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Unraveling the resistance mechanism of PBP2A by SFX at XFELs

Methicillin-resistance Staphylococcus aureus (MRSA) is a major bacterial human pathogen that causes a wide variety of clinical manifestations. MRSA uses the penicillin binding protein 2a (PBP2a) as defense mechanism against beta-lactam antibiotics by an allosteric mechanism still not well known. We intend to use the unique properties of XFELs in conjunction with the mix-and-inject time-resolved serial femtosecond crystallography (TR-SFX) technique to determine the high-resolution X-ray structures of the intermediates involved in the large conformational change that propagates from the allosteric site to the catalytic site of the enzyme PBP2a. This will allow us to elucidate the unique allosteric regulation mechanism responsible for catalytic activity of PBP2A, to ultimately advance the design and development of novel antibiotics with higher efficacy.

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Selected references:

  1. Otero LH, et al., 2018. PNAS. 110:42, 16808-16813. doi: 10.1073/pnas.1300118110

  2. Mahasenan KV, et al., 2017. J Am Chem Soc.139(5):2102-2110. doi: 10.1021/jacs.6b12565. 

  3. Olmos JL, et al. 2018. BMC Biology 16(1):59. doi: 10.1186/s12915-018-0524-5

Deciphering the redox mechanism of NQO1: An anticancer target

Human NQO1 is a flavoenzyme essential for the antioxidant defense system, stabilization of tumor suppressors, and activation of quinone-based chemotherapeutics. NQO1 is over-expressed in tumors such as thyroid, breast, and lung, which makes this enzyme an attractive cancer target for drug discovery. In addition, proper NQO1 functionality and stability have been associated with other pathological situations, such as Alzheimer´s, and Parkinson´s disease. NQO1 develops its catalytic function by the “ping-pong” mechanism, which consists of two ordered steps: 1) Binding and oxidation of the electron donor NADH by FAD, reducing it to FADH2 and then NAD+ leaving the binding site; 2) Binding and reduction of a quinone substrate by FADH2. The main goal of our project will be to further understand the complex mechanism of NQO1 by determining the high-resolution crystallographic structures of the intermediates involved in the "pin-pong" mechanism by using the serial crystallography approach either at synchrotrons or at XFELs.  

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Selected references:

  1. Pey AL, et al., 2016. Curr Drug Targets, 17, 1506-1514. doi: 10.2174/1389450117666160101121610

  2. Anoz-Carbonell E, et al., 2020. Antioxidants, 9, 772. doi: 10.3390/antiox9090772

  3. Pacheco-Garcia JL, et al., 2021. Redox Biology 46, 102112. doi: 10.1016/j.redox.2021.102112

Serial crystallography at synchrotron light sources

The high demand for the SFX at XFELs to solve pressing current problems in biotechnology and biomedicine, together with the notorious scarcity of XFEL facilities, has caused the community of structural biologists to look for viable alternatives to increase its use. In this sense, recent technological advances in the field of synchrotrons themselves, with the production of more powerful and smaller X-ray beams, the advances in detector technology, as well as advances in sample injection methods, has facilitated the adaptation of this technique at synchrotron facilities, so-called SSX. As part of a collaborative project, we have, so far, implemented the SSX using the high-viscosity injector at several beamlines worldwide (ID-23-D and ID-14-B at APS; FMX at NSLS-II, and BL13-XALOC at ALBA) in order to make this technique more user friendly and accessible to more users in the near future

Selected references:

  1. Martin-Garcia JM, et al., 2022. JSR 29. https://doi.org/10.1107/S1600577522002508

  2. Martin-Garcia JM. 2021. Crystals. 11(5), 521. https://doi.org/10.3390/cryst11050521

  3. Martin-Garcia JM, et al., 2019. IUCrJ vol. 6,Pt 3 412-425. doi:10.1107/S205225251900263X

  4. Martin-Garcia JM, et al., 2017. IUCrJ vol. 4,Pt 4 439-454. doi:10.1107/S205225251700570X

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