Limits...
Mycoplasma genitalium: an efficient strategy to generate genetic variation from a minimal genome.

Ma L, Jensen JS, Myers L, Burnett J, Welch M, Jia Q, Martin DH - Mol. Microbiol. (2007)

Bottom Line: In order to establish the origin of the MG192 variants, we examined nine genomic loci containing partial copies of the MgPa operon, known as MgPar sequences.Our analysis suggests that the MG192 sequence variation is achieved by recombination between the MG192 expression site and MgPar sequences via gene cross-over and, possibly, also by gene conversion.It appears plausible that M. genitalium has the ability to generate unlimited variants from its minimized genome, which presumably allows the organism to adapt to diverse environments and/or to evade host defences by antigenic variation.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA. lma1@lsuhsc.edu

ABSTRACT
Mycoplasma genitalium, a human pathogen associated with sexually transmitted diseases, is unique in that it has smallest genome of any known free-living organism. The goal of this study was to investigate if and how M. genitalium uses a minimal genome to generate genetic variations. We analysed the sequence variability of the third gene (MG192 or mgpC) of the M. genitalium MgPa adhesion operon, demonstrated that the MG192 gene is highly variable among and within M. genitalium strains in vitro and in vivo, and identified MG192 sequence shifts in the course of in vitro passage of the G37 type strain and in sequential specimens from an M. genitalium-infected patient. In order to establish the origin of the MG192 variants, we examined nine genomic loci containing partial copies of the MgPa operon, known as MgPar sequences. Our analysis suggests that the MG192 sequence variation is achieved by recombination between the MG192 expression site and MgPar sequences via gene cross-over and, possibly, also by gene conversion. It appears plausible that M. genitalium has the ability to generate unlimited variants from its minimized genome, which presumably allows the organism to adapt to diverse environments and/or to evade host defences by antigenic variation.

Show MeSH

Related in: MedlinePlus

MG192 sequence variation among M. genitalium ATCC strains and their derivatives cultured in vitro. A. Diagram of the full-length MG192 gene of G37T, as shown in Fig. 1. B. Schematic drawing of the MG192 variable regions from M. genitalium strains cultured in vitro (see Table 1). Regions showing the longest stretch of sequence identity with the MgPars of G37T are indicated by identical patterns, as shown in the key. Numbers bordering each shaded area correspond to the nucleotide positions in the full-length MG192 gene of G37T. Triangle indicates the location of the AGT tandem repeats, with detailed information on repeat numbers shown in Table 2. Diamond indicates a single-nucleotide substitution from A to G. The sequences of the MG192 genes for G37-P35, TW48-5G and TW10-5G.ATCC have been submitted to GenBank under Accession No. EF117280, EF117281 and EF117282 respectively.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2169797&req=5

fig02: MG192 sequence variation among M. genitalium ATCC strains and their derivatives cultured in vitro. A. Diagram of the full-length MG192 gene of G37T, as shown in Fig. 1. B. Schematic drawing of the MG192 variable regions from M. genitalium strains cultured in vitro (see Table 1). Regions showing the longest stretch of sequence identity with the MgPars of G37T are indicated by identical patterns, as shown in the key. Numbers bordering each shaded area correspond to the nucleotide positions in the full-length MG192 gene of G37T. Triangle indicates the location of the AGT tandem repeats, with detailed information on repeat numbers shown in Table 2. Diamond indicates a single-nucleotide substitution from A to G. The sequences of the MG192 genes for G37-P35, TW48-5G and TW10-5G.ATCC have been submitted to GenBank under Accession No. EF117280, EF117281 and EF117282 respectively.

Mentions: We examined the MG192 variable region in M. genitalium American Type Culture Collection (ATCC) strains and their derivatives (Table 1). A fragment of approximately 1.7 kb covering the entire MG192 variable region was amplified by PCR and sequenced directly and after subcloning. For each strain, we identified a mixture of two or three MG192 sequences that differed from each other only in the number of the AGT tandem repeats (Table 2). Aside from the AGT repeat number variation, the MG192 sequences in all ATCC strains except for TW48-5G and TW10-5G were identical to that of the published G37T genome sequence (Fig. 2). The MG192 sequence of TW48-5G contained a total of 28 nucleotide substitutions and one triplet deletion in the regions flanking the AGT tandem repeats compared with the G37T genome sequence. The MG192 sequence of TW10-5G (designated as TW10-5G.ATCC in Fig. 2) had 67 nucleotide substitutions, three triplet insertions and one triplet deletion upstream of the AGT repeats. These nucleotide substitutions, insertions and deletions did not cause frameshifts or stop codons in the predicted ORF but did code for different amino acid sequences.


