GAA Trinucleotide Repeat Region Regulates M9/pMGA Gene Expression in
            <i>Mycoplasma gallisepticum</i>

Liu, Li; Dybvig, Kevin; Panangala, Victor S.; Santen, Vicky L. van; French, Christopher T.

doi:10.1128/iai.68.2.871-876.2000

Cited by 50 publications

(41 citation statements)

References 15 publications

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“…The tube was vortexed for 10 sec, followed by boiling for 10 min, vortexing for 10 sec, then spinning down the beads for 3 min at 12,000g in a microfuge. PCR was performed to amplify the repetitive segment as described previously (Liu et al 2000). The products were cleaned using a Concert PCR purification kit (GibcoBRL) and sequenced using standard ABI Big Dye protocols (Applied Biosystems) at the UCSD Cancer Center DNA Sequencing Core Facility.…”

Section: Pcr and Sequencingmentioning

confidence: 99%

“…To collect independent mutants, a single lacZ+ colony was resuspended and spread on a plate containing X-gal. Growth conditions and blue/white analysis were as described previously (Liu et al 2000). Blue colonies were then picked from this plate, such that each was derived from a blue cell.…”

Section: Collection Of Independent Mutantsmentioning

confidence: 99%

“…One of us (L.L.) had previously replaced the affected pMGA gene with a lacZ reporter, allowing visual identification of mutants (Liu et al 2000). These mutants arose in separate laboratory cultures, which both insured their independence and minimized the potential effects of natural selection on the distribution of observed mutations.…”

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confidence: 99%

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Domain-Level Differences in Microsatellite Distribution and Content Result from Different Relative Rates of Insertion and Deletion Mutations

Metzgar¹,

Liu²,

Hansen³

et al. 2002

Genome Res.

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Microsatellites (short tandem polynucleotide repeats) are found throughout eukaryotic genomes at frequencies many orders of magnitude higher than the frequencies predicted to occur by chance. Most of these microsatellites appear to have evolved in a generally neutral manner. In contrast, microsatellites are generally absent from bacterial genomes except in locations where they provide adaptive functional variability, and these appear to have evolved under selection. We demonstrate a mutational bias towards deletion (repeat contraction) in a native chromosomal microsatellite of the bacterium Mycoplasma gallisepticum, through the collection and analysis of independent mutations in the absence of natural selection. Using this and similar existing data from two other bacterial species and four eukaryotic species, we find strong evidence that deletion biases resulting in repeat contraction are common in bacteria, while eukaryotic microsatellites generally experience unbiased mutation or a bias towards insertion (repeat expansion). This difference in mutational bias suggests that eukaryotic microsatellites should generally expand wherever selection does not exclude them, whereas bacterial microsatellites should be driven to extinction by mutational pressure wherever they are not maintained by selection. This is consistent with observed bacterial and eukaryotic microsatellite distributions. Hence, mutational biases that differ between eukaryotes and bacteria can account for many of the observed differences in microsatellite DNA content and distribution found in these two groups of organisms.

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Section: Pcr and Sequencingmentioning

confidence: 99%

Section: Collection Of Independent Mutantsmentioning

confidence: 99%

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Domain-Level Differences in Microsatellite Distribution and Content Result from Different Relative Rates of Insertion and Deletion Mutations

Metzgar¹,

Liu²,

Hansen³

et al. 2002

Genome Res.

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“…DNA rearrangements involving these repetitive elements have not been well characterized but may resemble gene conversion. In Mycoplasma gallisepticum, the phase-variable expression of members of the pMGA gene family is apparently controlled by the length of the trinucleotide GAA tandem repeat region located upstream of each gene's transcription start site (20,25). The mechanism by which the GAA repeats influence pMGA gene expression is unknown.…”

