DNA repair in reduced genome: The Mycoplasma model

Carvalho, Fabíola Marques de; Fonseca, Maira Christina Marques; Medeiros, Sílvia Regina Batistuzzo de; Scortecci, Kátia Castanho; Blaha, Carlos Alfredo Galindo; Agnez-Lima, Lucymara Fassarella

doi:10.1016/j.gene.2005.06.012

Cited by 51 publications

(58 citation statements)

References 31 publications

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“…In addition, interstrain, whole-genome comparisons have not yet been carried out, although the genes involved in DNA repair, including those of the organisms herein studied, have recently been analyzed (10).…”

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confidence: 99%

Swine and Poultry Pathogens: the Complete Genome Sequences of Two Strains ofMycoplasma hyopneumoniaeand a Strain ofMycoplasma synoviae

et al. 2005

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This work reports the results of analyses of three complete mycoplasma genomes, a pathogenic (7448) and a nonpathogenic (J) strain of the swine pathogen Mycoplasma hyopneumoniae and a strain of the avian pathogen Mycoplasma synoviae; the genome sizes of the three strains were 920,079 bp, 897,405 bp, and 799,476 bp, respectively. These genomes were compared with other sequenced mycoplasma genomes reported in the literature to examine several aspects of mycoplasma evolution. Strain-specific regions, including integrative and conjugal elements, and genome rearrangements and alterations in adhesin sequences were observed in the M. hyopneumoniae strains, and all of these were potentially related to pathogenicity. Genomic comparisons

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confidence: 99%

Swine and Poultry Pathogens: the Complete Genome Sequences of Two Strains ofMycoplasma hyopneumoniaeand a Strain ofMycoplasma synoviae

et al. 2005

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“…A comparative analysis of the homologous recombination components present in various bacteria genomes suggests that the recombination machinery in M. genitalium is reduced and lacks important initiation enzymes such as RecBCD, RecQ, or RecFOR (4,45). The lack of such important presynaptic proteins has also been observed for other bacterial pathogens, including the highly recombinant Helicobacter pylori (45,54), suggesting that for many organisms, presynaptic functions are performed by other enzymes not identified in current genome annotations.…”

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confidence: 99%

Intrastrain Heterogeneity of the mgpB Gene in Mycoplasma genitalium Is Extensive In Vitro and In Vivo and Suggests that Variation Is Generated via Recombination with Repetitive Chromosomal Sequences

Iverson-Cabral¹,

et al. 2006

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Mycoplasma genitalium is associated with reproductive tract disease in women and may persist in the lower genital tract for months, potentially increasing the risk of upper tract infection and transmission to uninfected partners. Despite its exceptionally small genome (580 kb), approximately 4% is composed of repeated elements known as MgPar sequences (MgPa repeats) based on their homology to the mgpB gene that encodes the immunodominant MgPa adhesin protein. The presence of these MgPar sequences, as well as mgpB variability between M. genitalium strains, suggests that mgpB and MgPar sequences recombine to produce variant MgPa proteins. To examine the extent and generation of diversity within single strains of the organism, we examined mgpB variation within M. genitalium strain G-37 and observed sequence heterogeneity that could be explained by recombination between the mgpB expression site and putative donor MgPar sequences. Similarly, we analyzed mgpB sequences from cervical specimens from a persistently infected woman (21 months) and identified 17 different mgpB variants within a single infecting M. genitalium strain, confirming that mgpB heterogeneity occurs over the course of a natural infection. These observations support the hypothesis that recombination occurs between the mgpB gene and MgPar sequences and that the resulting antigenically distinct MgPa variants may contribute to immune evasion and persistence of infection.Mycoplasma genitalium has been identified as a possible cause of several reproductive tract disease syndromes including urethritis in men and mucopurulent cervicitis, endometritis, pelvic inflammatory disease, and tubal factor infertility in women (3,6,7,18,23,28,30,34,35,41,48,52,55,56). When untreated (or inappropriately treated), this organism persists at infected sites as demonstrated by its association with chronic nongonococcal urethritis in men (22, 53) and its persistence for months, if not years, in the lower genital tract of women (C. R. Cohen, M. Nosek, A. Meier, S. G. Astete, S. Iverson-Cabral, N. R. Mugo, and P. A. Totten, submitted for publication). The longevity of M. genitalium infection in the human reproductive tract suggests that this pathogen may have mechanism(s) to modulate or evade the host immune response.At 580 kb, the M. genitalium G-37 T genome is one of the smallest of any self-replicating cellular organism (9, 17, 49), yet 4% of the fully sequenced genome consists of repeated elements (43) designated as MgPa repeats or MgPar sequences (17). These repeat sequences are so named because they are composed of partial, incomplete copies of the mgpB gene, which encodes the MgPa protein that mediates attachment to various cell types, including the ciliated epithelium of human fallopian tubes (8). Although there is only a single mgpB expression site, there are nine distinct MgPar sequences found throughout the genome (17). The MgPa protein is antigenic and elicits an immune response in animal models (25, 37) and in women with tubal factor infertility (6). The presence...

