YadA bacterial adhesin protein domain

Available protein structures:
Pfam	structures / ECOD
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

YadA bacterial adhesin protein domain
YadA bacterial adhesin protein domain
	The beta barrel structure found in the C-terminus of the bacterial adhesin protein domain, YadA [1]
Identifiers
Symbol	YadA
Pfam	PF03895
Pfam clan	CL0327
InterPro	IPR005594
Pfam
Available protein structures:
Pfam	structures / ECOD
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

In molecular biology, YadA is a

type-III secretion

(T3S) system consisting of the Ysc injectisome and the Yop effectors.^[1]

Function

Essentially, the main function of the YadA domain is to help cell adhesion and to increase virulence. YadA is a collagen-binding outer membrane protein. It forms the fibrillar matrix on the bacterial cell surface. This aids cell attachment and helps the bacteria invade eukaryotic cells. Additionally, by forming the fibrillar matrix, the YadA domain protects the bacteria by facilitating agglutination resistance, serum resistance, complement inactivation and phagocytosis resistance.

The importance of adhesins to YadA function and Yersinia survival is huge. Attachment further allows more interactions and increase of biofilm formation to aid bacterial colonization. In Yersinia, it helps initiate the infectious process in host cells and are critical virulence factors. Additionally, bacteria have the ability to regulate adhesion expression, meaning that when Yersinia no longer requires YadA, it can be turned off.^[2] Furthermore, YadA expression is mainly temperature regulated, at 37 degrees Celsius. It also has two molecular regulators: an activator, VirF and a repressor, YmoA.^[3]

Substrate adhesion

The YadA protein domain adheres to the following substrates:^[1]

epithelial cells
extracellular matrix
collagen
cellular fibronectin
laminin

Protein domains in YadA

C terminal domain

The

C-terminal domain consists of 120 amino acids which belong to a family of surface-exposed bacterial proteins. The YadA C-terminal domain has a particular function in translocating the trimeric N-terminal passenger domain to the exterior of the membrane and is also responsible for trimerisation.^[4]

Structure

C-terminal domain structure

The C-terminal region is a

oligomerisation.^[6]

The C-terminal domain helps to build the beta barrel pore in the outer membrane.

YadA protein structure

YadA is a homotrimeric outer membrane protein which forms part of the fibrillar matrix. Simplistically, this means the protein is made of three of the same subunits, on the outer surface of the membrane. The surface is entirely covered in the YadA lollipop structures. made of a short

autotransporters, also known as the type Vc or trimeric autotransporters.^[1]

Trimerization is thought to involve the

beta-barrelfrom the four transmembrane beta-strands

of the three monomers. This beta-barrel would form a pore-like structure through which the N-terminal head and coiled helical domains of the three monomer chains exit to the cell surface. The YadA protein domain, is a form of trimeric autotransporter adhesins (TAAs). Each TAA must consist of a head, stalk and a

beta-barrel membrane anchor.^[7]