(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Bacteria: NE > Proteobacteria: NE > Alphaproteobacteria: NE > Rhizobiales: NE > Brucellaceae: NE > Ochrobactrum: NE > Ochrobactrum sp. T63: NE
Molecular evidence
Database
No mutation 6 structures(e.g. : 4G5X, 4G8B, 4G8C... more)(less) 4G5X: Crystal structure of N-acyl homoserine lactonase AidH from Ochrobactrum, 4G8B: Crystal structure of N-acyl homoserine lactonase AidH from Ochrobactrum S102G mutant complexed with N-hexanoyl homoserine lactone, 4G8C: Crystal structure of N-acyl homoserine lactonase AidH from Ochrobactrum E219G mutant complexed with N-hexanoyl homoserine, 4G8D: Crystal structure of N-acyl homoserine lactonase AidH from Ochrobactrum S102G mutant, 4G9E: Crystal structure of N-acyl homoserine lactonase AidH from Ochrobactrum complexed with N-butanoyl homoserine, 4G9G: Crystal structure of N-acyl homoserine lactonase AidH from Ochrobactrum E219G mutant No kinetic
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MTINYHELETSHGRIAVRESEGEGAPLLMIHGNSSSGAIFAPQLEGEIGK KWRVIAPDLPGHGKSTDAIDPDRSYSMEGYADAMTEVMQQLGIADAVVFG WSLGGHIGIEMIARYPEMRGLMITGTPPVAREEVGQGFKSGPDMALAGQE IFSERDVESYARSTCGEPFEASLLDIVARTDGRARRIMFEKFGSGTGGNQ RDIVAEAQLPIAVVNGRDEPFVELDFVSKVKFGNLWEGKTHVIDNAGHAP FREAPAEFDAYLARFIRDCTQ
Many pathogenic bacteria that infect humans, animals and plants rely on a quorum-sensing (QS) system to produce virulence factors. N-Acyl homoserine lactones (AHLs) are the best-characterized cell-cell communication signals in QS. The concentration of AHL plays a key role in regulating the virulence-gene expression and essential biological functions of pathogenic bacteria. N-Acyl homoserine lactonases (AHL-lactonases) have important functions in decreasing pathogenicity by degrading AHLs. Here, structures of the AHL-lactonase from Ochrobactrum sp. (AidH) in complex with N-hexanoyl homoserine lactone, N-hexanoyl homoserine and N-butanoyl homoserine are reported. The high-resolution structures together with biochemical analyses reveal convincing details of AHL degradation. No metal ion is bound in the active site, which is different from other AHL-lactonases, which have a dual Lewis acid catalysis mechanism. AidH contains a substrate-binding tunnel between the core domain and the cap domain. The conformation of the tunnel entrance varies with the AHL acyl-chain length, which contributes to the binding promiscuity of AHL molecules in the active site. It also supports the biochemical result that AidH is a broad catalytic spectrum AHL-lactonase. Taken together, the present results reveal the catalytic mechanism of the metal-independent AHL-lactonase, which is a typical acid-base covalent catalysis.
Title: AidH, an alpha/beta-hydrolase fold family member from an Ochrobactrum sp. strain, is a novel N-acylhomoserine lactonase Mei GY, Yan XX, Turak A, Luo ZQ, Zhang LQ Ref: Applied Environmental Microbiology, 76:4933, 2010 : PubMed
N-acylhomoserine lactones (AHLs) are signaling molecules in many quorum-sensing (QS) systems that regulate interactions between various pathogenic bacteria and their hosts. Quorum quenching by the enzymatic inactivation of AHLs holds great promise in preventing and treating infections, and several such enzymes have been reported. In this study, we report the characterization of a novel AHL-degrading protein from the soil bacterium Ochrobactrum sp. strain T63. This protein, termed AidH, shares no similarity with any of the known AHL degradases but is highly homologous with a hydrolytic enzyme from Ochrobactrum anthropi ATCC 49188 that contains the alpha/beta-hydrolase fold. By liquid chromatography-mass spectrometry (MS) analysis, we demonstrate that AidH functions as an AHL-lactonase that hydrolyzes the ester bond of the homoserine lactone ring of AHLs. Mutational analyses indicate that the G-X-Nuc-X-G motif or the histidine residue conserved among alpha/beta-hydrolases is critical for the activity of AidH. Furthermore, the AHL-inactivating activity of AidH requires Mn(2+) but not several other tested divalent cations. We also showed that AidH significantly reduces biofilm formation by Pseudomonas fluorescens 2P24 and the pathogenicity of Pectobacterium carotovorum, indicating that this enzyme is able to effectively quench QS-dependent functions in these bacteria by degrading AHLs.
Ochrobactrum sp. T63 AidH acyl homoserine lactonase
