Structural highlights
Publication Abstract from PubMedYersinia pestis produces and secretes a toxin named pesticin that kills related bacteria of the same niche. Uptake of the bacteriocin is required for activity in the periplasm leading to hydrolysis of peptidoglycan. To understand the uptake mechanism and to investigate the function of pesticin we combined crystal structures of the wildtype enzyme, active site mutants and chimera proteins with in vivo and in vitro activity assays. Wildtype pesticin comprises an elongated N-terminal translocation domain, the intermediate receptor binding domain and a C-terminal activity domain with structural analogy to lysozyme homologs. The full length protein is toxic to bacteria when taken up to the target site via the outer or the inner membrane. Uptake studies of deletion mutants in the translocation domain demonstrate their critical size for import. To further test the plasticity of pesticin during uptake into bacterial cells the activity domain was replaced by T4 lysozyme. Surprisingly, this replacement resulted in an active chimera protein which is not inhibited by the immunity protein Pim. Activity of pesticin and the chimera protein was blocked through introduction of disulfide bonds which suggests unfolding as the prerequisite to gain access to the periplasm. Pesticin, a muramidase was characterized by active site mutations demonstrating a similar but not identical residue pattern in comparison to T4 lysozyme. Structure and mechanistic studies of pesticin, a bacterial homolog of phage lysozymes.,Patzer SI, Albrecht R, Braun V, Zeth K J Biol Chem. 2012 May 16. PMID:22593569[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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