@article {158504, title = {Cryo-EM structures of Mycobacterium tuberculosis imidazole glycerol phosphate dehydratase in the apo state and in the presence of small molecules.}, year = {2025}, abstract = {

Unlike humans,\ Mycobacterium tuberculosis\ (Mtb), the causative agent of human tuberculosis, has a\ de novo\ histidine-biosynthesis pathway. The enzyme imidazole glycerol phosphate dehydratase (IGPD), which catalyses the conversion of imidazole glycerol phosphate to imidazole acetol phosphate, has been studied extensively from various organisms and has become a major target for the development of antibacterial, antiweed and antifungal small molecules. In our previous studies, we have shown that in crystals IGPD forms a 24-mer oligomeric state in which the monomers are arranged in 432 symmetry. In order to gain insights into the oligomeric state of\ Mtb\ IGPD in solution, we determined cryogenic sample electron microscopy (cryo-EM) structures of apo IGPD at 2.2 and 3.1 {\r A} resolution. In addition, we also determined the cryo-EM structure of IGPD in the presence of 3-amino-1,2,4-triazole (ATZ) to 2.8 {\r A} resolution. The results of this work, which corroborate those from the crystallographic studies, indicate that IGPD forms a homo-oligomeric structure in solution comprising of 24 subunits. ATZ binds in the active-site pocket of the enzyme, which is located at the interface of three monomers and tethers 24 ATZ molecules. The results of this study suggest that cryo-EM, in addition to being a rapidly evolving and complementary imaging technology for elucidating 3D structures of biological macromolecules, can be useful in pinpointing the mode of binding small molecules of low mass (here \~{}85 Da) and mapping protein-ligand interactions, which could assist in the design of accurate (high-potency) inhibitors.

}, keywords = {cryo-EM; tuberculosis; histidine-biosynthesis pathway; imidazole glycerol phosphate dehydratase; drug discovery.}, doi = {https://doi.org/10.1107/S2053230X25004595}, url = {https://scripts.iucr.org/cgi-bin/paper?buy=yes\&cnor=ih5008\&showscheme=yes\&sing=yes}, author = {Raina, R and Kar, D and Singla, M and Tiwari, S and Kumari, S and Aneja, S and Kumar, V and Banerjee, S and Goyal, S and Pal, RK and Vinothkumar, KR and Biswal, B} } @article {106551, title = {Phosphoproteome of signaling by ErbB2 in ovarian cancer cells.}, journal = {Biochim Biophys Acta Proteins Proteom}, year = {2022}, month = {2022 Feb 11}, pages = {140768}, abstract = {

The gene for receptor tyrosine kinase ErbB2 is amplified in breast and ovarian tumours. The linear pathway by which signals are transduced through ErbB2 are well known. However, second generation questions that address spatial aspects of signaling remain. To address this, we have undertaken a mass spectrometry approach to identify phosphoproteins specific for ErbB2 using the inhibitors Lapatinib and CP724714 in ovarian cancer cells. The ErbB2 specific proteins identified in SKOV-3 cells were Myristoylated alanine-rich C-kinase substrate, Protein capicua homolog, Protein peptidyl isomerase G, Protein PRRC2C, Chromobox homolog1 and PRP4 homolog. We have evaluated three phosphoproteins PKM2, Aldose reductase and MARCKS in SKOV-3 cells. We observed that PKM2 was phosphorylated by EGF but was not inhibited by Lapatinib and CP724714. The activity of aldose reductase in reducing NADPH as a substrate was significantly higher in EGF stimulated cells which was inhibited by Lapatinib and CP724714 but not by Geftinib (EGFR inhibitor). MARCKS was phosphorylated on stimulation of SKOV-3 cells with EGF that was inhibited by Lapatinib and CP724714 which was dependent on the kinase activity of ErbB2. These results have identified phosphoproteins that are specific to ErbB2 which have not been previously reported and sets the basis for future experiments.

}, issn = {1878-1454}, doi = {10.1016/j.bbapap.2022.140768}, author = {Sidhanth, C and Bindhya, S and Krishnapriya, S and Manasa, P and Shabna, A and Alifia, J and Patole, C and Kumar, V and Garg, M and Ganesan, T S} }