4J5F

Crystal Structure of B. thuringiensis AiiA mutant F107W

Summary for 4J5F

• Entry DOI: 10.2210/pdb4j5f/pdb
• Related: 4J5H
• Descriptor: N-acyl homoserine lactonase, ZINC ION, GLYCEROL, ... (4 entities in total)
• Functional Keywords: aiia, lactonase, dizinc hydrolase, substrate specificity, quorum quenching, beta-hairpin loops, n-acyl homoserine lactone, hydrolase
• Biological source: Bacillus thuringiensis
• Total number of polymer chains: 1
• Total formula weight: 29294.97

Authors

Liu, C.F.,Liu, D.,Momb, J.,Thomas, P.W.,Lajoie, A.,Petsko, G.A.,Fast, W.,Ringe, D. (deposition date: 2013-02-08, release date: 2013-06-26, Last modification date: 2024-02-28)

Primary citation

Liu, C.F.,Liu, D.,Momb, J.,Thomas, P.W.,Lajoie, A.,Petsko, G.A.,Fast, W.,Ringe, D.
A phenylalanine clamp controls substrate specificity in the quorum-quenching metallo-gamma-lactonase from Bacillus thuringiensis.
Biochemistry, 52:1603-1610, 2013

PubMed Abstract: Autoinducer inactivator A (AiiA) is a metal-dependent N-acyl homoserine lactone hydrolase that displays broad substrate specificity but shows a preference for substrates with long N-acyl substitutions. Previously, crystal structures of AiiA in complex with the ring-opened product N-hexanoyl-l-homoserine revealed binding interactions near the metal center but did not identify a binding pocket for the N-acyl chains of longer substrates. Here we report the crystal structure of an AiiA mutant, F107W, determined in the presence and absence of N-decanoyl-l-homoserine. F107 is located in a hydrophobic cavity adjacent to the previously identified ligand binding pocket, and the F107W mutation results in the formation of an unexpected interaction with the ring-opened product. Notably, the structure reveals a previously unidentified hydrophobic binding pocket for the substrate's N-acyl chain. Two aromatic residues, F64 and F68, form a hydrophobic clamp, centered around the seventh carbon in the product-bound structure's decanoyl chain, making an interaction that would also be available for longer substrates, but not for shorter substrates. Steady-state kinetics using substrates of various lengths with AiiA bearing mutations at the hydrophobic clamp, including insertion of a redox-sensitive cysteine pair, confirms the importance of this hydrophobic feature for substrate preference. Identifying the specificity determinants of AiiA will aid the development of more selective quorum-quenching enzymes as tools and as potential therapeutics.

PubMed: 23387521
DOI: 10.1021/bi400050j

Experimental method

X-RAY DIFFRACTION (1.72 Å)