Mycoplasmas: a distinct cytoskeleton for wall-less bacteria.

The bacterial genus Mycoplasma includes a large number of highly genomically-reduced species which in nature are associated with hosts either commensally or pathogenically. Several Mycoplasma species, including Mycoplasma pneumoniae, feature a multifunctional polar structure, the terminal organelle. Essential for colonization of the host and for gliding motility, the terminal organelle is associated with an internal cytoskeleton crucial to its assembly and function. This cytoskeleton is structurally and compositionally novel as compared with the cytoskeletons of other organisms, including other bacteria, is also involved in the cell division process. In this review we discuss the cytoskeletal structures and protein components of the attachment organelle and how they might interact and contribute to its various functions.