Since September of 2015, Dr. Murat Alper Cevher is an Assistant Professor at Bilkent University, Department of Molecular Biology and Genetics. He did his undergraduate studies at Hunter College of the City University of New York (CUNY) and graduated in 2004. Later he joined the CUNY Biochemistry Ph.D. program and earned his doctoral degree in 2009. Following that, between 2010-2015 he carried-out his postdoctoral work at the Rockefeller University, a world class institute, in the laboratory of Dr. Robert G. Roeder, a pioneer in the field of transcription. Dr. Cevher is the recipient of the American Cancer Society postdoctoral fellowship (2013), the EMBO Installation Grant (2017), EMBO small grant (2018), TUBITAK 1001 (2019), EPIC-XS (2019), has five peer reviewed publications in high rank journals such as Nature Structural & Molecular Biology, EMBO J, Cancer Research, Wiley’s RNA Review and Nucleic Acids Research of which he is the first author in the first four of them.
Dr. Cevher is currently reconstituting the most critical transcriptional co-activator protein complex named the human Mediator. It is one of the largest existing protein complexes in nature and has 30-subunits. He is using the state-of-the-art Multibac baculovirus expression system to carry out this reconstitution. Part of his long-term goal is to build the entire Mediator complex and characterise its interaction surface with activators such as the Estrogen Receptor and structurally-functionally understand the mechanisms behind how these activators activate their target genes that lead to breast cancer.
The thirty-subunit human Mediator co-activator complex interacts with different transcription machinery as well as activators through its distinct subunits stabilizing the PIC (pre-initiation complex) formation. Our proposed work here is to 1 reconstitute the entire human Mediator complex, 2 to introduce deletion mutants, and understand which subunits of the Mediator are critical for these interactions, 3 understand the roles of the observed mutations on the isubunits in the development of certain diseases and later help in the design of certain therapeutics.
Transcriptional activation entails a series of factors, including the class designated as coactivators. Of these, the 30-subunit Mediator complex appears to be involved in the regulation of all RNA Polymerase II (Pol II) target genes and has emerged as the key integrative componant for transcription. Mediator action entails interactions of distinct subunits (for example, MED1 has been identified as one of the critical targets of nuclear receptors (NR), including ER whereas MED17 is a target of p53 and MED15 is a target of multiple activators, including SREBP1, that are involved in fatty acid metabolism). Due to the massive size of the Mediator and the resulting technical limitations in dissecting its mechanisms of action, detailed activation pathways entailing this coactivator have not yet been elaborated. However, because the subunits are organized into discrete head, middle, tail, and kinase modules, a systematic structure-function approach is nonetheless feasible.
Recently, we were able to reconstitute a functional 15-subunit human Mediator complex and define it as the “core” through over expression of the individual subunits of the head and middle modules in insect cells via the state-of-the-art Multibac baculovirus expression system (Cevher et al., 2014). Importantly, this reconstituted core displays significant basal and activator (p53) driven transcription activity, as well as strong interactions with some of the (but not all) componants of the transcriptional machinery. Through collaboration, using the newly developed cross-linking/mass-spectrometry (XLMS) method, we further show the 3D architecture of this core-human Mediator complex.
Our near-future plan is to build the human Mediator complex and fully understand the recruitment mechanisms of the entire transcription machinery that is dependent on the Mediator. We will additionally concentrate on revealing mechanisms underlying Mediator-NR dependent transcriptional activation concentrating mostly on ER. In the long run, this approach will be particularly helpful in investigating individual subunit mutations that have been correlated with various diseases focusing mostly on breast cancer.
Chen, Q., Cevher, M. A., Jiang, Q., Wang, S., Sun, X., Roeder, R. G., & Chen, M. (2022). LYL1 facilitates AETFC assembly and gene activation by recruiting CARM1 in t(8;21) AML. Proceedings of the National Academy of Sciences of the United States of America, 119(42), e2213718119.
Wu, A., Zhi, J., Tian, T., Cihan, A., Cevher, M. A., Liu, Z., David, Y., Muir, T. W., Roeder, R. G., & Yu, M. (2021). DOT1L complex regulates transcriptional initiation in human erythroleukemic cells. Proceedings of the National Academy of Sciences of the United States of America, 118(27), e2106148118.
Cevher M. A. (2021). Reconstitution of Pol II (G) responsive form of the human Mediator complex. Turkish journal of biology, 45(3), 253–261.
Mirkin, N., Fonseca, D., Mohammed, S., Cevher, M. A., Manley, J. L., & Kleiman, F. E. (2008). The 3' processing factor CstF functions in the DNA repair response. Nucleic acids research, 36(6), 1792–1804.