Structural Determinants for Activity and Specificity of the Bacterial Toxin LlpA

PLoS Pathogens

Maarten G. K. Ghequire¹  Stijn Spaepen¹  Remy Loris¹  René De Mot²  Abel Garcia-Pino²  Eline K. M. Lebbe³ 

[1] Centre of Microbial and Plant Genetics, University of Leuven, Heverlee-Leuven, Belgium;Molecular Recognition Unit, Department of Structural Biology, Vlaams Instituut voor Biotechnologie, Brussel, Belgium;Structural Biology Brussels, Department of Biotechnology (DBIT), Vrije Universiteit Brussel, Brussel, Belgium

关键词: Lectins;    Pseudomonas syringae;    Mannose;    Sequence motif analysis;    Carbohydrates;    Pseudomonas putida;    Bacteria;    Antibacterials;   

DOI  :  10.1371/journal.ppat.1003199

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Lectin-like bacteriotoxic proteins, identified in several plant-associated bacteria, are able to selectively kill closely related species, including several phytopathogens, such as Pseudomonas syringae and Xanthomonas species, but so far their mode of action remains unrevealed. The crystal structure of LlpABW, the prototype lectin-like bacteriocin from Pseudomonas putida, reveals an architecture of two monocot mannose-binding lectin (MMBL) domains and a C-terminal β-hairpin extension. The C-terminal MMBL domain (C-domain) adopts a fold very similar to MMBL domains from plant lectins and contains a binding site for mannose and oligomannosides. Mutational analysis indicates that an intact sugar-binding pocket in this domain is crucial for bactericidal activity. The N-terminal MMBL domain (N-domain) adopts the same fold but is structurally more divergent and lacks a functional mannose-binding site. Differential activity of engineered N/C-domain chimers derived from two LlpA homologues with different killing spectra, disclosed that the N-domain determines target specificity. Apparently this bacteriocin is assembled from two structurally similar domains that evolved separately towards dedicated functions in target recognition and bacteriotoxicity.

【 授权许可】

CC BY