Structure, function, and assembly of the terminal organelle of Mycoplasma pneumoniae

Abstract

Mycoplasmas are cell wall-less bacteria at the low extreme in genome size in the known prokaryote world, and the minimal nature of their genomes is clearly reflected in their metabolic and regulatory austerity. Despite this apparent simplicity, certain species such as Mycoplasma pneumoniae possess a complex terminal organelle that functions in cytadherence, gliding motility, and cell division. The attachment organelle is a membrane-bound extension of the cell and is characterized by an electron-dense core that is part of the mycoplasma cytoskeleton, defined here for working purposes as the protein fraction that remains after extraction with the detergent Triton X-100. This review focuses on the architecture and assembly of the terminal organelle of M. pneumoniae. Characterizing the downstream consequences of defects involving attachment organelle components has made it possible to begin to elucidate the probable sequence of certain events in the biogenesis of this structure. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.

Force and Velocity of Mycoplasma mobile Gliding

“…The protein molecule has an extracellular domain with at least one transmembrane domain near its N terminus. M. pneumoniae, a human pathogen, also has a polarized cell morphology, and it also glides in the direction of its attachment organelle (19,22). The gliding mechanism of M. pneumoniae is believed to be similar to that of M. mobile, although the speed is 10 times slower (19).…”

“…Mycoplasmas do not have any appendages such as flagella or pili (19) or any genes obviously related to motility, including motor proteins such as myosin or kinesin (7, 10, 13). However, a transmembrane protein associated with a cytoskeleton-like structure has been shown to be necessary for glass binding in Mycoplasma pneumoniae (22).Mycoplasma mobile, isolated from a fish gill organ, has a conical cell structure, with the attachment organelle at the apex of the cone. It glides up to four cell lengths per second (2.5 m/s) in the direction of the apex, which is designated as a head-like structure (30).…”

“…Mycoplasmas do not have any appendages such as flagella or pili (19) or any genes obviously related to motility, including motor proteins such as myosin or kinesin (7,10,13). However, a transmembrane protein associated with a cytoskeleton-like structure has been shown to be necessary for glass binding in Mycoplasma pneumoniae (22).…”

First identification of proteins involved in motility of Mycoplasma gallisepticum

“…Formation of the TO appears to be a complex process that has to be well orchestrated, chronologically and spatially [14]. The TO of M. pneumoniae consists of a network of cytadherence proteins, including P1, P30, the accessory proteins P65, B, C, and the structural proteins HMW1, HMW2, and HMW3 [15].…”

Inhibition of message for FcεRI α chain blocks mast cell IL-4 production induced by co-culture with Mycoplasma pneumoniae

“…One member of a complex of proteins concentrated there, the 170 kDa P1 adhesin, plays a major role in the attachment of M. pneumoniae to host cells [16]. Reduced P1 expression at the adhesive tip in mutant bacterial strains or blockade of P1 using monoclonal antibodies results in reduced adherence [17][18][19].…”