Bacterial secretion systems

Question 1

secretion systems for virulence factors

Answer 1

• pathogens use dedicated secretion systems to transport virulence factors across the bacterial cell membrane
• these secretion systems can be divided into classes based on structure, function and specificity

Question 2

secretion systems - generic pathways

Answer 2

most common secretion pathways

• secretion (sec) - a means to export unfolded proteins into or through the plasma membrane
• twin arginine translocation - a means to actively transport folded protein across the plasma membrane

Question 3

Sec dependent pathway

Answer 3

• chaperone protein (SecB) binds to protein, guides to transport machinery
• protein released, binds to SecA
• SecA translocates the protein through the membrane using the SecYEG channel

Question 4

Tat pathway

Answer 4

• prior to transport, proteins are folded
• folded protein is recognised by TatB (not present on gran positive bacteria), and TatC and delivered to TatA,
• TatA forms a channel through which the protein can travel across the membrane