Team:Bielefeld-Germany/Project/Porins

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Porins - Overview

By heterologous expression of the pore-forming transmembrane-protein (or porine) OprF from Pseudomona fluorescens a further optimization of the E. coli membrane will be achieved. E. coli possesses several own porines, for example OmpF and OmpC. But these naturally occurring porines are only permeable for molecules smaller than 600 Da, which decreases the range of usable mediators significantly. Opposed to that, porine OprF from P. fluorescence forms one of the biggest known pores in the outer bacterial membrane with a permeability of up to 3000 Da, thus improving the electron shuttle mediated extracellular electron transfer (ETT) and enabling the usage of alternative mediators such as riboflavin (vitamine B2).

Theory

Genetic Approach

Results


Figure 1: Schematic of the enhancement mechanism of electron shuttle-mediated electron transfer between bacteria and the anode of MFCs by the synthetic porin OprF.

Results

Overview

  • The OprF gene from Pseudomonas fluorescens was cloned and heterologously expressed in Escherichia coli KRX under the control of different promoters (Table 1).

Table 1: Overview of OprF devices. Combination of OprF coding BioBrick (<bbpart>BBa_K1172502</bbpart>) with different promotors and RBS.

  • Upon the expression of the outer membrane porin protein OprF, the morphology and physicochemical characteristics of the E. coli surface were measured. SDS-PAGE combined with MALDI-TOF MS/MS, different membrane permeability assays (NPN and ONPG), a hydrophobicity assay and Atomic Force Microscopy (AFM) characterize OprF BioBrick <bbpart>BBa_K1172501</bbpart>.
  • <bbpart>BBa_K1172501</bbpart> – OprF Outer membrane porin from Pseudomonas fluorescens

Figure 1: pSB1C3 – <bbpart>BBa_K1172501</bbpart> OprF BioBrick (1298 bp) was examined by restriction analysis and sequencing.

SDS-PAGE and MALDI-TOF