biology

YadA bacterial adhesin protein domain

YadA bacterial adhesin protein domain is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand YadA bacterial adhesin protein domain rather than just read about it. In short: In molecular biology, YadA is a protein domain which is short for Yersinia adhesin A. These proteins have strong sequence and structural homology, particularly at their C-terminal end.

Key takeaways

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Reference excerpt

In molecular biology, YadA is a protein domain which is short for Yersinia adhesin A. These proteins have strong sequence and structural homology, particularly at their C-terminal end. The function is to promote their pathogenicity and virulence in host cells, though cell adhesion. YadA is found in three pathogenic species of Yersinia, Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica. The YadA domain is encoded for by a virulence plasmid in Yersinia, which encodes a type-III secretion (T3S) system consisting of the Ysc injectisome and the Yop effectors.

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. Furthermore, YadA expression is mainly temperature regulated, at 37 degrees Celsius. It also has two molecular regulators: an activator, VirF and a repressor, YmoA.

Substrate adhesion The YadA protein domain adheres to the following substrates:

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.

Structure

C-terminal domain structure The C-terminal region is a transmembrane region which consists of 4 beta strands which form trimers in the outer membrane. The C-terminal contains 9 amino acids which alternate hydrophobic amino acids ending in F (Phenylalanine) or W (Tryptophan), this composes a targeting motif for the outer membrane of the Gram-negative cell membrane. This region is important for oligomerisation. 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 C-terminal membrane anchor, an 18 nm long coiled-coil stem and a 5 nm long N-terminal globular head structure consisting of a left-handed parallel beta roll. YadA is an example of an oligomeric coiled-coil adhesion (Oca). The Oca protein families are a subset of autotransporters, also known as the type Vc or trimeric autotransporters. Trimerization is thought to involve the coiled-coil stem and the C-terminal membrane anchor, which forms a 12-strand 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.

History YadA, an adhesin from Yersinia, was the first member of this family to be characterised. UspA2 from Moraxella was second. The Eib immunoglobulin-binding proteins from Escherichia coli were third, followed by the DsrA proteins of Haemophilus ducreyi, amongst others.

See also Trimeric Autotransporter Adhesins (TAA)

References

Illustrations

Worked examples

Example 1 — a first encounter with YadA bacterial adhesin protein domain

Start with the simplest possible case. Write down what YadA bacterial adhesin protein domain claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to YadA bacterial adhesin protein domain before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about YadA bacterial adhesin protein domain ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of YadA bacterial adhesin protein domain

In research: YadA bacterial adhesin protein domain appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses YadA bacterial adhesin protein domain in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: YadA bacterial adhesin protein domain is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bacterial proteins, Protein domains, Protein families, so understanding it makes those chapters shorter.
In everyday life: Look for YadA bacterial adhesin protein domain outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

What is YadA bacterial adhesin protein domain in simple terms?

In molecular biology, YadA is a protein domain which is short for Yersinia adhesin A. These proteins have strong sequence and structural homology, particularly at their C-terminal end.

Why does YadA bacterial adhesin protein domain matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study YadA bacterial adhesin protein domain?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

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