Shared epitopes between Mycoplasma pneumoniae major adhesin protein P1 and a 140-kilodalton protein of Mycoplasma genitalium

Previous serological data have demonstrated cross-reactive antigens between two pathogenic species of mycoplasmas, M. pneumoniae and M. genitalium. Preliminary analysis of sera and monoclonal antibodies (MAbs) to protein antigens of these species showed an immunodominance of adhesin P1 (165 kilodaltons [kDa]) of M. pneumoniae in mice and hamsters and a 140-kDa protein of M. genitalium in mice and experimentally infected chimpanzees. To further characterize these two proteins, we assayed multiple anti-P1 and anti-140-kDa protein MAbs by enzyme-linked immunosorbent assay, immunoblot, and radioimmunoprecipitation techniques. The 140-kDa M. genitalium protein was shown to be surface accessible and insensitive to levels of trypsin which readily degrade protein P1. Peptide mapping was used to identify a unique class of MAbs which bound a cross-reactive molecule common to both the major adhesin protein P1 of M. pneumoniae and the 140-kDa protein of M. genitalium. MAbs generated against both M. pneumoniae and M. genitalium which were reactive with this determinant blocked M. pneumoniae attachment to chicken erythrocytes.     

Cross-hybridization between the cytadhesin genes of Mycoplasma pneumoniae and Mycoplasma genitalium and genomic DNA of Mycoplasma gallisepticum

Immunological cross-reactivity was observed between the cytadhesin proteins of Mycoplasma pneumoniae and Mycoplasma genitalium and a 155 kDa protein of Mycoplasma gallisepticum. Furthermore, the cytadhesin genes of M. pneumoniae and M. genitalium were used to demonstrate homology with M. gallisepticum genomic DNA under low stringency conditions suggesting that a family of adhesin-related genes exists among these pathogenic mycoplasmas.     

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

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 Mg²⁺ 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 protein, which plays an essential role in bacterial adhesion to host cells (2). The ORF encoding the P1 protein, MPN141, contains both a RepMP4 element and a RepMP2/3 element. It has been hypothesized that homologous recombination between these RepMP elements with elements elsewhere in the genome could generate sequence changes within MPN141. These changes could subsequently lead to amino acid sequence variation of the antigenic P1 protein and thereby contribute to bacterial evasion of the host''s immune system. Strong evidence, albeit indirect, for recombination among RepMP sequences has come from the observation that all naturally occurring sequence variations within the MPN141 gene originate from RepMP2/3 and RepMP4 elements located at distant sites within the M. pneumoniae genome (32). In addition, several RepMP2/3 and RepMP4 elements outside of the MPN141 gene, as well as RepMP1 elements, appeared to have recombined in a number of strains (24, 32). In each of these cases, RepMP sequence information seemed to be copied from the donor site to the recipient site in a unidirectional fashion, which is indicative of a gene conversion-like mechanism of homologous DNA recombination (18, 32).In analogy, the M. genitalium MgPar elements are thought to provide a pool of sequence variation of the mgpB and mgpC genes (16). These genes encode the proteins MgPa and P110, respectively, which are antigenic proteins involved in host cell attachment (3, 7, 13). Interestingly, recombination between MgPar sequences in M. genitalium appeared to be mediated by reciprocal homologous DNA recombination events rather than by unidirectional gene conversion-like processes (15, 16).In order to elucidate the molecular mechanisms that underlie recombination between RepMP elements in M. pneumoniae, we previously initiated a study aimed at the identification of proteins that may be involved in DNA recombination in this bacterium (31). 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. Here we have shown that the proteins encoded by MPN490 and MG339 promote recombination between homologous DNA substrates and may therefore play a central role in recombination between RepMP and MgPar elements in M. pneumoniae and M. genitalium, respectively.     

Mycoplasma pneumoniae and Mycoplasma genitalium mixture in synovial fluid isolate.

