Rassf Proteins as Modulators of Mst1 Kinase Activity.
Rassf1A/5 tumor suppressors serve as adaptor proteins possessing a modular architecture with the C-terminal consisting of a coiled-coil SARAH (Salvador-Rassf-Hippo) domain and the central portion being composed of Ras associated (RA) domain. Here, we investigate the effect of Rassf effectors on Mst1 function by mapping the interaction of various domains of Rassf1A/5 and Mst1 kinase using surface plasmon resonance (SPR). The results revealed that apart from the C-terminal SARAH domain of Mst1 which interacts to form heterodimers with Rassf1A/5, the N-terminal kinase domain of Mst1 plays a crucial role in the stabilization of this complex. In addition, SPR experiments show that the RA domains play an important role in fine-tuning the Mst1-Rassf interaction, with Rassf5 being a preferred partner over a similar Rassf1A construct. It was also demonstrated that the activity profile of Mst1 in presence of Rassf adaptors completely switches. A Rassf-Mst1 complexed version of the kinase becomes apoptotic by positively regulating Mst1-H2B mediated serine 14 histone H2B phosphorylation, a hallmark of chromatin condensation. In contrast, the heterodimerization of Mst1 with Rassf1A/5 suppresses the phosphorylation of FoxO, thereby inhibiting the downstream Mst1-FoxO signalling pathway.
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
Aruna
A
Bitra
GE Healthcare Life Sciences, John F Welch Technology Centre, Whitefield Road, Bangalore, 560048, India.
Srinivas
S
Sistla
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
Jessy
J
Mariam
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
Harshada
H
Malvi
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
Ruchi
R
Anand
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D004789:Enzyme Activation; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D011518:Proto-Oncogene Proteins; C411762:RASSF1 protein, human; C454042:RASSF5 protein, human; D025521:Tumor Suppressor Proteins; C082332:macrophage stimulating protein; D017228:Hepatocyte Growth Factor; D020559:Monomeric GTP-Binding Proteins