page_title: Trimeric autotransporter adhesin
section_title: N-terminal head domain
hierarchical_section_title: Trimeric autotransporter adhesin / N-terminal head domain
caption_attribution_description: English: Comparison of Trimeric Autotransporter Adhesin Head Domains
context_page_description: In molecular biology, trimeric autotransporter adhesins, 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. 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.
  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.
  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.
context_section_description: Structure: This particular domain is a trimer of single-stranded, left-handed beta-helices. These associate to form a nine-coiled left-handed beta-roll. It contains sequence motifs, of which there is a strong similarity with other TAA heads. This indicates that there is a lot of similarity when comparing protein structure. The head domain is connected to the stalk by a short, highly conserved sequence, which is often called the neck, or occasionally named the connector.
  Function: The function of this protein domain is to bind to the extracellular matrix of the host, most notably fibronectin, collagen, and laminin. The head domain is very important for attachment to the host cell and for autoagglutination, sticking to itself.
  There are several types of head domain. Each domain helps the head to bind to a different component of the extracellular matrix. These are as follows: YadA-like head domain, Trp-ring, GIN, FxG, HIN1, and HIN2. This entry focuses on the first three mentioned.
caption: Figure 4
  Comparison of Head domains in different Trimeric Autotransporter Adhesins[10] (Figure used from open access journal, in the public domain, Public Library of Science (PLoS) Pathogen)
exif: {}