A mycoplasma cultured from synovial fluid specimens from a patient with pneumonia and subsequent polyarthritis was identified initially as Mycoplasma pneumoniae. In retrospective studies, the culture was shown also to contain Mycoplasma genitalium. In this paper, the laboratory techniques employed in the identification and separation of the two species are presented, and evidence to implicate postinfectious autoimmunity is provided. An increasing number of reports of M. genitalium in human tissue sites and difficulties in isolation and identification of the organism in the clinical laboratory suggest the need for more extensive application of rapid and specific detection systems for both M. genitalium and M. pneumoniae in the clinical laboratory.     

Characterisation of subtype- and variant-specific antigen regions of the P1 adhesin of Mycoplasma pneumoniae

Distinct sequence differences within the repetitive elements (RepMP) of the Mycoplasma pneumoniae P1 adhesin are the only targets to discriminate patient isolates with molecular approaches into subtypes and variants. Since the P1 protein is also one of the most immunodominant proteins of the bacterium, the antigenic regions of the differing repetitive sequences might be of epidemiological significance for the observation of time-dependent outbreaks due to defined subtypes and variants of M. pneumoniae in the human population. By establishing a set of four subtype- and variant 2-specific recombinant proteins, we investigated the antigenicity of the variable P1 protein regions with sera of subtype- and variant-specific immunised animals and sera of M. pneumoniae-positive pneumonia patients. The results of the ELISA experiments confirmed the immunogenic character of the differing parts of the P1 adhesin and the occurrence of a specific immune response of the immunised animals. The detection of subtype- and variant-specific antibodies in the investigated sera strongly support the hypothesis of a selective immune response. It might be indicative for the partial protection of the host to a defined endemic or epidemic strain and therefore also the reason for a reduced protection against secondary infections with a differing subtype and variant of M. pneumoniae strains compared to the first contact.     

Absence of Mycoplasma pneumoniae cytadsorption protein P1 in Mycoplasma genitalium and Mycoplasma gallisepticum

Polyclonal and monoclonal antibodies to Mycoplasma pneumoniae protein P1 were nonreactive with whole-cell or soluble preparations of M. genitalium and M. gallisepticum. However, radioimmunoprecipitation performed with hyperimmune rabbit sera raised against each mycoplasma species indicated antigenic cross-reactivity between M. pneumoniae and M. genitalium.     

DNA probes for detection and identification of Mycoplasma pneumoniae and Mycoplasma genitalium.

DNA probes specific for Mycoplasma pneumoniae and Mycoplasma genitalium were selected from genomic libraries prepared in pUC13. The 32P-labeled probes could detect, by dot blot hybridization, down to about 0.1 ng of the specific mycoplasma DNA or 10(5) CFU. Biotinylation of probe decreased the sensitivity of detection and produced nonspecific background reactions with nonhomologous DNAs. Sulfonation of probe yielded a similar level of sensitivity with less background.     

A Mycoplasma genitalium protein resembling the Mycoplasma pneumoniae attachment protein.

In previous studies with hyperimmune rabbit sera and monoclonal antibodies against the P1 protein of Mycoplasma pneumoniae, we obtained evidence of a shared antigenic determinant with a single protein of Mycoplasma genitalium. Because of biologic and morphologic similarities between these two human Mycoplasma species, attempts were made to characterize this cross-reacting protein of M. genitalium (designated MgPa). The protein was surface exposed and had an estimated molecular size of 140 kilodaltons. Electron microscopy with monoclonal antibodies produced against either MgPa or P1 demonstrated that MgPa is located over the surface of the terminal structure of M. genitalium which is covered by a nap layer. These immunologic and morphologic findings suggest that the MgPa protein of M. genitalium could be the counterpart of the P1 protein of M. pneumoniae.     