Section: Discussionmentioning

confidence: 99%

Gene Rearrangements in the vsa Locus of Mycoplasma pulmonis

Shen

Gumulak

et al. 2000

J Bacteriol

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The vsa genes of Mycoplasma pulmonis encode the V-1 lipoproteins. Most V-1 proteins contain repetitive domains and are thought to be involved in mycoplasma-host cell interactions. Previously, we have reported the isolation and characterization of six vsa genes comprising a 10-kb region of the genome of M. pulmonis strain KD735-15. In the current study, vsa-specific probes were used to clone several fragments from a genomic library of KD735-15 DNA and assemble a single 20-kb contig containing 11 vsa genes. The middle region of the vsa locus contains a large open reading frame (ORF) that is not a vsa gene and has undergone an internal deletion in some strains. The ORF is predicted to encode a membrane protein that may have a role in disease pathogenesis. To examine vsa genes in a strain of M. pulmonis that is unrelated to KD735-15, strain CT was studied. Through Southern hybridization and genomic cloning analyses, CT was found to possess homologs of the KD735-15 vsaA, -C, -E, and -F genes and two unique genes (vsaG and vsaH) that were not found in KD735-15. High-frequency, site-specific DNA inversions serve to regulate the phase-variable production of individual V-1 proteins. As a result of the sequence analysis of vsa recombination products, a model in which DNA inversion arises from strand exchange involving at least six nucleotides of the vrs box is proposed.Mycoplasmas cause slowly progressive, chronic diseases in human and animals. The mechanisms of mycoplasmal disease pathogenesis are poorly understood, and there are no effective control measures. Mycoplasma pulmonis is the etiologic agent of murine respiratory mycoplasmosis and can also cause genital disease and arthritis in rats and mice (31). Thus, M. pulmonis can colonize a variety of epithelial surfaces. Rat isolates of M. pulmonis such as strains UAB 5782 and UAB 6510 are generally more virulent in rats than in mice (10,11,24). In the mouse, UAB 5782 and UAB 6510 colonize the respiratory tract without usually causing lesions (10). In contrast, the mouse isolate strain CT causes severe respiratory disease in the mouse (6,7,10,12). Mycoplasma factors that contribute to the host specificity of disease are unknown. A comparison of the proteins produced by 18 strains of M. pulmonis revealed mostly conserved proteins that were invariant among strains (38). An exception was the V-1 family of surface proteins that are encoded by the vsa (variable surface antigen) genes (4,21,33,35,39). Variation in the V-1 proteins may contribute to the host specificity of the mycoplasma and to the chronicity and severity of disease.The chronic nature of mycoplasmal diseases indicates that mycoplasmas can adapt to the rapidly changing conditions in the host. Previous studies had shown that phenotypic variation and genetic recombination occur at high frequencies in M. pulmonis (3). The vsa genes comprise one of the highly recombinogenic loci in this species. Recombination between vsa genes involves site-specific DNA inversions occurring at a 34-bp sequence that defines the vsa ...

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“…Studies in Escherichia coli showed that these TRS, such as (CTG) n and (CGG) n , may effect genetic instability during DNA replication, transcription, and repair processes (17). (GAA) 12 has been found in a plasmid of Mycoplasma gallisepticum (12,13), and it positively regulates gene expression in this plasmid. It is not as well known whether bacterial genomes possess tandem repeat sequences.…”

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confidence: 99%

Characterization of a Trinucleotide Repeat Sequence (CGG) ₅ and Potential Use in Restriction Fragment Length Polymorphism Typing of Mycobacterium tuberculosis

et al. 2004

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The genomes of 28 bacterial strains, including mycobacterial species Mycobacterium tuberculosis and Mycobacterium bovis, were analyzed for the presence of a special class of microsatellite, that of trinucleotide repeat sequences (TRS). Results of a search of all 10 possible TRS motifs (i.e., CCT, CGG, CTG, GAA, GAT, GTA, GTC, GTG, GTT, and TAT) with five or more repeating units showed that (CGG) 5 DNA fingerprinting of the inserted IS6110 element specific for the Mycobacterium tuberculosis complex is a powerful epidemiological tool for visualizing DNA restriction fragment length polymorphisms (RFLP) of M. tuberculosis (26). The major limitation of IS6110-based RFLP typing is the difficulty of discriminating genetic polymorphisms of M. tuberculosis isolates with only a few copies of the element. In addition, there are two reports (1, 29) that described IS6110-based RFLP as unstable, although other studies have confirmed a high degree of stability (5, 15). Yeh and colleagues (29) indicated that genotypes with IS6110 were relatively unstable because they changed rapidly compared with those based on another marker. Alito et al. (1) reported that a multidrugresistant outbreak strain changed rapidly, according to IS6110 RFLP, over a period of a few years.

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GAA Trinucleotide Repeat Region Regulates M9/pMGA Gene Expression in Mycoplasma gallisepticum

Cited by 50 publications

References 15 publications

Domain-Level Differences in Microsatellite Distribution and Content Result from Different Relative Rates of Insertion and Deletion Mutations

Domain-Level Differences in Microsatellite Distribution and Content Result from Different Relative Rates of Insertion and Deletion Mutations

Gene Rearrangements in the vsa Locus of Mycoplasma pulmonis

Characterization of a Trinucleotide Repeat Sequence (CGG) ₅ and Potential Use in Restriction Fragment Length Polymorphism Typing of Mycobacterium tuberculosis

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GAA Trinucleotide Repeat Region Regulates M9/pMGA Gene Expression in Mycoplasma gallisepticum

Cited by 50 publications

References 15 publications

Domain-Level Differences in Microsatellite Distribution and Content Result from Different Relative Rates of Insertion and Deletion Mutations

Domain-Level Differences in Microsatellite Distribution and Content Result from Different Relative Rates of Insertion and Deletion Mutations

Gene Rearrangements in the vsa Locus of Mycoplasma pulmonis

Characterization of a Trinucleotide Repeat Sequence (CGG) 5 and Potential Use in Restriction Fragment Length Polymorphism Typing of Mycobacterium tuberculosis

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Product

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Characterization of a Trinucleotide Repeat Sequence (CGG) ₅ and Potential Use in Restriction Fragment Length Polymorphism Typing of Mycobacterium tuberculosis