Associate Professor Norbert Lehming

Research Interest

The regulation of transcription and the repair of damaged DNA are the topics of interest. Transcription is the basis for the realisation of genetic information, and its regulation is of vital interest for all organisms. All organisms have to be able to repair their DNA when it gets damaged and the inability to repair damaged DNA is a hallmark of cancer. Transcriptional regulation DNA repair are achieved by protein interactions between DNA-bound transcription factors and DNA repair enzymes. Split-Ub, an alternative two-hybrid system, is used to analyse these protein interactions inside living cells. Split-Ub is based upon conditional protein degradation: A protein of interest is fused to the C-terminal half of ubiquitin, which is C-terminally extended by a reporter protein like RUra3p, RGpt2p, or RGFP. In the reporter protein, the first amino acid has been replaced by arginine, an instable residue in the N-end rule pathway of protein degradation.

A second protein of interest can be tested for interaction with the first protein by fusing it to the N-terminal half of ubiquitin. The local concentrations of the two halves of ubiquitin will only be high enough to allow the formation of a native-like ubiquitin if the two proteins interact inside the cell. The native-like ubiquitin is cleaved by the ubiquitin-specific proteases, and the free reporter is degraded by the enzymes of the N-end rule. Therefore, yeast cells become resistant to 5-fluoro orotic acid, a drug counterselecting Ura3p, and human tissue culture cells become resistant to 6-thioguanine, a drug counterselecting Gpt2p, upon interaction of the two proteins inside these cells. The GFP reporter can be used in any organism. The system has been used to screen libraries in order to identify new interaction partners for transcription factors and DNA repair enzymes.

Recent Publications

1. Yip JMX, Chiang GSH, Lee ICJ, Lehming-Teo R, Dai K, Dongol L, Wang LY, Teo D, Seah GT, Lehming N (2025) Mitochondria and the Repurposing of Diabetes Drugs for Off-Label Health Benefits. Int J Mol Sci 26:364. doi: 10.3390/ijms26010364. PMID: 39796218 [5-Year Impact Factor (5YIF) = 5.7; Citations = 17]
2. Mark M, Klein O, Zhang Y, Das K, Elbaz A, Hazan RN, Lichtenstein M, Lehming N, Schuldiner M, Pines O (2023) Systematic Approaches to Study Eclipsed Targeting of Proteins Uncover a New Family of Mitochondrial Proteins. Cells 12:1550. doi: 10.3390/cells12111550. PMID: 37296670 [5YIF = 6.1; Citations = 8]
3. Zhang Y, Karmon O, Das K, Wiener R, Lehming N, Pines O (2022) Ubiquitination Occurs in the Mitochondrial Matrix by Eclipsed Targeted Components of the Ubiquitination Machinery. Cells 11:4109. doi: 10.3390/cells11244109. PMID: 36552873 [5YIF = 6.1; Citations = 16]
4. Yip J, Wang S, Tan J, Lim TK, Lin Q, Yu Z, Karmon O, Pines O, Lehming N (2021) Fumarase affects the deoxyribonucleic acid damage response by protecting the mitochondrial desulfurase Nfs1p from modification and inactivation. iScience 24:103354. doi: 10.1016/j.isci.2021.103354. eCollection 2021 Nov 19. PMID: 34805801 [5YIF = 4.7; Citations = 9]
5. Silas Y, Singer E, Das K, Lehming N, Pines O (2021) A combination of Class-I fumarases and metabolites (α-ketoglutarate and fumarate) signal the DNA damage response in Escherichia coli. Proc Natl Acad Sci USA 118:e2026595118. doi: 10.1073/pnas.2026595118. PMID: 34083440 [5YIF = 10.6; Citations = 17]
6. Wang S, Ramamurthy D, Tan J, Liu J, Yip J, Chua A, Yu Z, Lim TK, Lin Q, Pines O, Lehming N (2020) Post-translational Modifications of Fumarase Regulate its Enzyme Activity and Function in Respiration and the DNA Damage Response. J Mol Biol 432:6108-6126. doi: 10.1016/j.jmb.2020.09.021. Epub 2020 Oct 12. PMID: 33058874 [5YIF = 4.9; Citations = 14]
7. Leshets M, Ramamurthy D, Lisby M, Lehming N, Pines O (2018) Fumarase is involved in DNA double-strand break resection through a functional interaction with Sae2. Curr Genet 64:697-712. doi: 10.1007/s00294-017-0786-4. Epub 2017 Dec 4. PMID: 29204698 [5YIF = 1.6; Citations = 36]
8. Leshets M, Silas YBH, Lehming N, Pines O (2018) Fumarase: From the TCA Cycle to DNA Damage Response and Tumor Suppression. Front Mol Biosci 5:68. doi: 10.3389/fmolb.2018.00068. eCollection 2018. PMID: 30090811 [5YIF = 4.5; Citations = 70]
9. Dik E, Naamati A, Asraf H, Lehming N, Pines O (2016) Human Fumarate Hydratase Is Dual Localized by an Alternative Transcription Initiation Mechanism. Traffic 17:720-732. doi: 10.1111/tra.12397. Epub 2016 May 6. PMID: 27037871 [5YIF = 4.4; Citations = 48]
10. Lim MX, Png CW, Tay CY, Teo JD, Jiao H, Lehming N, Tan KS, Zhang Y (2014) Differential regulation of proinflammatory cytokine expression by mitogen-activated protein kinases in macrophages in response to intestinal parasite infection. Infect Immun 82:4789-801. doi: 10.1128/IAI.02279-14. Epub 2014 Aug 25. PMID: 25156742 [5YIF = 3.1; Citations = 98]