PHD Defense of Nina Marietta NIMBONA - June 5th, 2026

Title of the PHD défense : Biochemical and Structural Characterization of Arylsulfate Sulfotransferases (ASST)

The defense will take place in the Conference Room of the Station Biologique de Roscoff on Friday, June 5th, 2026, at 2:00 PM.

This doctoral work was carried out under the supervision of Mirjam Czjzek and Lionel Cladière.

The defense will be held in front of the following jury:

• Stéphane Egée, Professor, Sorbonne Université (Roscoff) – Examiner
• Coralie Bompard, CNRS Research Scientist (Lille) – Examiner
• Tristan Wagner, CEA Research Scientist (Grenoble) – Examiner
• Isabelle Broutin, CNRS Research Director (Paris) – Reviewer
• Pascal Arnoux, CEA Research Director (Cadarache) – Reviewer
• Lionel Cladière, Associate Professor, Sorbonne Université (Roscoff) – Co-supervisor
• Mirjam Czjzek, CNRS Research Director (Roscoff) – PhD Supervisor

Abstract 

Sulfotransferases are enzymes that catalyze the transfer of sulfate groups to specific metabolites. They are divided into two major families: PAPS-dependent sulfotransferases, predominantly found in eukaryotes, and PAPS-independent sulfotransferases, also known as arylsulfate sulfotransferases (ASSTs), mainly found in prokaryotes and still poorly characterized.

This thesis work led to the purification of 15 enzymes and the determination of three new ASST structures by X-ray crystallography. These findings provided new insights into the catalytic mechanisms of these enzymes and highlighted key residues involved in catalysis and substrate recruitment. This work opens promising perspectives for a deeper understanding of ASSTs and their potential applications in enzyme-assisted chemistry.