Probing the role of Proline in the antimicrobial activity and lipopolysaccharide binding of indolicidin

Swapna Bera, Anirban Ghosh, Shruti Sharma, Tanmoy Debnath, Banabihari Giri, Anirban Bhunia

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Hypothesis: Indolicidin (ILPWKWPWWPWRR-NH2), an antimicrobial peptide from bovine neutrophils, possesses significant antibacterial activity. An interesting feature of indolicidin is its unusually high content of Tryptophan and Proline residues. While the involvement of Tryptophan has been studied for its hemolytic and antibacterial activity, little is known about the roles played by Proline in these aspects. We herein investigate the structure and biological activities of indolicidin, where Proline at either one or more of the 3rd, 7th, 10th positions has been replaced by Alanine to better understand its structure and biological function. Experiments: Structural aspects of Proline residues of indolicidin and its effect on antimicrobial activity were elucidated by replacing Proline residues with Alanine. Minimum inhibitory concentration (MIC) and scanning electron microscopy (SEM) experiments provide substantial evidence for the importance of Proline residues for antimicrobial activity and cell wall disintegration. Binding affinity of the peptides to Lipopolysaccharide (LPS) was investigated using fluorescence spectroscopy and dynamic light scattering (DLS) in conjunction with 31PNMR spectroscopy and confirmed the disintegration of LPS layer. Findings: Our study reveals that Proline residues are necessary for interaction of indolicidin with LPS and establishes the significance of the third and tenth Proline residues for its antimicrobial activity. We believe that the presence of so many Proline residues provides the molecule a selective advantage of adopting different conformations varying from a globular, closed conformation to an open extended conformation, and even to a wedge-shaped conformation, which account for the diverse mechanisms of action of indolicidin.

Original languageEnglish (US)
Pages (from-to)148-159
Number of pages12
JournalJournal of Colloid and Interface Science
Volume452
DOIs
StatePublished - Aug 5 2015

Fingerprint

Proline
Lipopolysaccharides
Conformations
Disintegration
Peptides
Fluorescence spectroscopy
Dynamic light scattering
Bioactivity
Tryptophan
Alanine
Experiments
Cells
Spectroscopy
Scanning electron microscopy
Molecules
indolicidin

Keywords

  • <sup>31</sup>P NMR spectroscopy
  • AMP
  • CD spectroscopy
  • DLS
  • Indolicidin
  • LPS
  • SEM

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

Cite this

Probing the role of Proline in the antimicrobial activity and lipopolysaccharide binding of indolicidin. / Bera, Swapna; Ghosh, Anirban; Sharma, Shruti; Debnath, Tanmoy; Giri, Banabihari; Bhunia, Anirban.

In: Journal of Colloid and Interface Science, Vol. 452, 05.08.2015, p. 148-159.

Research output: Contribution to journalArticle

Bera, Swapna ; Ghosh, Anirban ; Sharma, Shruti ; Debnath, Tanmoy ; Giri, Banabihari ; Bhunia, Anirban. / Probing the role of Proline in the antimicrobial activity and lipopolysaccharide binding of indolicidin. In: Journal of Colloid and Interface Science. 2015 ; Vol. 452. pp. 148-159.
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AU - Giri, Banabihari

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AB - Hypothesis: Indolicidin (ILPWKWPWWPWRR-NH2), an antimicrobial peptide from bovine neutrophils, possesses significant antibacterial activity. An interesting feature of indolicidin is its unusually high content of Tryptophan and Proline residues. While the involvement of Tryptophan has been studied for its hemolytic and antibacterial activity, little is known about the roles played by Proline in these aspects. We herein investigate the structure and biological activities of indolicidin, where Proline at either one or more of the 3rd, 7th, 10th positions has been replaced by Alanine to better understand its structure and biological function. Experiments: Structural aspects of Proline residues of indolicidin and its effect on antimicrobial activity were elucidated by replacing Proline residues with Alanine. Minimum inhibitory concentration (MIC) and scanning electron microscopy (SEM) experiments provide substantial evidence for the importance of Proline residues for antimicrobial activity and cell wall disintegration. Binding affinity of the peptides to Lipopolysaccharide (LPS) was investigated using fluorescence spectroscopy and dynamic light scattering (DLS) in conjunction with 31PNMR spectroscopy and confirmed the disintegration of LPS layer. Findings: Our study reveals that Proline residues are necessary for interaction of indolicidin with LPS and establishes the significance of the third and tenth Proline residues for its antimicrobial activity. We believe that the presence of so many Proline residues provides the molecule a selective advantage of adopting different conformations varying from a globular, closed conformation to an open extended conformation, and even to a wedge-shaped conformation, which account for the diverse mechanisms of action of indolicidin.

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