Molecular kinetics. Ras activation by SOS: allosteric regulation by altered fluctuation dynamics

Lars Iversen; Hsiung-Lin Tu; Wan-Chen Lin; Sune M Christensen; Steven M Abel; Jeff Iwig; Hung-Jen Wu; Jodi Gureasko; Christopher Rhodes; Rebecca S Petit; Scott D Hansen; Peter Thill; Cheng-Han Yu; Dimitrios Stamou; Arup K Chakraborty; John Kuriyan; Jay T Groves

doi:10.1126/science.1250373

Molecular kinetics. Ras activation by SOS: allosteric regulation by altered fluctuation dynamics

Science. 2014 Jul 4;345(6192):50-4. doi: 10.1126/science.1250373.

Authors

Lars Iversen¹, Hsiung-Lin Tu¹, Wan-Chen Lin¹, Sune M Christensen¹, Steven M Abel², Jeff Iwig³, Hung-Jen Wu¹, Jodi Gureasko³, Christopher Rhodes⁴, Rebecca S Petit¹, Scott D Hansen¹, Peter Thill⁵, Cheng-Han Yu⁶, Dimitrios Stamou⁷, Arup K Chakraborty⁸, John Kuriyan⁹, Jay T Groves¹⁰

Affiliations

¹ Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.
² Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
³ Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
⁴ Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA.
⁵ Department of Chemistry, MIT, Cambridge, MA 02139, USA.
⁶ Mechanobiology Institute, National University of Singapore, Singapore.
⁷ Department of Chemistry and Nano-Science Center, University of Copenhagen, Copenhagen, Denmark.
⁸ Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Department of Chemistry, MIT, Cambridge, MA 02139, USA. Department of Biological Engineering, MIT, Cambridge, MA 02139, USA. Ragon Institute of Massachusetts General Hospital, MIT, and Harvard, Cambridge, MA 02139, USA. Department of Physics, MIT, Cambridge, MA 02139, USA. Institute for Medical Engineering and Science, MIT, Cambridge, MA 02139, USA.
⁹ Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
¹⁰ Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. Mechanobiology Institute, National University of Singapore, Singapore. Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Berkeley Education Alliance for Research in Singapore, 1 Create Way, CREATE tower level 11, University Town, Singapore 138602. jtgroves@lbl.gov.

Abstract

Activation of the small guanosine triphosphatase H-Ras by the exchange factor Son of Sevenless (SOS) is an important hub for signal transduction. Multiple layers of regulation, through protein and membrane interactions, govern activity of SOS. We characterized the specific activity of individual SOS molecules catalyzing nucleotide exchange in H-Ras. Single-molecule kinetic traces revealed that SOS samples a broad distribution of turnover rates through stochastic fluctuations between distinct, long-lived (more than 100 seconds), functional states. The expected allosteric activation of SOS by Ras-guanosine triphosphate (GTP) was conspicuously absent in the mean rate. However, fluctuations into highly active states were modulated by Ras-GTP. This reveals a mechanism in which functional output may be determined by the dynamical spectrum of rates sampled by a small number of enzymes, rather than the ensemble average.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Allosteric Regulation
Catalytic Domain
Crystallography, X-Ray
Enzyme Activation
Humans
Kinetics
Nucleotides / chemistry
Protein Interaction Domains and Motifs*
Proto-Oncogene Proteins p21(ras) / agonists*
Son of Sevenless Protein, Drosophila / chemistry*
Son of Sevenless Protein, Drosophila / genetics

Substances

Nucleotides
Son of Sevenless Protein, Drosophila
Proto-Oncogene Proteins p21(ras)

Abstract

Publication types

MeSH terms

Substances

Grants and funding