Question

A) Indicate the function of the ABC transporter and what does the ABC means. B) How would the ABC transporter function on a gram negative bacteria that transports water soluble substrates such as amino-acids or peptides actively? Describe with each of the substrates and use a diagram to demonstrate both.

Answer 1

Answer-a) ATP-binding cassette or ABC transporters are a large family of proteins that are found in all living organisms such as bacterias, archaea, and Eukaryotes. They translocate their substrates in outward direction i.e. from cytoplasmic to lumen side of membranes or in inner direction i.e from lumen side to the cytoplasmic side of membranes, they are referred as exporters and importers respectively. They utilize the energy of ATP binding and hydrolysis to transport substrates across the cellular membranes.

b) ABC transporters are responsible for transportation of lipopolysaccharides in gram negative bacteria. LPS is a major component of outer membrane of Gram negative bacteria. The ABC transporter i.e LolCDE, initiates the detachment of lipoproteins from the inner membrane that results in the formation of water soluble lipoprotein-LolA complex. These Lipoproteins are then transferred to LolB at the outer membrane and get incorporated into lipid bilayer.