Variation in a surface-exposed region of the Mycoplasma pneumoniae P40 protein as a consequence of homologous DNA recombination between RepMP5 elements

Abstract

Mycoplasma pneumoniae is a human pathogen that causes a range of respiratory tract infections. The first step in infection is adherence of the bacteria to the respiratory epithelium. This step is mediated by a specialized organelle, which contains several proteins (cytadhesins) that have an important function in adherence. Two of these cytadhesins, P40 and P90, represent the proteolytic products from a single 130 kDa protein precursor, which is encoded by the MPN142 gene. Interestingly, MPN142 contains a repetitive DNA element, termed RepMP5, of which homologues are found at seven other loci within the M. pneumoniae genome. It has been hypothesized that these RepMP5 elements, which are similar but not identical in sequence, recombine with their counterpart within MPN142 and thereby provide a source of sequence variation for this gene. As this variation may give rise to amino acid changes within P40 and P90, the recombination between RepMP5 elements may constitute the basis of antigenic variation and, possibly, immune evasion by M. pneumoniae. To investigate the sequence variation of MPN142 in relation to inter-RepMP5 recombination, we determined the sequences of all RepMP5 elements in a collection of 25 strains. The results indicate that: (i) inter-RepMP5 recombination events have occurred in seven of the strains, and (ii) putative RepMP5 recombination events involving MPN142 have induced amino acid changes in a surface-exposed part of the P40 protein in two of the strains. We conclude that recombination between RepMP5 elements is a common phenomenon that may lead to sequence variation of MPN142-encoded proteins.

Inter- and Intra-Strain Variability of Tandem Repeats in Mycoplasma Pneumoniae Based on Next-Generation Sequencing Data

“…A VNTR locus was defined as a region containing a tandem repeat unit of 2 bp or longer that was variable in the repeat copy number between any two or more of the 20 genomes analyzed. Excluded were loci related to the interspersed repetitive elements RepMPs of the MPN141 and MPN142 genes in the P1 operon due to their high sequence identify and potential to recombine with homologous sequences to generate intrastrain variation [40,41]. Also excluded were all but one (Mpn1) loci related to the multicopy hsdS gene family encoding the S subunit of type I restriction enzyme due to the high sequence identity among them [8], which prevents accurate alignment with short NGS reads.…”

Comparison of Mycoplasma pneumoniae Genome Sequences from Strains Isolated from Symptomatic and Asymptomatic Patients

“…Our previous findings on sequence variation among M. pneumoniae strains, which mainly focussed on the P1 gene and repetitive elements (RepMP sequences), showed that variation among repetitive sequences is very common in this bacterium (Spuesens et al, 2009, 2010). In the current analysis of whole-genome sequences of 20 different M. pneumoniae isolates, however, we did not identify large genomic rearrangements.…”

Macrolide-resistantMycoplasma pneumoniaein paediatric pneumonia: Table 1–

“…Although macrolide-resistant M. pneumoniae strains have been associated with prolonged fever in children [3], there are still no published data indicating that this resistant variant is inherently more pathogenic in any human host. Additionally, the appearance of macrolide resistance has been described in subtypes 1 and 2, which are characterised by sequence differences in all RepMP2/3, RepMP4 and RepMP5 repetitive elements [9]. Although the rate of variant 2a strains has increased in Europe [10], this is the first detection of macrolide resistance in this genotype.…”

“…DNA extracted from the respiratory samples using a Nuclisens EasyMAG automated extraction system (Biomeriéux, Craponne, France) was pretested by means of real-time PCR targeting a conserved inter-repetitive region of the P1 gene of M. pneumoniae [8], and the M. pneumoniae-positive samples were characterised in known subtypes and variants by sequencing a variable part of the RepMP2/3 repetitive element of the P1 gene as recently described [9]. Briefly, the nested PCR procedure amplifies a part of RepMP2/3 that shows characteristic conserved differences in the sequences of the known subtypes and variants of M. pneumoniae; sequencing the PCR product allows the reliable classification of the detected strains.…”