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“…4B). (4,6,10,12). To date, only two of these accessory proteins from mollicute species have been characterized, i.e., the M. pneumoniae RuvA homolog (14) and the SSB homolog (31).…”

Section: Resultsmentioning

confidence: 99%

“…In the current study, we have focused on the putative enzymes from both M. pneumoniae and M. genitalium that may play central roles in homologous DNA recombination and DNA repair (for a review, see the work of Carvalho et al [4]). These enzymes, which are encoded by the M. pneumoniae MPN490 ORF (12) and the M. genitalium MG339 ORF, show significant sequence similarity with RecA proteins from other organisms.…”

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The Mycoplasma pneumoniae MPN490 and Mycoplasma genitalium MG339 Genes Encode RecA Homologs That Promote Homologous DNA Strand Exchange

et al. 2009

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The P1, P40, and P90 proteins of Mycoplasma pneumoniae and the MgPa and P110 proteins of Mycoplasma genitalium are immunogenic adhesion proteins that display sequence variation. Consequently, these proteins are thought to play eminent roles in immune evasive strategies. For each of the five proteins, a similar underlying molecular mechanism for sequence variation was hypothesized, i.e., modification of the DNA sequences of their respective genes. This modification is thought to result from homologous recombination of parts of these genes with repeat elements (RepMp and MgPar elements in M. pneumoniae and M. genitalium, respectively) that are dispersed throughout the bacterial genome. Proteins that are potentially involved in homologous DNA recombination have been suggested to be implicated in recombination between these repeat elements and thereby in antigenic variation. To investigate this notion, we set out to study the function of the RecA homologs that are encoded by the M. pneumoniae MPN490 and M. genitalium MG339 genes. Both proteins, which are 79% identical on the amino acid level, were found to promote recombination between homologous DNA substrates in an ATP-dependent fashion. The recombinational activities of both proteins were Mg 2؉ and pH dependent and were strongly supported by the presence of single-stranded DNA binding protein, either from M. pneumoniae or from Escherichia coli. We conclude that the MPN490-and MG339-encoded proteins are RecA homologs that have the capacity to recombine homologous DNA substrates. Thus, they may play a central role in recombination between repetitive elements in both M. pneumoniae and M. genitalium.Mycoplasma pneumoniae is a human pathogen that causes a range of respiratory infections, including atypical pneumonia. This bacterium causes up to 40% of all community-acquired pneumonias and approximately 18% of cases requiring hospitalization for children (for reviews, see references 1 and 35). The closest known relative of M. pneumoniae on the basis of sequence similarity is Mycoplasma genitalium, which is an etiological agent of various diseases of the human reproductive tract, such as urethritis (see reference 28 for a review).Although M. pneumoniae and M. genitalium represent the smallest self-replicating species regarding both cellular dimensions and genome size, it is interesting to note that a significant part of their genomes consists of repeated DNA elements. In M. pneumoniae strain M129 (6, 12), approximately 8% of the 816-kb genome is composed of variants of four different types of repetitive DNA elements (RepMP1, RepMP2/3, RepMP4, and RepMP5) (29, 34, 36), while in M. genitalium strain G-37 T , 4% of the 580-kb genome consists of MgPa repeats (or MgPar sequences) (10,26,27). Common features of the two types of repetitive elements are that (i) their representatives are similar but not identical in sequence and (ii) they are also contained in open reading frames (ORFs) encoding surface-exposed, antigenic proteins. Among these proteins is the M. pneumoniae P1 p...

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DNA repair in reduced genome: The Mycoplasma model

Cited by 51 publications

References 31 publications

Swine and Poultry Pathogens: the Complete Genome Sequences of Two Strains ofMycoplasma hyopneumoniaeand a Strain ofMycoplasma synoviae

Swine and Poultry Pathogens: the Complete Genome Sequences of Two Strains ofMycoplasma hyopneumoniaeand a Strain ofMycoplasma synoviae

Intrastrain Heterogeneity of the mgpB Gene in Mycoplasma genitalium Is Extensive In Vitro and In Vivo and Suggests that Variation Is Generated via Recombination with Repetitive Chromosomal Sequences

The Mycoplasma pneumoniae MPN490 and Mycoplasma genitalium MG339 Genes Encode RecA Homologs That Promote Homologous DNA Strand Exchange

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