Expression and functional identification of the hypothetical adhesin P32 from Mycoplasma genitalium

Mycoplasma genitalium is the main causative agent for non-gonococcal and non-chlamydial urethritis. P32 is the putative surface-exposed membrane protein of M. genitalium and it has substaintial identity in amino acid sequence with adhesin protein P30 from M. pnewnoniae. Since M. pneumoniae mutants lacking P30 protein is defective in cytadherence, P32 protein has been proposed to be an essential adhesin implicated in the adherence of M. genitalium to host cells. The prokaryotic expression vector pET-30 ( )/p32 was constructed in the present study, and the recombinant protein was expressed in E. coli and purified under denaturing condition. As demonstrated by the immunoblotting analysis, the recombinant protein could react with rabbit antisera against M. genitalium, and adherence inhibition assays were petformed with antisera against this recombinant protein. It was demonstrated that P32 protein apperared to be an adhesion protein of M. genitalium, thus providing the experimental basis for better understanding of the pathogenesis of M. genitalium infection and for the development of the related vaccines against the infection.     

Immunodominant epitopes of the adhesin of Mycoplasma pneumoniae.

Overlapping octapeptides from the amino acid sequence of the adherence protein of Mycoplasma pneumoniae were synthesized and used as the antigen in an enzyme-linked immunosorbent assay with serum samples from M. pneumoniae-infected patients. Of a sequence of 338 amino acids positioned between leucine 801 and leucine 1139, only two regions with immunodominant continuous epitopes were detected. The immunoglobulin G and immunoglobulin M antibodies of child and adult patients reacted especially with the NH2-(810)-W-I-G-N-G-Y-R-Y peptide but also reacted with the NH2-(1124)-F-T-D-F-V-K-P-R peptide.     

Adhesion and inhibition assay of Mycoplasma genitalium and M. pneumoniae by immunofluorescence microscopy

Adhesion of Mycoplasma pneumoniae and the closely related M. genitalium to HEp-2 cells was investigated. The main surface proteins known to be involved in adhesion are P1 of M. pneumoniae and its homologue, MgPa, of M. genitalium. Both proteins are also immunodominant proteins. Protein P116 is another immunodominant protein of M. pneumoniae. These immunogenic proteins were investigated for their surface exposure and involvement in adhesion to host epithelial cells. Immunofluorescence microscopy (IFM) was used to detect M. pneumoniae and M. genitalium adhering to HEp-2 cells. Monospecific antibodies were produced against fragments of the surface proteins lacking tryptophan stop codons and were used for adhesion detection, surface exposure and adhesion inhibition IFM assays. Three monospecific antibodies were made against MgPa covering regions in the N-terminal, the middle and the C- terminal part; two monospecific antibodies were produced against P1 covering regions of the N- and the C-terminal part and one monospecific antibody was made against most of P116. Only the C-terminal parts of P1 and MgPa were surface exposed and blocking of these regions with the monospecific antibody resulted in inhibition of cytadsorption. Protein P116 was shown to be surface exposed and an essential protein involved in adhesion because the anti-P116 antibody prevented attachment of M. pneumoniae to the HEp-2 cells independently of P1. This study adds to the understanding of the molecular biology of M. genitalium and M. pneumoniae and presents a method to study the proteins involved in adhesion of these mycoplasmas.     

DNA and protein sequence homologies between the adhesins of Mycoplasma genitalium and Mycoplasma pneumoniae.

