Molecular Characterization of Mycoplasma arthritidis Variable Surface Protein MAA2

Abstract

Earlier studies implied a role for Mycoplasma arthritidis surface protein MAA2 in cytadherence and virulence and showed that it exhibited both size and phase variability. Here we report the further analysis of MAA2 and the cloning and sequencing of the maa2 gene from two M. arthritidis strains, 158p10p9 and H606, expressing two size variants of MAA2. Triton X-114 partitioning and metabolic labeling with [3H]palmitic acid suggested lipid modification of MAA2. Surface exposure of the C terminus was indicated by cleavage of monoclonal antibody-specific epitopes from intact cells by carboxypeptidase Y. The maa2genes from both strains were highly conserved, consisting largely of six (for 158p10p9) or five (for H606) nearly identical, 264-bp tandem direct repeats. The deduced amino acid sequence predicted a largely hydrophilic, highly basic protein with a 29-amino-acid lipoprotein signal peptide. The maa2 gene was expressed inEscherichia coli from the lacZ promoter of vector pGEM-T. The recombinant product was approximately 3 kDa larger than the native protein, suggesting that the signal peptide was not processed in E. coli. The maa2 gene and upstream DNA sequences were cloned from M. arthritidisclonal variants differing in MAA2 expression state. Expression state correlated with the length of a poly(T) tract just upstream of a putative −10 box. Full-sized recombinant MAA2 was expressed inE. coli from genes derived from both ON and OFF expression variants, indicating that control of expression did not include alterations within the coding region.

Mycoplasma superantigen initiates a TLR4-dependent Th17 cascade that enhances arthritis after blocking B7-1 inMycoplasma arthritidis-infected mice

“…Clearly other signalling pathways and components of live mycoplasmas are playing a role in immune responses and disease outcomes in mice infected with M. arthritidis . In this context, we note that M. arthritidis possesses a number of pathogenic components such as adhesins (MAA1 and MAA2) (Washburn et al ., 1998; 2000) which aid the organisms to attach to host cells and a bacteriophage that has variously been associated with organism virulence (Voelker et al ., ; Clapper et al ., ). In addition, a family of lipoproteins have been identified by us which possess TLR2‐dependent macrophage‐activating properties and which induce a pro‐inflammatory cytokine response after in vivo administration (Hasebe et al ., ).…”

Phase‐locked mutants of Mycoplasma agalactiae: defining the molecular switch of high‐frequency Vpma antigenic variation

“…Such homo- or heteropolymeric tracts are known to undergo frequent and reversible changes in the number of nucleotides via slipped-strand mispairing and lead to variation of cell surface proteins in many mycoplasma species ( Citti et al ., 2005 ). For instance, the insertion or deletion of nucleotides in the spacer region between the −35 and −10 region has been shown to turn ON or OFF the transcription of the vlp , maa2 and vmm genes of Mycoplasma hyorhinis , Mycoplasma arthritidis and Mycoplasma mycoides respectively ( Citti and Wise, 1995 ; Washburn et al ., 1998 ; Persson et al ., 2002 ). Although site-specific DNA recombination has been proposed as the mechanism underlying Vpma phase variation ( Glew et al ., 2002 ), slipped-strand mispairing might also be operational in M. agalactiae and provide it with another mode of eliciting surface diversity by turning ON or OFF the single promoter present in the vpma locus.…”

Differential Posttranslational Processing Confers Intraspecies Variation of a Major Surface Lipoprotein and a Macrophage-Activating Lipopeptide ofMycoplasma fermentans

“…Lipid-modified translation products expressed on the surface of mycoplasmas are increasingly recognized as an important class of proteins contributing to fundamental biological and pathogenic processes of these organisms, including adaptive surface variation now widely observed in this group of wall-less procaryotes (3,4,28,61) and modification of assorted host cell functions, characteristic of bacterial modulins (20). First, surface lipoproteins representing abundant mycoplasma coat proteins (4,27,50,66), adhesins (5,16,55,57,65), and transporters (52) have been shown to undergo rapid, heritable alteration in expression (phase variation) or structure, due to underlying mutational instabilities directly associated with corresponding genes. Genes encoding products with these diverse functions can occur in single copy or as families of related sequences distributed in the limited genome of these organisms.…”