Localization of the Mycoplasma pneumoniae cytadherence-accessory proteins HMW1 and HMW4 in the cytoskeletonlike Triton shell.
The location of the cytadherence-accessory high-molecular weight proteins 1 and 4 (HMW1/4) within Mycoplasma pneumoniae cells has been studied by both biochemical and electron microscopic techniques. Peptide mapping studies demonstrated that HMW1/4 share almost identical peptide profiles, suggesting that the two proteins are structurally related. Examination of thin sections of M. pneumoniae with antibodies to HMW1/4 and colloidal gold particles revealed distinct labeling of the filamentous extensions of the mycoplasma cells. Labeling was absent on thin sections of a cytadherence-deficient variant lacking HMW1/4. HMW1/4 partitioned in the detergent-insoluble fraction following Triton X-100 extraction, and analysis by sucrose density gradient centrifugation suggested that HMW1/4 are part of a high-molecular-weight, multiprotein complex. These results were confirmed by immunogold labeling of Triton X-100-extracted M. pneumoniae cells incubated with antibodies to HMW1/4: gold particles bound in specific clusters to detergent-insoluble filaments. Finally, immunogold labeling of whole cells revealed that HMW1/4 are exposed on the cell surface, although to a lesser degree than on the cell interior. These findings indicate that HMW1/4 are membrane proteins associated with the cytoskeletonlike triton shell of M. pneumoniae and localized primarily in the filamentous extensions of the mycoplasma cells.
Stevens
M K
MK
Department of Microbiology, University of Georgia, Athens 30602.
Krause
D C
DC
D000907:Antibodies, Bacterial; D000918:Antibody Specificity; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000032:analysis* / Q000276:immunology; D015153:Blotting, Western; D003599:Cytoskeleton / Q000737:chemistry; D003902:Detergents; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000032:analysis / Q000276:immunology; D008855:Microscopy, Electron, Scanning; D016253:Microscopy, Immunoelectron; D009177:Mycoplasma pneumoniae / Q000032:analysis* / Q000276:immunology / Q000648:ultrastructure; D017830:Octoxynol; D010449:Peptide Mapping; D011092:Polyethylene Glycols
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D003902:Detergents; D008565:Membrane Proteins; D011092:Polyethylene Glycols; D017830:Octoxynol