Trimeric autotransporter adhesin

Figure 1

Schematic diagram of the basic Trimeric Autotransporter Adhesin structure
Figure 2

The C-terminal membrane anchor domain can clearly be seen on the right in blue. The stalk domain can be seen in red.

In molecular biology, trimeric autotransporter adhesins (TAAs), are proteins found on the outer membrane of Gram-negative bacteria. Bacteria use TAAs in order to infect their host cells via a process called cell adhesion.[1] TAAs also go by another name, oligomeric coiled-coil adhesins, which is shortened to OCAs. In essence, they are virulence factors, factors that make the bacteria harmful and infective to the host organism.[2]

TAAs are just one of many methods bacteria use to infect their hosts, infection resulting in diseases such as pneumonia, sepsis, and meningitis. Most bacteria infect their host through a method named the secretion pathway. TAAs are part of the secretion pathway, to be more specific the type Vc secretion system.[3]

Trimeric autotransporter adhesins have a unique structure. The structure they hold is crucial to their function. They all appear to have a head-stalk-anchor structure. Each TAA is made up of three identical proteins, hence the name trimeric. Once the membrane anchor has been inserted into the outer membrane, the passenger domain passes through it into the host extracellular environment autonomously, hence the description of autotransporter. The head domain, once assembled, then adheres to an element of the host extracellular matrix, for example, collagen, fibronectin, etc.[2]

  1. ^ Szczesny P, Linke D, Ursinus A, Bär K, Schwarz H, Riess TM, et al. (2008). Ghosh P (ed.). "Structure of the head of the Bartonella adhesin BadA". PLOS Pathog. 4 (8): e1000119. doi:10.1371/journal.ppat.1000119. PMC 2483945. PMID 18688279.
  2. ^ a b Linke D, Riess T, Autenrieth IB, Lupas A, Kempf VA (2006). "Trimeric autotransporter adhesins: variable structure, common function". Trends Microbiol. 14 (6): 264–70. doi:10.1016/j.tim.2006.04.005. PMID 16678419.
  3. ^ Mikula KM, Leo JC, Łyskowski A, Kedracka-Krok S, Pirog A, Goldman A (2012). "The translocation domain in trimeric autotransporter adhesins is necessary and sufficient for trimerization and autotransportation". J Bacteriol. 194 (4): 827–38. doi:10.1128/JB.05322-11. PMC 3272944. PMID 22155776.