“…Nonantibiotic resistance markers have also been developed, including bar, which encodes resistance to the herbicide DL-phosphinothricin (38); merA, which provides resistance to organomercurial compounds (21); and arsAB, which express arsenite resis-tance proteins (9). Plasmid-based expression (PBE) systems can express antigens at high levels; however, high levels of expression of some antigens can have a growth-inhibitory effect (10,51) and thus can reduce the efficacy of the live delivery system.…”

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confidence: 99%

Development of Non-Antibiotic-Resistant, Chromosomally Based, Constitutive and Inducible Expression Systems for aroA -Attenuated Salmonella enterica Serovar Typhimurium

et al. 2009

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Live-vaccine delivery systems expressing two model antigens from Mycoplasma hyopneumoniae, F2 P97 (Adh) and NrdF, were constructed using Salmonella enterica serovar Typhimurium aroA (STM-1), and immunogenicity in mice was evaluated. Recombinant plasmid-based expression (PBE) and chromosomally based expression (CBE) systems were constructed. The PBE system was formed by cloning both antigen genes into pJLA507 to create an operon downstream of temperature-inducible promoters. Constitutive CBE was achieved using a promoter-trapping technique whereby the promoterless operon was stably integrated into the chromosome of STM-1, and the expression of antigens was assessed. The chromosomal position of the operon was mapped in four clones. Inducible CBE was obtained by using the in vivo-induced sspA promoter and recombining the expression construct into aroD. Dual expression of the antigens was detected in all systems, with PBE producing much larger quantities of both antigens. The stability of antigen expression after in vivo passage was 100% for all CBE strains recovered. PBE and CBE strains were selected for comparison in a vaccination trial. The vaccine strains were delivered orally into mice, and significant systemic immunoglobulin M (IgM) and IgG responses against both antigens were detected among all CBE groups. No significant immune response was detected using PBE strains. Expression of recombinant antigens in S. enterica serovar Typhimurium aroA from chromosomally located strong promoters without the use of antibiotic resistance markers is a reliable and effective method of inducing a significant immune response.The use of live, attenuated bacteria as vaccine delivery systems for heterologous antigens has been extensively studied. In particular, attenuated Salmonella strains have been modified to express a wide range of antigens from bacterial, parasitic, and viral sources (reviewed in references 20, 29, and 41). After oral administration, Salmonella can penetrate the Peyer's patches via M cells and colonize the mesenteric lymph nodes, which contain various antigen-presenting cells (reviewed in reference 5). This can generate a range of immune responses, including systemic and mucosal responses at local and distal sites. Other advantages of using attenuated Salmonella include the ease of oral administration, which bypasses the need for needle administration; increased antigen presentation due to the use of a live-vector delivery system, the induction of both Th1 and Th2 immune responses; and the wide range of attenuated Salmonella and recombinant vectors available to researchers (19,20,51).However, there are a number of issues to overcome. Most methods for the expression of heterologous antigens in Salmonella use plasmids to express the antigenic proteins. This can have several drawbacks. The stable maintenance of the expression plasmid in vivo can be difficult to achieve. Tightly regulated promoters are often used to increase plasmid stability, and several in vivo-inducible promoters have delivered promising res...

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“…Several of these nucleases have been demonstrated to contribute to pathogenicity and cytotoxicity (38,39). In addition, the M. arthritidis-derived mitogen (MAM) has been demonstrated to exhibit DNase activity (40).…”

Section: Discussionmentioning

confidence: 99%

Disruption of the Membrane Nuclease Gene (MBOVPG45_0215) of Mycoplasma bovis Greatly Reduces Cellular Nuclease Activity

et al. 2015

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Although the complete genome sequences of three strains of Mycoplasma bovis are available, few studies have examined gene function in this important pathogen. Mycoplasmas lack the biosynthetic machinery for the de novo synthesis of nucleic acid precursors, so nucleases are likely to be essential for them to acquire nucleotide precursors. Three putative membrane nucleases have been annotated in the genome of M. bovis strain PG45, MBOVPG45_0089 and MBOVPG45_0310, both of which have the thermonuclease (TNASE_3) functional domain, and MBOVPG45_0215 (mnuA), which has an exonuclease/endonuclease/phosphatase domain. While previous studies have demonstrated the function of TNASE_3 domain nucleases in several mycoplasmas, quantitative comparisons of the contributions of different nucleases to cellular nuclease activity have been lacking. Mapping of a library of 319 transposon mutants of M. bovis PG45 by direct genome sequencing identified mutants with insertions in MBOVPG45_0310 (the ⌬0310 mutant) and MBOVPG45_0215 (the ⌬0215 mutant). In this study, the detection of the product of MBOVPG45_0215 in the Triton X-114 fraction of M. bovis cell lysates, its cell surface exposure, and its predicted signal peptide suggested that it is a surface-exposed lipoprotein nuclease. Comparison of a ⌬mnuA mutant with wild-type M. bovis on native and denatured DNA gels and in digestion assays using double-stranded phage DNA and closed circular plasmid DNA demonstrated that inactivation of this gene abolishes most of the cellular exonuclease and endonuclease activity of M. bovis. This activity could be fully restored by complementation with the wild-type mnuA gene, demonstrating that MnuA is the major cellular nuclease of M. bovis. IMPORTANCENucleases are thought to be important contributors to virulence and crucial for the maintenance of a nutritional supply of nucleotides in mycoplasmas that are pathogenic in animals. This study demonstrates for the first time that of the three annotated cell surface nuclease genes in an important pathogenic mycoplasma, the homologue of the thermostable nuclease identified in Gram-positive bacteria is responsible for the majority of the nuclease activity detectable in vitro.A lthough the complete genomes of many Mycoplasma species are now available, the scarcity of tools for exploring their molecular biology has resulted in an understanding of the function of their genes more rudimentary than that which is available for many other prokaryotes. The genomes of three strains of the important bovine pathogen Mycoplasma bovis, the type strain PG45, the Hubei-1 strain, and the HB0801 strain, have been sequenced and published recently (1-3), but apart from several reports on phase switching in M. bovis (4-7), few studies have examined the molecular mechanisms underlying their pathogenicity and virulence or the metabolic functions of the products of their genes.Mycoplasmas evolved from Clostridium-like bacteria by a process of reductive evolution and are believed to have retained only the regulatory and ...

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Mycoplasma arthritidis-derived superantigen (MAM) displays DNase activity

Cited by 12 publications

References 34 publications

Genome of Mycoplasma arthritidis

Genome of Mycoplasma arthritidis

Development of Non-Antibiotic-Resistant, Chromosomally Based, Constitutive and Inducible Expression Systems for aroA -Attenuated Salmonella enterica Serovar Typhimurium

Disruption of the Membrane Nuclease Gene (MBOVPG45_0215) of Mycoplasma bovis Greatly Reduces Cellular Nuclease Activity

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