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Molecular and functional characterisation of the Serratia marcescens outer membrane protein Omp1

Neus Ruiz1, Elke Maier, Christian Andersen

  • 1Laboratory of Microbiology. Biomedical Research Centre of Bellvitge, University of Barcelona, E-08907 L'Hospitalet, Barcelona, Spain.

Biophysical Chemistry
|April 28, 2004
PubMed

Insights

Serratia marcescens outer membrane porin 1 (Omp1) was expressed in E. coli, increasing antibiotic susceptibility. Purified Omp1 functions as a channel, aiding in topology modeling of enteric bacterial porins.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Serratia marcescens outer membrane possesses three general diffusion porins: Omp1, Omp2, and Omp3.
  • Outer membrane porins facilitate nutrient transport and influence antibiotic resistance in bacteria.

Purpose of the Study:

  • To clone, express, and characterize the Omp1 porin from Serratia marcescens.
  • To investigate the functional and structural properties of Omp1 and its role in antibiotic susceptibility.

Main Methods:

  • Gene cloning and expression in a porin-deficient E. coli strain.
  • Purification of Omp1 from bacterial outer membranes.
  • Reconstitution of purified Omp1 into black lipid bilayers for electrophysiological analysis.

Main Results:

  • Omp1 expression in E. coli enhanced susceptibility to various antibiotics.
  • Purified Omp1 formed channels with a single-channel conductance of ~2 nS in 1 M KCl.
  • Omp1 demonstrated slight cation selectivity and structural homology to enteric porins, enabling topology model design.

Conclusions:

  • Omp1 functions as a general diffusion porin in Serratia marcescens.
  • The structural and functional characteristics of Omp1 are conserved among enteric bacteria.
  • Omp1's pore structure, including charge distribution, influences its channel properties and potential role in antibiotic permeability.

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