Mycoplasma genitalium and Mycoplasma pneumoniae are morphologically and serologically related pathogens that colonize the human host. Their successful parasitism appears to be dependent on the product, an adhesin protein, of a gene that is carried by each of these mycoplasmas. Here we describe the cloning and determine the sequence of the structural gene for the putative adhesin of M. genitalium and compare its sequence to the counterpart P1 gene of M. pneumoniae. Regions of homology that were consistent with the observed serological cross-reactivity between these adhesins were detected at both DNA and protein levels. However, the degree of homology between these two genes and their products was much higher than anticipated. Interestingly, the A + T content of the M. genitalium adhesin gene was calculated as 60.1%, which is substantially higher tham that of the P1 gene (46.5%). Comparisons of codon usage between the two organisms revealed that M. genitalium preferentially used A- and T-rich codons. A total of 65% of positions 3 and 56% of positions 1 in M. genitalium codons were either A or T, whereas M. pneumoniae utilized A or T for positions 3 and 1 at a frequency of 40 and 47%, respectively. The biased choice of the A- and T-rich codons in M. genitalium could also account for the preferential use of A- and T-rich codons in conservative amino acid substitutions found in the M. genitalium adhesin. These facts suggest that M. genitalium might have evolved independently of other human mycoplasma species, including M. pneumoniae.     

配对母婴血清和羊水β2—微球蛋白测定

目的：建立本地区母婴血清和羊水β２－微球蛋白（β２－ＭＧ）正常参考值，探讨其变化规律及作为母婴产前与前后监护指标的科学性与可行性的依据。方法：采用放射免疫法测定４０名正常未孕妇女血清和５５对正常母婴及１２对重度妊高征母婴血清和羊水中β２－ＭＧ水平。结果：（１）正常孕妇组中母血β２－ＭＧ水平极显著低于脐动脉血与羊水（均Ｐ＜０．００１）；后二者间也有差异（Ｐ＜０．０５）；三者中仅母血与脐动脉血间存在相关性（ｒ＝０．５８６，Ｐ＜０．００１）。（２）妊高征组母血和脐血β２－ＭＧ水平均显著高于正常孕妇组（分别Ｐ＜０．００１，０．００５）。结论：（１）正常参考值范围的确定有待商讨。（２）高水平的β２－ＭＧ可能是妊高征形成的原因之一，而不仅仅是其后果；且测定β２－ＭＧ可作为评估妊高征病情严重程度的敏感指标     

Detection of Mycoplasma pneumoniae adhesin (P1) in the nonhemadsorbing population of virulent Mycoplasma pneumoniae.

Mycoplasma pneumoniae organisms possessing a hemadsorbing-negative (HA-) phenotype comprise more than 50% of the population of virulent M. pneumoniae cultures. Monoclonal antibody to P1, the major adhesin of M. pneumoniae reacts with this HA- mycoplasma fraction based upon radioimmunoprecipitation and immunoblotting. Demonstration of P1 in the entire mycoplasma population suggests that topological organization of this adhesin in the membrane or the physiological state of the mycoplasmas may determine hemadsorbing capabilities.     

Amino Acid Changes in Elongation Factor Tu of Mycoplasma pneumoniae and Mycoplasma genitalium Influence Fibronectin Binding

