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| {{STRUCTURE_2op4| PDB=2op4 | SCENE= }} | | {{STRUCTURE_2op4| PDB=2op4 | SCENE= }} |
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| '''Crystal Structure of Quorum-Quenching Antibody 1G9'''
| | ===Crystal Structure of Quorum-Quenching Antibody 1G9=== |
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| ==Overview==
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| A large number of Gram-negative bacteria employ N-acyl homoserine lactones (AHLs) as signaling molecules in quorum sensing, which is a population density-dependent mechanism to coordinate gene expression. Antibody RS2-1G9 was elicited against a lactam mimetic of the N-acyl homoserine lactone and represents the only reported monoclonal antibody that recognizes the naturally-occuring N-acyl homoserine lactone with high affinity. Due to its high cross-reactivity, RS2-1G9 showed remarkable inhibition of quorum sensing signaling in Pseudomonas aeruginosa, a common opportunistic pathogen in humans. The crystal structure of Fab RS2-1G9 in complex with a lactam analog revealed complete encapsulation of the polar lactam moiety in the antibody-combining site. This mode of recognition provides an elegant immunological solution for tight binding to an aliphatic, lipid-like ligand with a small head group lacking typical haptenic features, such as aromaticity or charge, which are often incorporated into hapten design to generate high-affinity antibodies. The ability of RS2-1G9 to discriminate between closely related AHLs is conferred by six hydrogen bonds to the ligand. Conversely, cross-reactivity of RS2-1G9 towards the lactone is likely to originate from conservation of these hydrogen bonds as well as an additional hydrogen bond to the oxygen of the lactone ring. A short, narrow tunnel exiting at the protein surface harbors a portion of the acyl chain and would not allow entry of the head group. The crystal structure of the antibody without its cognate lactam or lactone ligands revealed a considerably altered antibody-combining site with a closed binding pocket. Curiously, a completely buried ethylene glycol molecule mimics the lactam ring and, thus, serves as a surrogate ligand. The detailed structural delineation of this quorum-quenching antibody will aid further development of an antibody-based therapy against bacterial pathogens by interference with quorum sensing.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17400249}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17400249 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17400249}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Induced fit]] | | [[Category: Induced fit]] |
| [[Category: Quorum sensing]] | | [[Category: Quorum sensing]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 11:21:55 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 16:16:16 2008'' |
