title: Mycoplasma pneumoniae J-domain protein required for terminal organelle function.
abstract: The cell wall-less prokaryote Mycoplasma pneumoniae causes tracheobronchitis and primary atypical pneumonia in humans. Colonization of the respiratory epithelium requires proper assembly of a complex, multifunctional, polar terminal organelle. Loss of a predicted J-domain protein also having domains unique to mycoplasma terminal organelle proteins (TopJ) resulted in a non-motile, adherence-deficient phenotype. J-domain proteins typically stimulate ATPase activity of Hsp70 chaperones to bind nascent peptides for proper folding, translocation or macromolecular assembly, or to resolve stress-induced protein aggregates. By Western immunoblotting all defined terminal organelle proteins examined except protein P24 remained at wild-type levels in the topJ mutant; previous studies established that P24 is required for normal initiation of terminal organelle formation. Nevertheless, terminal organelle proteins P1, P30, HMW1 and P41 failed to localize to a cell pole, and when evaluated quantitatively, P30 and HMW1 foci were undetectable in >40% of cells. Complementation of the topJ mutant with the recombinant wild-type topJ allele largely restored terminal organelle development, gliding motility and cytadherence. We propose that this J-domain protein, which localizes to the base of the terminal organelle in wild-type M. pneumoniae, functions in the late stages of assembly, positioning, or both, of nascent terminal organelles.
authors.affiliation: Department of Microbiology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Cloward
authors.forename: Duncan C
authors.initials: DC
authors.lastname: Krause
mesh_terms: D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016254:Mutagenesis, Insertional; D009154:Mutation; D009177:Mycoplasma pneumoniae / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D016366:Open Reading Frames; D009876:Operon; D015388:Organelles / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins