Cellular processes are carried out by macromolecules, mainly proteins and nucleic acids, which work as true nanoscopic machines that act in isolation or, more commonly, associated in macromolecular complexes. The dynamic nature of these complexes makes their study difficult, but learning how they work is critical to understand cellular function and the basis of certain diseases. In our group we combine X-ray crystallography and electron microscopy to study the three-dimensional structure of macromolecules and their complexes. Structural studies are complemented with other biochemical and biophysical techniques. These studies help us understand how nanoscale machines perform important cellular processes, as well as open avenues for the development of drugs against various diseases.
MAIN RESEARCH LINES
1. Eukaryotic transcription. Eukaryotic cells have three RNA polymerases (Pol) to transcribe their genetic content. Pol I synthesizes ribosomal RNA, Pol II produces all messenger RNA, and Pol III is responsible for transfer RNA. Coordination of these three enzymes is essential to maintain cellular homeostasis.
Pol I is a complex of 14 proteins with a total mass of 600 kDa, responsible for synthesizing the core of the ribosome. Regulation defects in Pol I transcription associate with problems in cell proliferation and, hence, with tumor development. We have determined the structure of this enzyme to 3 Å resolution using X-ray crystallography. The atomic structure explains fundamental properties of the enzyme, such as the incorporation of functional modules that must be recruited in other Pols, while suggesting a unique activation mechanism. These results were recently published in Nature and appeared in national and international media.
Pol III, consisting of 17 subunits with a total mass of 700 kDa, transcribes several small RNA genes such as transfer RNA. We have determined the structure of this macromolecular complex to 10 Å resolution using electron cryomicroscopy, both in the presence and absence of nucleic acids. These studies, in combination with native mass spectrometry experiments, have enabled us to understand the architecture and organization of this essential enzyme. These results were published in The EMBO Journal and RNA Biology.
2. Clinical applications against angiogenic diseases. Guillermo Giménez-Gallego was a member of the team that described the first angiogenic growth factor (FGF). Later he spent considerable effort in discovering inhibitors of FGF and at the end of 2010 he described a family of potent inhibitors derived of gentisic acid (GA). Meanwhile it was discovered that FGF induces angiogenesis as it triggers inflammation. The inhibitors of the GA family have shown, in the clinic, a remarkable capacity of controlling some inflammations, such as those causing macular degeneration.
Fernández-Tornero, C. . RNA polymerase I activation and hibernation: unique mechanisms for unique genes. Transcription. 9:248-254.
Sanz-Murillo, M., Xu, J., Belogurov, G.A., Calvo, O., Gil-Carton, D., Moreno-Morcillo, M., Wang, D., Fernández-Tornero, C. . Structural basis of RNA polymerase I stalling at UV light-induced DNA damage. Proceedings of the National Academy of Sciences of the United States of America. 115:8972-8977.
Torreira, E., Louro, J.A., Pazos, I., González-Polo, N., Gil-Carton, D., Duran, A.G., Tosi, S., Gallego, O., Calvo, O., Fernández-Tornero, C. . The dynamic assembly of distinct RNA polymerase i complexes modulates rDNA transcription. eLife. 6: art. no. e20832.
Canales, Á., Rösinger, M., Sastre, J., Felli, I.C., Jiménez-Barbero, J., Giménez-Gallego, G., Fernández-Tornero, C. . Hidden α-helical propensity segments within disordered regions of the transcriptional activator CHOP. PLoS ONE. 12: no. e0189171.
Garavís, M., González-Polo, N., Allepuz-Fuster, P., Louro, J.A., Fernández-Tornero, C., Calvo, O. . Sub1 contacts the RNA polymerase II stalk to modulate mRNA synthesis. Nucleic Acids Research. 45:2458-2471.
Moreno-Morcillo M, Taylor NM, Gruene T, Legrand P, Rashid UJ, Ruiz FM, Steuerwald U, Müller CW, Fernández-Tornero C . Solving the RNA polymerase I structural puzzle. Acta Cryst. D70:2570-2582
Basu RS, Warner BA, Molodtsov V, Pupov D, Esyunina D, Fernández-Tornero C, Kulbachinskiy A, Murakami KS . Structural basis of transcription initiation by bacterial RNA polymerase holoenzyme. J. Biol. Chem. 289:24549-24559
Torreira E, Seabra AR, Marriott H, Zhou M, Llorca O, Robinson CV, Carvalho HG, Fernández-Tornero C*, Pereira PJ* . The structures of cytosolic and plastid-located glutamine synthetases from Medicago truncatula reveal a common and dynamic architecture. Acta Cryst. D70:981-993
Fernández-Tornero C*, Moreno-Morcillo M, Rashid UJ, Taylor NM, Ruiz FM, Gruene T, Legrand P, Steuerwald U, Müller CW* . Crystal structure of the 14-subunit RNA polymerase I. Nature 502:644-649
Taylor NM, Glatt S, Hennrich ML, von Scheven G, Grötsch H, Fernández-Tornero C, Rybin V, Gavin AC, Kolb P, Müller CW . Structural and functional characterization of a phosphatase domain within yeast general transcription factor IIIC. J. Biol. Chem. 288:15110-15120
2015-2017. Ramón Areces Foundation
2014-2016. BFU2013-48374-P. Spanish Ministry of Economy and Competitiveness
2011-2013. BFU2010-16336. Spanish Ministry of Science and Innovation
2010-2016. Industrial Collaboration with PharmaMar