Characterisation of RNA guanine-7 methyltransferase (RNMT) using a small molecule approach

TY - JOUR

T1 - Characterisation of RNA guanine-7 methyltransferase (RNMT) using a small molecule approach

AU - Pearson, Lesley-Anne

AU - Petit, Alain-Pierre

AU - Mendoza Martinez, Cesar

AU - Bellany, Fiona

AU - Lin, De

AU - Niven, Sarah

AU - Swift, Rachel

AU - Eadsforth, Thomas

AU - Fyfe, Paul

AU - Paul, Marilyn

AU - Postis, Vincent

AU - Hu, Xiao

AU - Cowling, Victoria

AU - Gray, David

PY - 2025/2/17

Y1 - 2025/2/17

N2 - The maturation of the RNA cap involving guanosine N-7 methylation, catalyzsed by the HsRNMT (RNA guanine-7 methyltransferase (HsRNMT)-RAM (RNA guanine-N7 methyltransferase activating subunit (RAM) complex, is currently under investigation as a novel strategy to combat PIK3CA -mutant breast cancer. However, the development of effective drugs is hindered by a limited understanding of the enzyme’s mechanism and a lack of small molecule inhibitors. Following the elucidation of the HsRNMT-RAM molecular mechanism, we report the biophysical characterizsation of two small molecule hits. Biophysics, biochemistry and structural biology confirm that both compounds bind competitively with cap and bind effectively to HsRNMT-RAM in the presence of the co-product SAH, with a binding affinity (K D) of approximately 1 μM. This stabilisation of the enzyme-–product complex results in uncompetitive inhibition. Finally, we describe the properties of the cap pocket and provided suggestions for further development of the tool compounds.

AB - The maturation of the RNA cap involving guanosine N-7 methylation, catalyzsed by the HsRNMT (RNA guanine-7 methyltransferase (HsRNMT)-RAM (RNA guanine-N7 methyltransferase activating subunit (RAM) complex, is currently under investigation as a novel strategy to combat PIK3CA -mutant breast cancer. However, the development of effective drugs is hindered by a limited understanding of the enzyme’s mechanism and a lack of small molecule inhibitors. Following the elucidation of the HsRNMT-RAM molecular mechanism, we report the biophysical characterizsation of two small molecule hits. Biophysics, biochemistry and structural biology confirm that both compounds bind competitively with cap and bind effectively to HsRNMT-RAM in the presence of the co-product SAH, with a binding affinity (K D) of approximately 1 μM. This stabilisation of the enzyme-–product complex results in uncompetitive inhibition. Finally, we describe the properties of the cap pocket and provided suggestions for further development of the tool compounds.

UR - https://www.scopus.com/pages/publications/85219497568

U2 - 10.1042/BCJ20240608

DO - 10.1042/BCJ20240608

M3 - Article

C2 - 39869500

SN - 0264-6021

VL - 482

SP - 209

EP - 224

JO - Biochemical Journal

JF - Biochemical Journal

IS - 4

M1 - BCJ20240608

ER -