A new Ralstonia solanacearum high affinity mannose-binding lectin
| Authors | |
|---|---|
| Year of publication | 2004 |
| Type | Article in Periodical |
| Magazine / Source | Molecular Microbiology |
| MU Faculty or unit | |
| Citation | |
| Field | Biochemistry |
| Keywords | ralstonia solanacearum; lectin; crystal structure; plant pathogen |
| Description | The plant pathogen Ralstonia solanacearum produces two lectins, each with different affinity for fucose. We described previously the properties and sequence of the first lectin, RSL (subunit Mr 9.9 kDa), that is related to fungal lectins (Sudakevitz, D., Imberty, A., and Gilboa-Garber, N. (2002) J. Biochem. 132: 353-358). The present communication reports the discovery of the second one, RS-IIL (subunit Mr 11.6 kDa), a tetrameric lectin, with high sequence similarity to the fucose-binding lectin PA-IIL of Pseudomanas aeruginosa. RS-IIL recognizes fucose but displays much higher affinity to mannose and fructose, which is opposite to the preference spectrum of PA-IIL. Determination of the crystal structure of RS-IIL complexed with a mannose derivative demonstrates a tetrameric structure very similar to the recently solved PA-IIL structure (Mitchell et al. (2002) Nature Struct. Biol. 9: 918-921). Each monomer contains two close calcium cations which mediate the binding of the monosaccharide and explain the outstandingly high affinity to the monosaccharide ligand. The binding loop of the cations is fully conserved in RS-IIL and PA-IIL while the preference for mannose versus fucose can be attributed to the change of a three amino acids sequence in the "specificity loop". |
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