Mycoplasma pneumoniae and Mycoplasma genitalium are closely related organisms that cause distinct clinical manifestations and possess different tissue predilections despite their high degree of genome homology. We reported earlier that surface-localized M. pneumoniae elongation factor Tu (EF-Tu_Mp) mediates binding to the extracellular matrix component fibronectin (Fn) through the carboxyl region of EF-Tu. In this study, we demonstrate that surface-associated M. genitalium EF-Tu (EF-Tu_Mg), in spite of sharing 96% identity with EF-Tu_Mp, does not bind Fn. We utilized this finding to identify the essential amino acids of EF-Tu_Mp that mediate Fn interactions by generating modified recombinant EF-Tu proteins with amino acid changes corresponding to those of EF-Tu_Mg. Amino acid changes in serine 343, proline 345, and threonine 357 were sufficient to significantly reduce the Fn binding of EF-Tu_Mp. Synthetic peptides corresponding to this region of EF-Tu_Mp (EF-Tu_Mp 340-358) blocked both recombinant EF-Tu_Mp and radiolabeled M. pneumoniae cell binding to Fn. In contrast, EF-Tu_Mg 340-358 peptides exhibited minimal blocking activity, reinforcing the specificity of EF-Tu-Fn interactions as mediators of microbial colonization and tissue tropism.Many pathogens express surface proteins that facilitate colonization and cellular invasion (12, 39, 44, 49, 55). The human mycoplasmas, Mycoplasma pneumoniae and Mycoplasma genitalium, have genome sizes of 816,394 bp (20) and 580,070 bp (12), respectively, with the latter considered the smallest self-replicating biological cell (14, 38). These bacterial pathogens possess terminal tip-like structures comprised of specific membrane adhesins and adherence-related accessory proteins that mediate surface parasitism of target cells (5) and are essential for virulence (4). While adherence of virulent M. pneumoniae is mediated primarily by tip organelle-associated adhesins (10, 24), the absence of these proteins in hemadsorption-negative mutants (HA⁻ class II mutants) (17) still permits detectable adherence (18), suggesting the involvement of alternative mechanisms by which mycoplasmas bind to host cells.Recently, we showed that M. pneumoniae surface-associated elongation factor Tu (EF-Tu_Mp; MPN665) and the pyruvate dehydrogenase E1 beta subunit (MPN392) interact with fibronectin (Fn) (11). In addition, we demonstrated that HA⁻ class II mutants also bind Fn through EF-Tu (11). Fn is an abundantly available pathogen target (22) that exists in soluble form in blood fluids and plasma and in fibrillar form in the extracellular matrix (56). M. pneumoniae could readily access the extracellular matrix through virulence-related determinants following epithelial cell damage (29) and could directly bind to subepithelial tissue targets through EF-Tu interactions with Fn. Furthermore, these distinct pathogenic pathways may also contribute to the ability of M. pneumoniae to invade and to establish intracellular and perinuclear residence (9, 57).Detailed analyses of EF-Tu_Mp-Fn interactions revealed the critical role of the carboxyl region of EF-Tu (amino acids 192 to 219 and 314 to 394) in Fn recognition (3). Other mycoplasmas with tip organelles, such as Mycoplasma penetrans and Mycoplasma gallisepticum, have been reported to bind Fn through a 65-kDa protein (13) and the PlpA and Hlp3 proteins (34).Following our initial findings of EF-Tu_Mp-Fn interactions, surface-associated EF-Tu proteins from other microorganisms, including Lactobacillus johnsonii, Listeria monocytogenes, and Pseudomonas aeruginosa, were reported to bind mucin (16), fibrinogen (43), plasminogen, and factor H (32). Since EF-Tu is one of the most highly conserved proteins in mycoplasmas, it has been used to create an EF-Tu sequence-based mycoplasma phylogeny tree. This allows the classification of the human pathogens, M. genitalium and M. pneumoniae, along with M. gallisepticum, a poultry pathogen, in the same group (28). M. pneumoniae is an established pathogen of the respiratory tract (54) but has also been isolated from the urogenital tract (15). M. genitalium, an emerging sexually transmitted disease pathogen (27, 51), has also been associated with respiratory (6) and joint (50) pathologies. It has been suggested that the tissue-specific tropisms and pathogenic mechanisms of these two mycoplasmas are determined by genetic distinctions between them (19). Most of the open reading frames proposed for M. genitalium are present in M. pneumoniae. Overall, M. pneumoniae and M. genitalium share 67.4% average identity at the amino acid level, while conserved housekeeping proteins exhibit 70 to 97% identity (19). Among the latter proteins, EF-Tu displays a high sequence identity (96%).In this study, we compared EF-Tu-Fn binding between M. pneumoniae and M. genitalium and discovered biological and biochemical differences that facilitated the identification of key amino acids responsible for these interactions. Such distinctions provide evidence of unique colonization capabilities of these bacteria.     

Immunological cross-reactivity of a Mycoplasma pneumoniae membrane-associated protein antigen with Mycoplasma genitalium and Acholeplasma laidlawii.