Mycoplasma genitalium: an efficient strategy to generate genetic variation from a minimal genome.

Ma L, Jensen JS, Myers L, Burnett J, Welch M, Jia Q, Martin DH - Mol. Microbiol. (2007)

MG192 sequence variation among M. genitalium ATCC strains and their derivatives cultured in vitro. A. Diagram of the full-length MG192 gene of G37T, as shown in Fig. 1. B. Schematic drawing of the MG192 variable regions from M. genitalium strains cultured in vitro (see Table 1). Regions showing the longest stretch of sequence identity with the MgPars of G37T are indicated by identical patterns, as shown in the key. Numbers bordering each shaded area correspond to the nucleotide positions in the full-length MG192 gene of G37T. Triangle indicates the location of the AGT tandem repeats, with detailed information on repeat numbers shown in Table 2. Diamond indicates a single-nucleotide substitution from A to G. The sequences of the MG192 genes for G37-P35, TW48-5G and TW10-5G.ATCC have been submitted to GenBank under Accession No. EF117280, EF117281 and EF117282 respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169797&req=5

fig02: MG192 sequence variation among M. genitalium ATCC strains and their derivatives cultured in vitro. A. Diagram of the full-length MG192 gene of G37T, as shown in Fig. 1. B. Schematic drawing of the MG192 variable regions from M. genitalium strains cultured in vitro (see Table 1). Regions showing the longest stretch of sequence identity with the MgPars of G37T are indicated by identical patterns, as shown in the key. Numbers bordering each shaded area correspond to the nucleotide positions in the full-length MG192 gene of G37T. Triangle indicates the location of the AGT tandem repeats, with detailed information on repeat numbers shown in Table 2. Diamond indicates a single-nucleotide substitution from A to G. The sequences of the MG192 genes for G37-P35, TW48-5G and TW10-5G.ATCC have been submitted to GenBank under Accession No. EF117280, EF117281 and EF117282 respectively.
Mentions: We examined the MG192 variable region in M. genitalium American Type Culture Collection (ATCC) strains and their derivatives (Table 1). A fragment of approximately 1.7 kb covering the entire MG192 variable region was amplified by PCR and sequenced directly and after subcloning. For each strain, we identified a mixture of two or three MG192 sequences that differed from each other only in the number of the AGT tandem repeats (Table 2). Aside from the AGT repeat number variation, the MG192 sequences in all ATCC strains except for TW48-5G and TW10-5G were identical to that of the published G37T genome sequence (Fig. 2). The MG192 sequence of TW48-5G contained a total of 28 nucleotide substitutions and one triplet deletion in the regions flanking the AGT tandem repeats compared with the G37T genome sequence. The MG192 sequence of TW10-5G (designated as TW10-5G.ATCC in Fig. 2) had 67 nucleotide substitutions, three triplet insertions and one triplet deletion upstream of the AGT repeats. These nucleotide substitutions, insertions and deletions did not cause frameshifts or stop codons in the predicted ORF but did code for different amino acid sequences.

Bottom Line: In order to establish the origin of the MG192 variants, we examined nine genomic loci containing partial copies of the MgPa operon, known as MgPar sequences.Our analysis suggests that the MG192 sequence variation is achieved by recombination between the MG192 expression site and MgPar sequences via gene cross-over and, possibly, also by gene conversion.It appears plausible that M. genitalium has the ability to generate unlimited variants from its minimized genome, which presumably allows the organism to adapt to diverse environments and/or to evade host defences by antigenic variation.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA. lma1@lsuhsc.edu

ABSTRACT
Mycoplasma genitalium, a human pathogen associated with sexually transmitted diseases, is unique in that it has smallest genome of any known free-living organism. The goal of this study was to investigate if and how M. genitalium uses a minimal genome to generate genetic variations. We analysed the sequence variability of the third gene (MG192 or mgpC) of the M. genitalium MgPa adhesion operon, demonstrated that the MG192 gene is highly variable among and within M. genitalium strains in vitro and in vivo, and identified MG192 sequence shifts in the course of in vitro passage of the G37 type strain and in sequential specimens from an M. genitalium-infected patient. In order to establish the origin of the MG192 variants, we examined nine genomic loci containing partial copies of the MgPa operon, known as MgPar sequences. Our analysis suggests that the MG192 sequence variation is achieved by recombination between the MG192 expression site and MgPar sequences via gene cross-over and, possibly, also by gene conversion. It appears plausible that M. genitalium has the ability to generate unlimited variants from its minimized genome, which presumably allows the organism to adapt to diverse environments and/or to evade host defences by antigenic variation.

Show MeSH
Related in: MedlinePlus