Structural determinants driving homoserine lactone ligand selection in the Pseudomonas aeruginosa LasR quorum-sensing receptor

Abstract

Quorum sensing is a cell-cell communication process that bacteria use to orchestrate group behaviors. Quorum sensing is mediated by signal molecules called autoinducers. Autoinducers are often structurally similar, raising questions concerning how bacteria distinguish among them. Here, we use the Pseudomonas aeruginosa LasR quorum-sensing receptor to explore signal discrimination. The cognate autoinducer, 3OC 12 homoserine lactone (3OC 12 HSL), is a more potent activator of LasR than other homoserine lactones. However, other homoserine lactones can elicit LasR-dependent quorum-sensing responses, showing that LasR displays ligand promiscuity. We identify mutants that alter which homoserine lactones LasR detects. Substitution at residue S129 decreases the LasR response to 3OC 12 HSL, while enhancing discrimination against noncognate autoinducers. Conversely, the LasR L130F mutation increases the potency of 3OC 12 HSL and other homoserine lactones. We solve crystal structures of LasR ligand-binding domains complexed with noncognate autoinducers. Comparison with existing structures reveals that ligand selectivity/ sensitivity is mediated by a flexible loop near the ligand-binding site. We show that LasR variants with modified ligand preferences exhibit altered quorum-sensing responses to autoinducers in vivo. We suggest that possessing some ligand promiscuity endows LasR with the ability to optimally regulate quorum-sensing traits.crystal structure | LasR | Pseudomonas aeruginosa | quorum sensing | homoserine lactone

Attenuation of Pseudomonas aeruginosa Quorum Sensing by Natural Products: Virtual Screening, Evaluation and Biomolecular Interactions

“…Here, it is noteworthy to mention that docking results revealed butein was able to form H-bond with carbonyl oxygen of Tyr 47. McCready et al, 2018, reported that Tyr 47 present in loop L3 of LasR is able to adopt multiple conformations and hence it can accommodate the different ligands [23]. When LasR Tyr 47 was mutated with other amino acids such as Ser and Arg, the sensitivity to towards AHLs was found to be decreased.…”

Mechanism underlying autoinducer recognition in theVibrio choleraeDPO-VqmA quorum-sensing pathway

“…Distinct from both of these cases, VqmA binds to either DPO or Ala-AA, but not both, to induce maximal transcriptional activity. This result is curious to us given that QS receptors typically maintain signaling fidelity by distinguishing between different ligands (30)(31)(32)(33). This situation appears analogous to that of the V. cholerae AI called CAI-1 ((S)-3hydroxytridecan-4-one) and its biosynthetic precursor, Ea-CAI-1 (3-aminotridec-2-en-4-one).…”

“…Intra-molecular reclosure was performed as described (10) using Q5 High-Fidelity DNA Polymerase (NEB). QuickChange (Agilent) site directed mutagenesis was performed as described (30) using PfuUltra Polymerase (Agilent). The parent pET15b-vqmA vector (JSS-1057) was constructed by PCR of pET15b-His-vqmA (KPS-0929) with primers JSO-654 x JSO-655, followed by intramolecularreclosure to remove the His-tag.…”

“…Thermal-shift analyses of VqmA were performed as described (30). In brief, VqmA was diluted to 5 μM in reaction buffer (20 mM Tris-HCl pH 8, 150 mM NaCl) containing either 10 μM synthetic DPO, 10 μM synthetic Ala-AA, or an equivalent volume of water in an 18 μL reaction (final vol).…”

Prophage induction mediated by quorum sensing signals alters soil bacterial community structure

“…Quorum sensing for cell-density dependent communication among bacteria enables coordinated gene expression 17,18 . Quorum-sensing bacteria produce signaling molecules, such as different types of N-Acyl homoserine lactones (AHLs), with the concentration of released signaling molecules dependent upon bacterial population density [19][20][21] .…”