Johan M. Thevelein is a Belgian molecular biologist. He is emeritus professor of molecular cell biology at the Katholieke Universiteit Leuven (KU Leuven), former director of the Department of Molecular Microbiology of the Vlaams Instituut voor Biotechnologie (VIB), and founder and managing director of the yeast biotechnology company NovelYeast bv. His research addresses the molecular genetics and biochemistry of nutrient sensing and signalling as well as stress tolerance in the yeast Saccharomyces cerevisiae, and its applications to industrial fermentation with cell factory yeasts and, more recently, to cancer cell metabolism.
Education and academic career Thevelein completed a master's degree in biology at KU Leuven in 1977 and obtained a PhD there in 1981. He then carried out postdoctoral research in the Department of Molecular Biophysics and Biochemistry at Yale University in New Haven (CT), United States, from 1981 to 1983. He then joined KU Leuven again as senior researcher of the FWO and was appointed assistant professor in 1986, professor in 1992, and served as full professor from 1996 until his retirement in 2020, when he became emeritus professor. He headed the Section of Molecular Microbiology and Biotechnology at KU Leuven from 1994 to 2014 and was vice-chairman of the KU Leuven Department of Biology from 2010 to 2014.
At VIB, Thevelein was director and group leader of the Department of Molecular Microbiology from 2002 to 2016, and subsequently senior group leader at the VIB Center for Microbiology from 2017 until 2020. He also held an appointment as extraordinary professor in microbiology at the University of Stellenbosch, South Africa, from 2002 to 2010, and was a Special Visiting Researcher in Brazil under the Science Without Borders programme from 2012 to 2015. Following his retirement from KU Leuven and VIB in 2020, he has continued to publish as an emeritus professor and to lead his own company.
Former involvement with GlobalYeast In 2015, KU Leuven, VIB and the Brazilian investment company Performa Investimentos established GlobalYeast, a spin-off company built on Thevelein's yeast strain research and intended to develop industrial yeast strains for bioethanol and green chemical production, principally for the Brazilian market. Thevelein was named at the company's launch as its scientific founder and Chief Scientific Officer, responsible for all research and for the continued development of its technology platform. He held the role until 2018. The Belgian GlobalYeast NV was voluntarily liquidated in 2019.
NovelYeast NovelYeast bv was incorporated on 11 August 2019, shortly before Thevelein's retirement from KU Leuven and VIB, and is registered in Oud-Heverlee, Belgium, with laboratory facilities at the Leuven Bio-Incubator in Leuven-Heverlee. Thevelein is its founder, owner and managing director, a position he continues to hold. NovelYeast develops industrial yeast strains and associated fermentation processes for a broad range of target applications that include bioethanol production, isobutanol, lactic acid, 2,3-butanediol and other bio-based chemicals, specialty sugars such as isomaltulose, allulose and xylitol, flavour compounds, alcoholic beverages, plastic recycling, cellulose-fiber degumming and probiotic yeast engineering NovelYeast operates approximately 305 m² of laboratory space and has a team of 14 employees.
Research Thevelein's research has focused on the molecular mechanisms by which yeast cells sense and respond to nutrients, generate stress tolerance and on the application of that basic research to industrial biotechnology and, in his most recent work, to cancer cell metabolism. His KU Leuven research profile lists his principal topics as nutrient sensing and signal transduction in yeast, the cAMP–protein kinase A signalling pathway, trehalose metabolism in yeast and higher plants, determinants of stress resistance, the development of industrial yeast strains with improved stress resistance, polygenic analysis of commercially important traits, and the functional characterisation of mammalian genes of medical importance in yeast.
Nutrient sensing and glucose signalling Since the late 1980s, Thevelein's group has studied how S. cerevisiae senses available nutrients, principally sugars, amino acids, phosphate, sulfate and minerals, and converts that information into signals that adjust metabolism, stress tolerance, fermentation and cell growth, in particular via the camp protein kinase A (PKA) pathway. Work on the TPS1/FDP1 gene and its role in controlling glucose influx into glycolysis was among the earliest research linking trehalose metabolism to glucose sensing and fermentation capacity in yeast.
Discovery of the yeast glucose receptor Gpr1 In 1999, Thevelein's group, with collaborators, identified Gpr1, a yeast G protein-coupled receptor required for glucose activation of the cAMP–PKA pathway. The finding was the first demonstration of a G protein-coupled receptor activated directly by a nutrient rather than by a hormone or other signaling ligand, and has served as the first evidence for a broader class of nutrient-sensing GPCRs.
Transceptors Building on the Gpr1 work, Thevelein's group proposed and provided the first evidence for the concept of the transceptor, a nutrient transporter protein that also functions as a signalling receptor. Thevelein first presented the concept at a scientific meeting in 1999, and his group subsequently published evidence that the general amino acid permease Gap1 acts as an amino-acid sensor independently of its transport function, representing the first characterised nutrient transceptor. The group went on to identify further transceptors among transporters for other nutrients, including phosphate, ammonium, sulfate, zinc and iron, and reviewed the concept and its evolutionary implications in later publications. Since then, many other transceptors have been identified in cells of fungi, plants, animals, as well as humans.
