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Home / Equine Research Bank / Biochem J / A novel horse alpha-defensin: gene transcription, recombinan...
The Biochemical journal2007; 407(2); 267-276; doi: 10.1042/BJ20070747

A novel horse alpha-defensin: gene transcription, recombinant expression and characterization of the structure and function.

Abstract: Defensins are a predominant class of antimicrobial peptides, which act as endogenous antibiotics. Defensins are classified into three distinct sub-families: theta-, beta-, and alpha-defensins. Synthesis of alpha-defensin has been confirmed only in primates and glires to date and is presumably unique for a few tissues, including neutrophils and Paneth cells of the small intestine. Antimicrobial activities of these peptides were shown against a wide variety of microbes including bacteria, fungi, viruses and protozoan parasites. In the present study, we report the characterization of the equine alpha-defensin DEFA (defensin alpha) 1. Transcription analysis revealed that the transcript of the gene is present in the small intestine only. An alignment with known alpha-defensins from primates and glires displayed a homology with Paneth-cell-specific alpha-defensins. DEFA1 was recombinantly expressed in Escherichia coli and subsequently analysed structurally by CD and molecular modelling. To examine the antimicrobial properties, a radial diffusion assay was performed with 12 different micro-organisms and the LD90 (lethal dose killing > or =90% of target organism) and MBC (minimal bactericidal concentration) values were examined. DEFA1 showed an antimicrobial activity against different Gram-positive and Gram-negative bacteria and against the yeast Candida albicans. Using viable bacteria in combination with a membrane-impermeable fluorescent dye, as well as depolarization of liposomes as a minimalistic system, it became evident that membrane permeabilization is at least an essential part of the peptide's mode of action.
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Publication Date: 2007-07-11 PubMed ID: 17620056PubMed Central: PMC2049026DOI: 10.1042/BJ20070747Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article discusses the discovery and characterization of a new alpha-defensin, a type of antimicrobial peptide, found in horses. The research further analyzed its structure and function, demonstrating its antimicrobial properties against a broad range of microorganisms.

Introduction to Defensins

  • Defensins are a class of antimicrobial peptides that act as natural antibiotics within the body.
  • They’re divided into three subfamilies: theta-, beta-, and alpha-defensins.
  • Alpha-defensins, previously only known in primates and the rodent family (glires), are typically found in certain tissues like neutrophils and Paneth cells in the small intestine.
  • They have shown antimicrobial activities against numerous microbes such as bacteria, fungi, viruses, and protozoan parasites.

Discovery and Characterization of Equine Alpha-Defensin

  • The study reports the discovery and characterization of an alpha-defensin (DEFA1) in horses.
  • Transcription analysis confirmed the presence of this gene only in the horse’s small intestine.
  • A comparison with known alpha-defensins from primates and glires revealed a similar homology with Paneth-cell-specific alpha-defensins.

Structural Analysis and Recombinant Expression

  • The equine DEFA1 was recombinantly expressed in Escherichia coli, a common bacteria used in gene expression studies.
  • Later, it was analyzed structurally using Circular Dichroism (CD) and molecular modelling, two standard methods used to understand protein structure.

Antimicrobial Properties of Equine DEFA1

  • The study demonstrated the antimicrobial activity of the newly discovered horse alpha-defensin. This peptide showed activity against various Gram-positive and Gram-negative bacteria and the yeast Candida albicans.
  • To explore its mechanism of action, they used a membrane-impermeable fluorescent dye along with live bacteria and discovered that membrane permeabilization (disruption of the cell membrane) is a crucial part of DEFA1’s antimicrobial activity.
  • They also found the LD90 (dose needed to kill >=90% of the target organism) and minimal bactericidal concentration (MBC) values by performing a radial diffusion assay against 12 different microorganisms.

Conclusion

  • The findings from this study suggest that the newly discovered horse alpha-defensin could be a potent tool in the fight against various infectious microorganisms, shedding new light on our understanding of the natural antimicrobial mechanisms found in animals.

Cite This Article

APA
Bruhn O, Regenhard P, Michalek M, Paul S, Gelhaus C, Jung S, Thaller G, Podschun R, Leippe M, Grötzinger J, Kalm E. (2007). A novel horse alpha-defensin: gene transcription, recombinant expression and characterization of the structure and function. Biochem J, 407(2), 267-276. https://doi.org/10.1042/BJ20070747

Publication

The Biochemical journal
ISSN: 1470-8728
NlmUniqueID: 2984726R
Country: England
Language: English
Volume: 407
Issue: 2
Pages: 267-276

Researcher Affiliations

Bruhn, Oliver
  • Institute of Animal Breeding and Husbandry, University of Kiel, Hermann-Rodewald-Strasse 6, 24118 Kiel, Germany.
Regenhard, Petra
    Michalek, Matthias
      Paul, Sven
        Gelhaus, Christoph
          Jung, Sascha
            Thaller, Georg
              Podschun, Rainer
                Leippe, Matthias
                  Grötzinger, Joachim
                    Kalm, Ernst

                      MeSH Terms

                      • Animals
                      • Bacteria
                      • Candida albicans
                      • Cell Membrane Permeability
                      • Circular Dichroism
                      • Cloning, Molecular / methods
                      • Horses
                      • Intestine, Small / chemistry
                      • Microbial Sensitivity Tests
                      • Models, Molecular
                      • Protein Conformation
                      • Tissue Distribution
                      • Transcription, Genetic
                      • alpha-Defensins / analysis
                      • alpha-Defensins / chemistry
                      • alpha-Defensins / genetics
                      • alpha-Defensins / immunology

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                      Citations

                      This article has been cited 8 times.
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