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Matrix-assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) Mass Spectrometric Analysis of Intact Proteins Larger than 100 kDa
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Matrix-assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) Mass Spectrometric Analysis of Intact Proteins Larger than 100 kDa

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Identification and imaging of peptides and proteins on Enterococcus faecalis biofilms by matrix assisted laser

Melvin Blaze M T1, Berdan Aydin, Ross P Carlson

  • 1Department of Chemistry, MC 111, University of Illinois at Chicago, Chicago, IL 60607-7061, USA.

The Analyst
|September 11, 2012
PubMed

Insights

Researchers discovered the heptapeptide ARHPHPH in Enterococcus faecalis biofilms, originating from κ-casein. This peptide was localized to the E. faecalis side of mixed biofilms, highlighting a novel method for biofilm peptide and protein discovery.

Area of Science:

  • Microbiology
  • Proteomics
  • Biofilm Research

Background:

  • Enterococcus faecalis forms biofilms, which are complex microbial communities.
  • Understanding the molecular composition of biofilms is crucial for developing targeted interventions.
  • Previous studies have focused on planktonic bacteria, with less known about intact biofilm structures.

Purpose of the Study:

  • To identify and spatially localize peptides and proteins within intact Enterococcus faecalis biofilms.
  • To investigate the origin and localization of the heptapeptide ARHPHPH.
  • To demonstrate a novel proteomic approach for biofilm analysis.

Main Methods:

  • Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) for peptide and protein identification.
  • Top-down and bottom-up proteomic strategies combined for comprehensive analysis.
  • Coculture of E. faecalis and Escherichia coli biofilms to study interspecies interactions.
  • MALDI-MS imaging to determine spatial distribution of molecules within biofilms.

Main Results:

  • The heptapeptide ARHPHPH was identified in E. faecalis (V583 and ATCC 29212) biofilms and planktonic cultures.
  • ARHPHPH was localized to the E. faecalis side at the boundary of cocultured biofilms with E. coli.
  • ARHPHPH was proteolyzed from κ-casein in the growth medium by E. faecalis.
  • Thirteen cytosolic and membrane proteins associated with the cell surface were identified in E. faecalis V583 biofilms.
  • Enolase and GAPDH, identified proteins, are glycolytic enzymes with known roles in bacterial virulence.

Conclusions:

  • A powerful MALDI-MS-based approach was developed for discovering and localizing multiple peptides and proteins within intact biofilms.
  • The heptapeptide ARHPHPH is a novel component of E. faecalis biofilms, derived from dietary casein.
  • The study identified key E. faecalis biofilm proteins, including virulence-associated enzymes like enolase and GAPDH.
  • This work provides new insights into the molecular architecture and potential virulence factors of E. faecalis biofilms.

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