Abstrakt

In the previous study we found that the expression of the metagenomic - derived methylthioadenosine phosphorylase gene (rsfp) in E. coli cells and the presence of rhodamine B in the growth medium were crucial for the pink fluorescence of one E. coli colony from Antarctic soil metagenomic library (Cieśliński et al., 2009). In this study, rsfp gene expression was induced by an arabinose promoter in an LMG194 E. coli strain and the RSFP protein was then purified with using fast protein liquid chromatography. Purified, recombinant RSFP enabled us to examine the hypothesis that it is the binding of RB molecules to RSFP proteins that was responsible for the observed fluorescence phenomena. Indeed, it was with this in mind that absorbance and fluorescence measurements were employed, as they have already been successfully used in studies of RB molecule interaction with carrier surfaces such as clay particles, quartz, gold nanoparticles, hydrophilic glass slides and bovine serum albumin. The results of this study revealed that the rhodamine B molecules binding to RSFP protein caused remarkable changes in UV-VIS absorption and fluorescence spectra of rhodamine B and induces conformational changes in the protein structure. What was important to note is that the analysis of the presented results in the light of the literature study reveal: (i) the lack of literature data on rhodamine B interaction with any proteins belonging to the class of methylthioadenosine phosphorylase enzymes and/or influence on their enzymatic activities, (ii) that the interaction between rhodamine B molecules and proteins are crucial for observed carcinogenic properties of RB, however the knowledge of the interaction mechanism of RB with proteins is very limited, and (iii) that the methylthioadenosine phosphorylase enzymes are studied in details due to their roles in biological processes such as methionine salvage methylation reactions, purine salvage, and polyamine biosynthesis.

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