Bacterial type IV secretions systems move DNA and proteins out of a cell. Usually transfer of this DNA/proteins requires cell-to-cell contact, however one type of T4SS releases DNA from the extracellular milieu. [1]
GENERAL STRUCTURE FEATURES OF TYPE 4 SECRETION SYSTEMS
With different functions comes many variations on the structure of T4SS, however the most well understood set of structures were studied through the Gram-negative bacteria A. tumefaciens. It is called the VirB/VirD4 system[2].
VirB is made up of 11 different VirB proteins systhesized from the virB operon. Most T4SS have homologes of these 12 proteins (11 from VirB and 1 from VirD)
Overview of T4SS structures
[1]
VirB7, VirB7 and VirB10 initiate the assembly of the core of the T4SS. The complex forms spontaneously with out the input of external energy like ATP.
Overview of formation of T4SS
[1]
