| Aspect | Key details | Key references | URL/DOI |
|---|---|---|---|
| Reaction | **UniProt Q88IU8 / pvdQ / PP_2901** is annotated as **acyl-homoserine lactone acylase PvdQ (EC 3.5.1.97)**. The catalyzed reaction is **amide-bond hydrolysis** of N-acyl-L-homoserine lactones to release **homoserine lactone + the corresponding fatty acid**; this is the established chemistry for PvdQ-family AHL acylases, but **not directly biochemically demonstrated for the P. putida KT2440 protein in the retrieved literature**. Direct enzymology is from homologous **P. aeruginosa** PvdQ and engineered PvdQ studies (pqac-00000007, pqac-00000011). | Bokhove 2010, *PNAS*; Sompiyachoke & Elias 2024, *Protein Science* | https://doi.org/10.1073/pnas.0911839107; https://doi.org/10.1002/pro.4954 |
| Substrates | PvdQ shows preference for **long-chain AHLs**. Structural and biochemical work on homologous **P. aeruginosa** PvdQ supports activity toward **C12-HSL and 3-oxo-C12-HSL**; review/engineering sources summarize preference for **acyl chains >8 carbons** and earlier reports of activity on **C8-HSL, C12-HSL, 3-oxo-C12-HSL** but not **C4-HSL** in that species. For **Q88IU8 in P. putida**, substrate range is **inferred by homology**, not directly shown in the retrieved primary literature (pqac-00000001, pqac-00000006, pqac-00000007, pqac-00000011, pqac-00000012). | Bokhove 2010, *PNAS*; Utari et al. 2017, *Front. Microbiol.*; Sompiyachoke & Elias 2024, *Protein Science* | https://doi.org/10.1073/pnas.0911839107; https://doi.org/10.3389/fmicb.2017.01123; https://doi.org/10.1002/pro.4954 |
| Mechanism | PvdQ is an **N-terminal nucleophile (Ntn) hydrolase**. The mature catalytic nucleophile is **Serβ1**; the **oxyanion hole** includes **Valβ70** and **Asnβ269/278** (numbering differs slightly by source). A **covalent acyl-enzyme intermediate** and induced-fit opening of the acyl pocket gated by **Pheβ24** were observed in structural studies. A high-resolution homolog structure was solved at **1.8 Å**. These mechanistic data are from **P. aeruginosa PvdQ / engineered PvdQ**, and are **inferred for P. putida Q88IU8** because UniProt/domain architecture matches the same S45/Ntn-hydrolase family (pqac-00000000, pqac-00000007, pqac-00000009, pqac-00000015). | Bokhove 2010, *PNAS*; Sompiyachoke & Elias 2024, *Protein Science* | https://doi.org/10.1073/pnas.0911839107; https://doi.org/10.1002/pro.4954 |
| Processing | PvdQ is synthesized as a **single precursor** that undergoes **autoproteolytic maturation** to an **α/β heterodimer**. Reported sizes for the homologous mature enzyme are approximately **α-chain 171 aa / ~18 kDa** and **β-chain 546 aa / ~60 kDa**, generated after excision of a short linker/prosegment (including a reported **23-residue prosegment** in structural work). This processing is experimentally demonstrated for **P. aeruginosa** PvdQ and strongly supported for **P. putida Q88IU8** by the UniProt precursor annotation and conserved family assignment, but direct maturation data for KT2440 were not retrieved (pqac-00000000, pqac-00000002, pqac-00000006, pqac-00000007). | Bokhove 2010, *PNAS*; Rice 2010 thesis; Utari et al. 2017, *Front. Microbiol.* | https://doi.org/10.1073/pnas.0911839107; https://doi.org/10.3389/fmicb.2017.01123 |
| Localization | Multiple lines of homolog evidence indicate **periplasmic localization**: presence of an **N-terminal signal peptide / Sec-type export motif**, disulfide-bond-rich mature structure, and explicit reports that PvdQ acts as a **periplasmic hydrolase**. For **P. putida Q88IU8**, localization is therefore **best interpreted as periplasmic, inferred from strong homology and precursor/signal-peptide annotation**, but no direct KT2440 localization experiment was retrieved (pqac-00000000, pqac-00000002, pqac-00000004, pqac-00000005, pqac-00000006). | Rice 2010 thesis; Drake & Gulick 2011, *ACS Chem. Biol.*; Bokhove 2010, *PNAS* | https://doi.org/10.1021/cb2002973; https://doi.org/10.1073/pnas.0911839107 |
| Pathway role | **Important disambiguation:** the symbol **pvdQ** is associated with pyoverdine gene clusters in fluorescent pseudomonads, but the **best direct pathway evidence is from P. aeruginosa**, where PvdQ removes a **myristoyl/fatty-acyl group** from an acylated pyoverdine precursor (**PVDIq**) in the **periplasm**, linking the enzyme to **pyoverdine maturation** as well as quorum-quenching. For **P. putida KT2440 Q88IU8**, a pyoverdine-related role is **plausible by orthology/name**, but the retrieved literature did **not** provide direct biochemical demonstration in KT2440 (pqac-00000001, pqac-00000004). | Drake & Gulick 2011, *ACS Chem. Biol.*; Clevenger 2015 thesis | https://doi.org/10.1021/cb2002973; https://doi.org/10.15781/t2j35z |
| Evidence in *P. putida* | **Direct species-specific evidence for KT2440 is limited in the retrieved set.** A 2024 study experimentally **deleted pvdQ in P. putida KT2440** and found that loss/downregulation caused **increased outer-membrane-vesicle-associated protein and lipid signal** (hypervesiculation phenotype) in a vesiculation screen. This supports that **PP_2901 is an active cellular determinant in envelope/vesicle physiology**, but it does **not directly establish its biochemical substrate or reaction** in KT2440 (pqac-00000008). | Bitzenhofer et al. 2024, *Microbial Biotechnology* | https://doi.org/10.1111/1751-7915.14312 |
| Evidence in *P. aeruginosa* / other | The homologous **P. aeruginosa** enzyme is extensively characterized: **1.8 Å** structure; long-chain AHL-binding pocket; **α/β maturation**; **Serβ1** catalytic nucleophile; role in **pyoverdine precursor deacylation**; quorum-quenching activity against **long-chain AHLs**. Engineering work further quantified performance: WT-PvdQ **kcat/KM ~2.22×10^4 s^-1 M^-1 for 3-oxo-C12-HSL** and **~1.75×10^3 s^-1 M^-1 for C8-HSL** in one 2024 assay format; designed variants increased **Tm by 9.2, 11.7, and 13.2 °C** and improved solvent/coating robustness. These data are the main basis for **functional inference to Q88IU8** (pqac-00000000, pqac-00000004, pqac-00000007, pqac-00000010, pqac-00000012). | Bokhove 2010, *PNAS*; Drake & Gulick 2011, *ACS Chem. Biol.*; Sompiyachoke & Elias 2024, *Protein Science* | https://doi.org/10.1073/pnas.0911839107; https://doi.org/10.1021/cb2002973; https://doi.org/10.1002/pro.4954 |


*Table: This table summarizes the most relevant functional annotation points for UniProt Q88IU8 (Pseudomonas putida KT2440 pvdQ/PP_2901), separating direct evidence in P. putida from stronger mechanistic and biochemical evidence available for homologous PvdQ proteins, especially from P. aeruginosa.*