Structure and mode of action of microplusin, a copper II-chelating antimicrobial peptide from the cattle tick

Related Experiment Video

Updated: Jun 19, 2026

Purification of Biotinylated Cell Surface Proteins from Rhipicephalus microplus Epithelial Gut Cells
12:03

Purification of Biotinylated Cell Surface Proteins from Rhipicephalus microplus Epithelial Gut Cells

Published on: July 23, 2017

Fernanda D Silva1, Carlos A Rezende, Diego C P Rossi

  • 1Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-900 São Paulo, Brazil.

The Journal of Biological Chemistry
|October 16, 2009
PubMed

Insights

Microplusin, a tick antimicrobial peptide, exhibits bacteriostatic effects by binding copper II, inhibiting bacterial respiration. Its unique structure and copper sequestration mechanism offer new insights into innate immunity.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Microbiology

Background:

  • Microplusin is a novel antimicrobial peptide (AMP) from the tick Rhipicephalus (Boophilus) microplus.
  • It is a cysteine-rich AMP with histidine-rich termini, belonging to a new family of innate defense molecules.
  • AMPs are crucial in the defense against bacterial and fungal infections.

Purpose of the Study:

  • To determine the NMR solution structure of microplusin.
  • To investigate microplusin's metal-binding properties (copper II and iron II).
  • To elucidate the mode of action of microplusin against Gram-positive bacteria.

Main Methods:

  • Nuclear Magnetic Resonance (NMR) spectroscopy was used to determine the 3D structure and map metal-binding sites.
  • The antimicrobial activity of microplusin was tested against Micrococcus luteus.
  • Bacterial respiration and membrane permeability assays were performed.

Main Results:

  • Microplusin adopts a unique alpha-helical globular structure, distinct from other known AMPs.
  • The peptide binds copper II and iron II, with copper II binding mapped to a specific region.
  • Microplusin demonstrated a bacteriostatic effect on Micrococcus luteus without membrane permeabilization.
  • The bacteriostatic effect was reversible by copper II supplementation and linked to the inhibition of copper-dependent respiration.

Conclusions:

  • The unique structure of microplusin contributes to its novel antimicrobial mechanism.
  • Microplusin's antibacterial activity is primarily mediated by its ability to bind and sequester copper II.
  • This metal sequestration disrupts essential copper-dependent processes like bacterial respiration.

More Related Videos

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR14:44

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Published on: December 16, 2013

Production and Visualization of Bacterial Spheroplasts and Protoplasts to Characterize Antimicrobial Peptide Localization10:13

Production and Visualization of Bacterial Spheroplasts and Protoplasts to Characterize Antimicrobial Peptide Localization

Published on: August 11, 2018

Related Concept Videos

Inhibitors of Gram-positive Cell Wall Synthesis01:23

Inhibitors of Gram-positive Cell Wall Synthesis

Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
Antimicrobial Proteins01:23

Antimicrobial Proteins

Antimicrobial proteins are important components of the immune system. They aid the body in combating pathogens by either killing them directly or hindering their replication processes. Four main types of antimicrobial substances are interferons, the complement system, iron-binding proteins, and antimicrobial proteins.
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...
Inhibitors of Bacterial Protein Synthesis01:25

Inhibitors of Bacterial Protein Synthesis

Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...
Anthelminthic Agents01:15

Anthelminthic Agents

Anthelmintic drugs differ significantly from antiparasitic therapies targeting protozoa, primarily due to differences in parasite biology. Whereas most protozoal treatments act on proliferating cells, anthelmintics are typically directed against mature, nonproliferative helminths. The therapeutic approach considers the helminth's reliance on neuromuscular coordination, glucose metabolism, and microtubular integrity for survival, reproduction, and localization within the host. Most anthelmintics...
Clinical Significance of Antibiotic Resistance01:25

Clinical Significance of Antibiotic Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...