One point mutation can overturn sugar-binding specificity of lectin RS-IIL from plant pathogen Ralstonia solanacearum
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| Year of publication | 2015 |
| Type | Conference abstract |
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| Description | A soil bacterium Ralstonia solanacearum is an aggressive phytopathogen which causes severe wilts of many economically important crops in tropical and subtropical regions. This pathogen produces two lectins: RSL and RS-IIL. Lectins are sugar-binding proteins different from sugar-specific antibodies or enzymes. They often play an important role in host-pathogen recognition and interactions. Lectin RS-IIL belongs to a so-called “PA-IIL family”, which includes also lectins PA-IIL (from P. aeruginosa), CV-IIL (from C. violaceum), BC2L-A and BC2L-C (from B. cenocepacia). These lectins are orthologs with significant sequential and structural similarities. Although they bind saccharides with similar stereochemistry, they differ in preferences towards these saccharides. This fact is caused by differences in three amino acids which are arranged in the so-called “specificity binding loop”. Adam et al. prepared three point mutants of the PA-IIL lectin to investigate the fine specificity. They replaced each of the amino acid of the “specificity loop” for those present in RS-IIL. Subsequent structural and thermodynamic studies confirmed that amino acid in the position 22 is mainly responsible for sugar binding specificity. Mutation in this position led to overturn of sugar preference of PA-IIL to the RS-IIL one. In our work we prepared a mutant of the RS-IIL lectin with substitution of amino acid in position 22 to the one present in PA-IIL “specificity loop” to test possibility of overturn of sugar preference of RS-IIL to the PA-IIL one. We used surface plasmon resonance and isothermal titration microcalorimetry to investigate interactions of this mutant with saccharides. During this work we also improved fast and cheap method for fast determination of lectin specificity by agglutination using microscopy. |
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