A murine monoclonal antibody, OC2F5, reacts with a Mycoplasma pneumoniae antigen with an approximate Mr of 43,000. This antigen is trypsin and proteinase K sensitive and partitions in the detergent phase of a Triton X-114 solution. The monoclonal antibody cross-reacts with an antigen from both Mycoplasma genitalium and Acholeplasma laidlawii with a similar molecular weight. This cross-reactivity should be considered in the development of M. pneumoniae antigen detection systems based on the use of antibodies directed to this protein antigen.     

Antigenic determinants of the attachment protein of Mycoplasma pneumoniae shared by other pathogenic Mycoplasma species.

In previous studies with hyperimmune rabbit antisera, we found evidence of serologic cross-reactivity among Mycoplasma pneumoniae, Mycoplasma genitalium, and Mycoplasma gallisepticum. Because of certain biologic and morphologic similarities of these species, attempts were made to determine if this cross-reactivity related to the attachment protein (P1) of M. pneumoniae. Monoclonal and monospecific antibodies against P1 were used to probe proteins of the other species by immunoblotting. One of the P1 monoclonal antibodies was reactive with a smaller protein of M. genitalium; rabbit antiserum raised by immunization with P1 excised from a sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel was found to react with a similar-sized protein of M. gallisepticum. These preliminary findings suggest antigenic sharing among the species examined; however, limitations of the methods used are discussed.     

Comparison of host responses after intranasal infection of guinea-pigs with Mycoplasma genitalium or with Mycoplasma pneumoniae

Guinea-pigs were infected intranasally with Mycoplasma genitalium or Mycoplasma pneumoniae. The lung lesions produced by the two mycoplasmas were comparable in extent and histological pattern. Sera of both animal groups taken 2 weeks after infection reacted strongly in the complement fixation test with the M. pneumoniae glycolipid extract. In an ELISA using the respective adherence proteins (P1-protein of M. pneumoniae and MgPa of M. genitalium), strong specific activity, but also considerable cross-reactions were found. Epitope analysis by using overlapping octapeptides of a P1-region immunologically active in human M. pneumoniae infections and of the corresponding MgPa-region revealed six common epitopes but also one M. genitalium and two M. pneumoniae specific determinants. For analysis of a possible pathogenicity of M. genitalium in the human respiratory tract species-specific tests have to be developed.     

Failure of Mycoplasma pneumoniae infection to confer protection against Mycoplasma genitalium: observations from a mouse model

Mycoplasma pneumoniae and M. genitalium are genomically distinct but share antigens that induce some serological cross-reactivity. Therefore, the possibility that M. pneumoniae infection of the human respiratory tract might provide immunity to M. genitalium infection of the genital tract was considered. Because of the difficulty of assessing this proposition in man, it was evaluated experimentally in a mouse model. Female BALB/c mice were susceptible to infection of the vagina with M. pneumoniae, whereas those infected previously in the oropharynx with M. pneumoniae were completely immune to infection of the vagina with this mycoplasma. However, all mice with such a respiratory tract infection were susceptible to infection of the vagina with M. genitalium. The findings suggest that an M. pneumoniae infection of the human respiratory tract is unlikely to influence infection of the genital tract by M. genitalium.     

The mature MgPa-adhesin of Mycoplasma genitalium

A high molecular weight protein of Mycoplasma genitalium (MgPa-protein) was isolated by fractionated solubilization with 1% CHAPS, followed by subsequent extraction with 2% octylglucoside and size exclusion chromatography. The comparison of the N-terminal sequence reported here with published nucleotide sequence data revealed the existence of a signal sequence; the molecular weight of the mature MgPa-protein was calculated to be 153, 134 dalton. The protein shares antigenic determinants with the adhesin of Mycoplasma pneumoniae (P1-protein). Therefore the amino acid sequence of the MgPa-protein was matched to the P1-protein sequence. Five of seven computer predicted hydrophobic regions of both amino acid sequences were located in corresponding regions.