Water Channels 2003 Chemistry Nobel Prize

1. Water Channels2003 Chemistry Nobel Prize Kristi McKee SFASU Fall 2003 Scientific Discovery

2. Importance of this Award • 70% of living systems are made up of water. • Have to have some type of mechanism to move water and important ions around.

3. Cell Membrane • The cell membrane is important in protecting the cells organelles from the environment and transporting nutrients in and waste out of the cell.

4. Cell Membrane • The cell membrane is made up of mostly phospholipidis and proteins.

5. Cell Membrane • Phospholipids have a hydrophilic and hydrophobic ends. • The phosphate head is charged while the carbon tail is not charged.

6. Phopholipid Structure

7. Cell Membrane • Three types of predominant proteins in the membrane: • Transport Proteins • Marker Proteins • Receptor Proteins

8. Cell Membrane • Transport Proteins – regulate transport and diffusion across membrane. There are two forms: • Carrier • Channel

9. Carrier Proteins • They do not extend the whole distance of membrane, instead move back and forth carrying nutrients and waste in and out.

10. Channel Proteins • Some act as a passive pore to allow diffusion of water and some other molecules. • Does not require energy.

11. History • 1890 Wilhelm Ostwald proposed the idea that electric signals were produced by ions moving in and out of the cell. He was awarded the Nobel Prize in 1909 for the discovery.

12. History • John Eccles, Alan Hodgkin and Andrew Huxley were able to show how potassium and sodium ions were involved in chemical cascades (i.e. eyes watering, muscles contracting) They were awarded a Nobel Prize in the 1963.

13. HIstory • Jens Skou awarded the Nobel Prize in Chemistry in 1997 for discovery of Sodium-Potassium Pumps.

14. History • In the 1970’s scientists were able to prove that some channels were specific to only particular type of ions. • However, no one had yet been able to see what a water channel actually does, how it looks.

15. Advance of Science • In the late 1980’s protein science had advanced for the study of molecular machinery of how proteins may work and function. • By 1992 scientists were able to identify which proteins were involved in channels.

16. Peter Agre

17. Peter Agre • BA in Chemistry 1970 Augsburg College • MD 1974 from Johns Hopkins University School of Medicine • 1974 – 75 Postdoctoral Fellowship Johns Hopkins Dept of Pharamacology

18. Agre • 1975 – 78 Internship and Residency at Case Western Reserve University Dept. of Medicine • 1978 – 80 Postdoctoral Fellowship At Univ. of N. Carolina at Chapel Hill Dept. of Medicine Hematology/Oncology Div. • 1980 – 81 Clinical Asst. Professor of Medicine Univ. of N. Carolina at Chapel Hill

19. Agre • 1980 – 81 Senior Clinical Research Scientist • 1981 – 83 Research Associate Johns Hopkins School of Medicine Dept. of Cell Biology/Anatomy and Medicine • 1984 – 93 Asst. Professor Johns Hopkins • 1990 – 94 Co-Director Office of Research Planning Dept. of Medicine

20. Agre • 1993 – present Professor Johns Hopkins School of Medicine Departments of Biological Chemistry and Medicine • 1996 – 1999 Director of John Hopkins Graduate Program in Cellular and Molecular Medicine (CMM) • 1999 – present Chair Advisory Board Johns Hopkins Graduate Program in CCM

21. Agre’s Work • In mid-1980’s he studied various proteins found in the membrane of red blood cells and also found one in the kidneys and was able to determine the peptide sequence and the corresponding DNA sequence. (CHIP28 28kDa)

22. Agre’s Work • Expressed the CHIP28 in Xenopus oocytes and placed in hypo-osmotic medium and noticed the cells swelling rapidly.

23. Agre’s Work • He tested his theory by a simple experiment by comparing two cells one with this protein and one without. When exposed to water the ones with the protein swelled and one without remain unchanged.

24. Agre’s Work

25. Agre’s Work • Also ran trials on artificial cells called liposome (type of soap bubble with water on inside and out) Also found the cells with the protein (CHIP28) inserted in membrane acted as previous cells. • He termed these channel proteins aquaporin, “water pore”.

26. Agre’s Work • From knowledge that Hg+2 blocks water movement in cells he was able to show the cells with the protein were also rendered inactive by the mercury ions. This finding made him believe that his discovery was actually a water channel.

27. Agre’s Work • In 2000 with other research scientists, he was able to show the first three-dimensional of an aquaporin (Aquaporin-1 from human red blood cell).

29. Agre’s Work

30. Phylogenetic Tree

31. The Other Half Roderick MacKinnon

32. Roderick MacKinnon • BS 1978 Brandeis University in Biochemistry • MD 1982 Tufts Medical School in Boston • 1985 Completed residency at Beth Israel Hospital, Harvard, board Certified in internal medicine.

33. MacKinnon • 1985 – 86 Postdoctoral Fellowship in Dept of Medicine at Beth Israel Hospital. • 1986 – 89 Postdoctoral Fellowship in Dept. of Biochemistry at Brandeis. • 1989 – 91 Asst Professor in Dept. of Cellular and Molecular Physiology, Harvard Medical School.

34. MacKinnon • 1991 – 92 Asst. Professor in Dept. of Neurobiology, Harvard Medical School. • 1992 received PEW Scholar in Biomedical Sciences and McKnight Scholars Award • 1995 Received Biophysical Society Young Investigator Award and was promoted to full Professor at Harvard Medical School Dept. of Neurobiology.

35. MacKinnon • 1996 – Present Professor in Laboratory of Molecular Neurobiology and Biophysics and Rockefeller University, New York City. Also an Investigator at the Howard Hughes Medical Institute. • 1999 Awarded Lasker Award for Basic Medical Research on work with ion channels.

36. MacKinnon • Took a new approach to try and crack the controversy of ion channel proteins. • First worked with scorpion toxin that was discovered to block potassium channels that lead to the discovery of the shaker gene.

37. MacKinnon • Discovered that potassium channels had to be tetramers by binomial statistics and the toxin experiments.

38. MacKinnon • Using his skills and the advancements of X-ray crystallography, MacKinnon taught himself the fundamentals and presented the structure of an ion channel in April of 1998 (KcsA from the bacterium Streptomyces lividans). • Also revealed how ion channel functions at an atomic level.

39. MacKinnon

40. MacKinnon • Two types of ion channels studied and discovered how they differentiated between ions: • Potassium channels • Sodium channels

41. MacKinnon • The channels had a selective “filter” in the P-loop, and a sensor to determine when to let the ions in and out of the cell. • Discovered in the potassium channel that the spacing between the K+ and the oxygen atoms in the filter and the sodium ions do not fit so they remain behind in the water solution.

42. MacKinnon

43. MacKinnon • Ion Channel GatingIon channel gating refers to opening and closing of the ion conduction pore in response to a specific stimulus. • Certain channels open when ligands bind (ligand-gated channels); others open in response to membrane voltage (voltage-gated channels).

45. MacKinnon • Studied diffusion-limited rates by analysis of ion conduction on potassium channels using K+ and Rb+ • Used Rb because they are know to penetrate K channels. • Found K+ ion is passed and rehydrated in approximently ten nanoseconds.

49. Channels • Types of channels • Water – They are responsible to transportation of water in and out of the cell. • Ion – Move ions in and out to conduct such things as signal cascades. • Aquaglyceroporins – Trasport glycerol and other small molecules across membrane.

50. Channels • There are now 11 different variants of these channels in the human body and more may still be discovered. • They are responsible for many reactions in the body one major function is done in the kidneys.