Related Experiment Video

Updated: Feb 4, 2026

Quantifying Yersinia pseudotuberculosis Type III Secretion System Activity Following Iron Starvation and Anaerobic Growth
08:36

Quantifying Yersinia pseudotuberculosis Type III Secretion System Activity Following Iron Starvation and Anaerobic Growth

Published on: May 31, 2024

905

Ail provides multiple mechanisms of serum resistance to Yersinia pestis

Joshua J Thomson1, Sarah C Plecha1, Eric S Krukonis1,2,3

  • 1Division of Integrated Biomedical Sciences, University of Detroit Mercy School of Dentistry, Detroit, MI, USA.

Molecular Microbiology
|September 28, 2018
PubMed

Insights

Yersinia pestis Ail protein helps bacteria survive in the blood by evading the complement system. Specific mutations in Ail protein reveal a novel mechanism of serum resistance crucial for plague infections.

Area of Science:

  • Microbiology
  • Immunology
  • Structural Biology

Background:

  • Ail is an outer membrane protein of Yersinia pestis essential for survival during septicemic plague.
  • Complement resistance is critical for Y. pestis survival, and bacteria evade it by recruiting complement regulatory factors.
  • Y. pestis Ail interacts with complement regulatory factors like vitronectin (Vn) and C4b-binding protein (C4BP).

Purpose of the Study:

  • To investigate the role of specific amino acids in Y. pestis Ail's interaction with complement regulatory proteins.
  • To elucidate the mechanism of serum resistance conferred by Ail, beyond its interaction with regulatory factors.
  • To understand Ail's complement evasion strategies at bacterial concentrations relevant to early plague infection.

Main Methods:

  • Co-sedimentation assays to study protein interactions.
  • Site-directed mutagenesis to alter specific amino acids (F80A, F130A) in Ail.
  • Serum resistance assays comparing wild-type, mutant, and deleted strains.
  • Analysis of C9 polymerization and MAC assembly.

Main Results:

  • Amino acids F80 and F130 of Y. pestis Ail are critical for binding Vn, factor H, and C4BP.
  • Ail mutants lacking interaction with these factors still exhibit significantly enhanced serum resistance (10,000-fold).
  • Mutant Ail prevents C9 polymerization and MAC assembly, indicating a direct interference mechanism.
  • At physiological concentrations, Ail shows weak Vn recruitment and no factor H recruitment.

Conclusions:

  • Y. pestis Ail employs a dual mechanism for complement evasion: recruitment of regulatory proteins and direct interference with MAC assembly.
  • The direct interference mechanism is independent of Vn, factor H, and C4BP binding.
  • This alternative serum resistance mechanism is likely vital during the early stages of septicemic plague.

More Related Videos

Assays for Studying the Role of Vitronectin in Bacterial Adhesion and Serum Resistance10:55

Assays for Studying the Role of Vitronectin in Bacterial Adhesion and Serum Resistance

Published on: October 16, 2018

8.6K
Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example06:52

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

Published on: June 19, 2011

14.2K

Related Concept Videos

Resistivity01:22

Resistivity

When a voltage is applied to a conductor, an electrical field is generated, and charges in the conductor feel the force due to the electrical field. The current density that results depends on the electrical field and the properties of the material. In some materials, including metals at a given temperature, the current density is approximately proportional to the electrical field. In these cases, the current density can be modeled as:
4.6K
Resistance01:19

Resistance

When a current moves through any conductor, the conductor causes some level of difficulty for the current to flow. The measure of that difficulty is known as the resistance of the material and is represented by R. Every material has its own resistance. In the case of conductors, heat is emitted whenever a current passes through them. Resistance depends on the resistivity of the material. Resistivity is a characteristic of the material used to fabricate electrical components, whereas the...
6.0K
Reaction Mechanisms03:06

Reaction Mechanisms

Chemical reactions often occur in a stepwise fashion, involving two or more distinct reactions taking place in a sequence. A balanced equation indicates the reacting species and the product species, but it reveals no details about how the reaction occurs at the molecular level. The reaction mechanism (or reaction path) provides details regarding the precise, step-by-step process by which a reaction occurs.
For instance, the decomposition of ozone appears to follow a mechanism with two steps:
30.9K
Multiple Allele Traits01:49

Multiple Allele Traits

The Concept of Multiple Allelism
38.1K
Equivalent Resistance01:16

Equivalent Resistance

In circuit analysis, situations often arise where resistors are neither in series nor parallel configurations. To tackle such scenarios, three-terminal equivalent networks like the wye (Y) (Figure 1 (a)) or tee (T) and delta (Δ) (Figure 1 (b)) or pi (π) networks come into play. These networks offer versatile solutions and are frequently encountered in various applications, including three-phase electrical systems, electrical filters, and matching networks.
985
Resistance and Conductance01:25

Resistance and Conductance

A conductor's DC resistance at a given temperature is influenced by its resistivity, length, and cross-sectional area. Resistivity is an inherent property of the conductor material, with annealed copper serving as the international standard for measurement. For instance, the resistivity of hard-drawn aluminum at 20 degrees Celsius is 61% of the standard conductivity of annealed copper.
Various factors impact the resistance of a conductor. Spiraling in stranded conductors increases their...
517