Régis Hallez

Bacterial cell cycle and development

Understanding how bacterial cell cycle and development are controlled and coordinated, with a special emphasis on the modulation of these processes in response to fluctuations in nutrient availability

Prof. Régis Hallez PhD

UNamur, Department of biology, Research Unit in Biology of Microorganisms (URBM)

Member of the Namur Research Pole in Infectiology (NaRePI)

Research portal UNamur  |  ORCID  |  ResearchGate  |  LinkedIn  |  www.urbm.be/research-groups/regis-hallez

Expertise and research interests

Prof. Régis Hallez, Research Associate at the FNRS since 2015, is leading a research group focusing on bacterial cell cycle control and stress response. The bacterial models used by his team are the Gram-negative alpha-proteobacteria Caulobacter crescentus, Sinorhizobium meliloti and Agrobacterium tumefaciens, and the gamma-proteobacteria Escherichia coli, Salmonella spp. and Acinetobacter baumannii.

End 2018, Régis Hallez received an Incentive Grant for Scientific Research (Mandat d'impulsion scientifique - MIS) from the F.R.S.-FNRS. In 2019, he was awarded a prestigious “Welbio starting grant” to further develop his research on the regulation of bacterial stress by the guanosine penta- or tetra-phosphate (p)ppGpp. This “alarmone”, which is produced by virtually all bacteria in response to fluctuations in nutrient availability, profoundly reshapes the bacterial physiology. His work aims to identify and characterize the cellular machineries targeted by the (p)ppGpp in bacteria. The (p)ppGpp targets involved in the survival of bacteria upon starvation or in reaction to antibiotics will be identified. This project will open avenues towards the development of new therapeutic approaches against multiple drug-resistant (MDR) bacteria. In 2022, Régis Hallez joined a consortium supported by a EOS (Excellence of Science) grant called CRITICAL (deCiphering bacterial peRsIsTence of Individual Cells down to Atomic Level), which aims at identifying and characterising the molecular processes that lead to antibiotics persistence in uropathogenic E. coli. This phenomenon, which allows bacteria to tolerate antibiotics and to regrow after exposure, is responsible for resurgence of chronic urinary infections.

Group members

Postdoc researchers: Dr. Magdalena Chrabaszczewska Poland, Dr. Paul Guiraud France, Dr. Loïc Léger France, Dr. Antony Perrier France and Mari Tagel Estonia

PhD students: Violette Buffet, José Pedro Maio Portugal, Petra Manja, Elie Marchand and Aishwarya Saxena India

Research projects

  • ONGOING Rôle de la modification ARN dihydrouridine chez la bactérie modèle Caulobacter crescentus. Ongoing PhD thesis by Violette Buffet.
  • ONGOING (p)ppGpp-dependent control of bacterial persistence in the uropathogen E. coli (UPEC) UTI89. Ongoing PhD thesis by Petra Manja. Postdoctoral research by Dr. Mari Tagel.
  • ONGOING Dynamic spatio-temporal regulation of peptidoglycan synthesis by the actin-like protein MreB in Caulobacter crescentus. Postdoctoral research by Dr. Paul Guiraud (C2W fellowship).
  • ONGOING Biophysical and structural characterisation of alpha-proteobacterial (p)ppGpp synthetase/hydrolase Rel in complex with regulators. Postdoctoral research by Dr. Magdalena Chrabaszczewska.
  • ONGOING Characterisation of a new RNA-associated protein family highly conserved in alpha-proteobacteria. Postdoctoral research by Dr. Loïc Léger.
  • ONGOING tRNA-dependent regulation of (p)ppGpp synthesis in alpha-proteobacteria. Ongoing PhD thesis by José Pedro Maio.
  • ONGOING Characterization of the functional interplay between the (p)ppGpp alarmone and alternative sigma factors in Caulobacter crescentus. Ongoing PhD thesis by Aishwarya Saxena.
  • ONGOING Study of the stringent response in the context of the multi-drug resistant opportunistic nosocomial pathogen Acinetobacter baumannii. Postdoctoral research by Dr. Antony Perrier.
  • ONGOING Characterization of mechanisms activating (p)ppGpp production upon carbon starvation in alpha-proteobacteria. Ongoing PhD thesis by Elie Marchand.
  • Characterization of the (p)ppGpp-dependent control of virulence in the plant-associated pathogen Agrobacterium tumefaciens. Postdoctoral research by Dr. Tania Gaviria (Jan 2020 - Jul 2024).
  • SpoT regulation during Salmonella infection. Postdoctoral research by Dr. Séverin Ronneau. C2W fellowship (Oct 2022 - June 2024).
  • Impact of the (p)ppGpp-dependent regulation of purine synthesis on cell cycle progression in Caulobacter crescentus. Postdoctoral research by Dr. Alex Quintero Yanes (May 2019 - May 2023).
  • Impact of the transcriptional regulation by (p)ppGpp on bacterial cell cycle progression. Postdoctoral research by Dr. Jérôme Coppine (Oct 2018 - Sep 2021).
  • Phosphotransferase-dependent regulation of cell cycle progression and development in Caulobacter crescentus. Research by Aravind Gopi.

Selected publications

ALL PUBLICATIONS IN PUBMED

Quintero-Yanes A, Léger L, Collignon M, Mignon J, Mayard A, Michaux C, Hallez R. Regulation of potassium uptake in Caulobacter crescentus. J Bacteriol. 2024 Sep 19;206(9):e0010724.

Quintero-Yanes A, Mayard A, Hallez R. The two-component system ChvGI maintains cell envelope homeostasis in Caulobacter crescentus. PLoS Genet. 2022 Dec 8;18(12):e1010465.

Beaufay F, Coppine J, Hallez R. When the metabolism meets the cell cycle in bacteria. Curr Opin Microbiol. 2021 Mar 4;60:104-113.

Coppine J, Kaczmarczyk A, Petit K, Brochier T, Jenal U, Hallez R. Regulation of bacterial cell cycle progression by redundant phosphatases. J Bacteriol. 2020 Aug 10;202(17):e00345-20.

Ronneau S, Hallez R. Make and break the alarmone: regulation of (p)ppGpp synthetase/hydrolase enzymes in bacteria. FEMS Microbiol Rev. 2019 Jul 1;43(4):389-400.

Ronneau S, Caballero-Montes J, Coppine J, Mayard A, Garcia-Pino A, Hallez R. Regulation of (p)ppGpp hydrolysis by a conserved archetypal regulatory domain. Nucleic Acids Res. 2019 Jan 25;47(2):843-854.

Hallez R, Delaby M, Sanselicio S, Viollier PH. Hit the right spots: cell cycle control by phosphorylated guanosines in alphaproteobacteria. Nat Rev Microbiol. 2017 Mar;15(3):137-148.

Ronneau S, Petit K, De Bolle X, Hallez R. Phosphotransferase-dependent accumulation of (p)ppGpp in response to glutamine deprivation in Caulobacter crescentus. Nat Commun. 2016 Apr 25;7:11423.

Beaufay F, De Bolle X, Hallez R. Metabolic control of cell division in α-proteobacteria by a NAD-dependent glutamate dehydrogenase. Commun Integr Biol. 2016 Jan 5;9(1):e1125052.

Contact

regis.hallez@unamur.be