Complex allosteric regulation of mycobacterial inosine-5′-monophosphate dehydrogenase by purine nucleotides

0581637 - ÚOCHB 2024 RIV eng A - Abstract
Bulvas, Ondřej - Knejzlík, Zdeněk - Kouba, Tomáš - Pichová, Iva
Complex allosteric regulation of mycobacterial inosine-5′-monophosphate dehydrogenase by purine nucleotides.
[Discussions in Structural Molecular Biology /19./ and User Meeting of CIISB (Czech Infrastructure for Integrative Structural Biology) /6./. Nové Hrady, 23.03.2023-25.03.2023]
Method of presentation: Přednáška
Event organizer: Czech Society for Structural Biology
URL events: https://cssb.structbio.org/xix-discussions-in-structural-molecular-biology-and-6th-user-meeting-of-ciisb-czech-infrastructure-for-integrative-structural-biology/ 
R&D Projects: GA MŠMT(CZ) LX22NPO5103
Research Infrastructure: CIISB II - 90127
Institutional support: RVO:61388963
Keywords : allosteric regulation * inosine-5′-monophosphate dehydrogenase (IMPDH) * cryo-EM analysis
OECD category: Biochemistry and molecular biology
https://www.xray.cz/setkani/abst2023/630.htm

Inosine-5′-monophosphate dehydrogenase (IMPDH) is a crucial purine metabolism enzyme that is well established as a potential drug target against mycobacterial infections. However, most previous biochemical and structural studies were performed with IMPDH lacking its regulatory CBS domain, which binds allosteric regulators influencing the activity of IMPDH. This project aims to describe the allosteric regulation of full-length IMPDH and its underlying molecular mechanism. First, we isolated full-length and ΔCBS variants of IMPDH from Mycobacterium smegmatis and performed a detailed in vitro biochemical characterisation. Testing the impact of selected purine nucleotides on IMPDH activity indicated an unexpected regulatory effect of nucleotide ligands at biologically relevant concentrations. Next, to overcome problems with the X-ray crystallography approach, we utilised single particle cryo-EM analysis and, up to now, successfully obtained a series of datasets of IMPDH in complex with its allosteric regulators. Preliminary data suggest structural changes in the active/inhibited forms of IMPDH, which are triggered by the mode of binding of nucleotide ligands to the CBS domain. This might enable us to unravel the mechanism of interdomain crosstalk that leads to changes in the catalytic core of the enzyme. Such a mechanistic insight could contribute to the design of novel antimycobacterial IMPDH-targeting drugs.
Permanent Link: https://hdl.handle.net/11104/0349746