ChemBioChem [CBAT/Biogéochimie moléculaire]

Abstract:

The lipid cis-trans isomerase (Cti) is a periplasmic heme-c enzyme found in several bacteria including Pseudomonas aeruginosa, a pathogen known for causing nosocomial infections. This metalloenzyme catalyzes the cis-trans isomerization of unsaturated fatty acids in order to rapidly modulate membrane fluidity in response to stresses that impede bacterial growth. As a consequence, breakthrough in the elucidation of the mechanism of this metalloenzyme might lead to new strategies to combat bacterial antibiotic resistance. We report the first comprehensive biochemical, electrochemical and spectroscopic characterization of a Cti enzyme. This has been possible by the successful purification of Cti from P. aeruginosa (Pa-Cti) in favorable yields with enzyme activity of 0.41 μmol/min/mg when tested with palmitoleic acid. Through a synergistic approach involving enzymology, site-directed mutagenesis, Raman spectroscopy, Mössbauer spectroscopy and electrochemistry, we identified the heme coordination and redox state, pinpointing Met163 as the sixth ligand of the Fe^II of heme-c in Pa-Cti. Significantly, the development of an innovative assay based on liposomes demonstrated for the first time that Cti catalyzes cis-trans isomerization directly using phospholipids as substrates without the need of protein partners, answering the important question about the substrate of Cti within the bacterial membrane.

 

Reference :

Towards Bacterial Resistance via the Membrane Strategy: Enzymatic, Biophysical and Biomimetic Studies of the Lipid cis-trans Isomerase of Pseudomonas aeruginosa

Dr. Mickaël Mauger, Dr. Iryna Makarchuk, Yasmin Molter, Dr. Anna Sansone, Dr. Frédéric Melin, Dr. Philippe Chaignon, Dr. Philippe Schaeffer, Dr. Pierre Adam, Prof. Volker Schünemann, Prof. Petra Hellwig, Dr. Carla Ferreri, Dr. Chryssostomos Chatgilialoglu, and Dr. Myriam Seemann.

ChemBioChem, First published: 14 November 2024 – DOI: https://doi.org/10.1002/cbic.202400844

Contacts:

Myriam Seemann (team CBAT) and Pierre Adam (team Biogéochimie moléculaire), Institut de Chimie de Strasbourg (UMR 7177).