Glycerol metabolism and osmoregulation With Stefan Hohmann and in collaboration with other research groups, Thevelein's group contributed seminal findings to yeast glycerol metabolism and its role in osmoregulation, including the discovery of Fps1, a channel protein of the yeast plasma membrane that facilitates glycerol uptake and efflux and is central to the cell's response to osmotic stress. The group also succeeded in cloning GPD1, encoding glycerol-3-phosphate dehydrogenase, and identifying it as essential for yeast growth under osmotic stress and regulated by the high-osmolarity glycerol (HOG) signalling pathway.
Fructose-1,6-bisphosphate, Ras and the Warburg effect In 2017, Thevelein's group reported that fructose-1,6-bisphosphate, a crucial intermediate of glycolysis, directly activates the Ras signalling protein in yeast, and showed that glucose similarly activates Ras and its downstream targets MEK and ERK in mammalian cells. The finding, which links the fermentative metabolism shared by yeast and many cancer cells, known as the Warburg effect, to a conserved mechanism of Ras activation, was reported extensively in the science press. The study's authors noted that the findings do not yet identify the primary cause of the Warburg effect in cancer, and that further research would be required to establish whether the same underlying primary cause is conserved in yeast.
Extending this line of work, the group later reported a family of compounds named Warbicin®, which inhibit glucose uptake in both yeast and human cells, depending on the presence of active glucose phosphorylation, and restrain the proliferation of cancer cells in laboratory experiments, apparently by targeting a novel mechanism possibly related to transport-associated phosphorylation of glucose. As of 2024 this research remained at a laboratory stage in which the Warbicin® compounds also showed lack of toxicity in mice suggesting promising potential for increasing the sensitivity of cancer cells to anti-cancer treatments by inhibiting the Warburg effect; the compounds are the subject of patent applications but have not been established yet in clinical practice as a cancer treatment.
Human intestinal glucose sensing Thevelein's group has also extended its nutrient-sensing work to mammalian systems. In a study the authors explicitly link to their earlier discovery of the yeast glucose receptor Gpr1, the group reported that the human β2-adrenergic receptor is expressed at the apical membrane of intestinal enterocytes and senses dietary sugars to stimulate glucose uptake from the gut via the sodium/glucose cotransporter SGLT1. The work situates the receptor within the broader evolutionary framework of nutrient transceptors that Thevelein had proposed in earlier publications.
Industrial and applied research In parallel with his basic research, Thevelein's laboratory has developed industrial S. cerevisiae strains for first- and second-generation bioethanol production, including strains engineered to ferment the pentose sugar xylose from inhibitor-rich lignocellulose hydrolysates derived from agricultural residues and other biomass feedstocks. This work has included international collaborations on the industrial application of engineered strains in consolidated bioprocessing, and on fermentation routes to bio-based chemicals such as 2,3-butanediol and isobutanol. This work is now being extended in the company NovelYeast.
Thevelein's laboratory contributed to a multi-institution 2020 study in Science describing an integrated wood biorefinery that converts lignin into commodity chemicals with a lower carbon footprint than fossil-based production; the project was led by the group of chemist Bert Sels at KU Leuven, with Thevelein's laboratory contributing expertise relevant to converting the resulting carbohydrate pulp to bioethanol.Similarly, Thevelein was a contributing co-author on a widely cited 2007 study in Nature, led by Elena Baena-González and Jen Sheen, identifying the plant kinases KIN10 and KIN11 as central integrators of stress and energy signalling in Arabidopsis thaliana.
Scientific output Thevelein has authored more than three hundred peer-reviewed journal articles and book chapters over a research career spanning more than four decades, and is an inventor or co-inventor on about fifty granted patents and patent applications relating to industrial yeast strains and their use in fermentations, as well as glucose-sensing and uptake inhibitors. As of 2026, his publications had received more than 42,800 citations on Google Scholar, and yielded an h-index of 114.
Selected publications
Kraakman L, Lemaire K, Ma P, Teunissen AW, Donaton MC, Van Dijck P, Winderickx J, de Winde JH, Thevelein JM (1999). "A Saccharomyces cerevisiae G-protein coupled receptor, Gpr1, is specifically required for glucose activation of the cAMP pathway during the transition to growth on glucose." Molecular Microbiology 32(5):1002–1012. Donaton MC, Holsbeeks I, Lagatie O, Van Zeebroeck G, Crauwels M, Winderickx J, Thevelein JM (2003). "The Gap1 general amino acid permease acts as an amino acid sensor for activation of protein kinase A targets in the yeast Saccharomyces cerevisiae." Molecular Microbiology 50(3):911–929.
Thevelein JM, Voordeckers K (2009). "Functioning and evolutionary significance of nutrient transceptors." Molecular Biology and Evolution 26(11):2407–2414.
Baena-González E, Rolland F, Thevelein JM, Sheen J (2007). "A central integrator of transcription networks in plant stress and energy signalling." Nature 448(7156):938–942.
Peeters K, Van Leemputte F, Fischer B, et al., Thevelein JM (2017). "Fructose-1,6-bisphosphate couples glycolytic flux to activation of Ras." Nature Communications 8:922.
Liao Y, Koelewijn SF, Van den Bossche G, et al., Sels BF (2020). "A sustainable wood biorefinery for low-carbon footprint chemicals production." Science 367(6484):1385–1390.