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)
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]
Overview of T4SS structures
[1]
