Kobilka: “Structural insights into the dynamic process of G protein-coupled receptor activation.”

Science

Kobilka: “Structural insights into the dynamic process of G protein-coupled receptor activation.”

Dr. Brian Kobilka, the co-recipient of the 2012 Nobel Prize in Chemistry, spoke at the UW Health Sciences Center on Tuesday, Oct. 23.

  1. There are more than 1000 GPCRs, and they are involved in transduction of light, neurotransmitter, chemical, and hormone signals. GPCRs are an important target for drugs because their involvement in so many physiological functions . Kobilka’s work in GPCR structure and function has advanced our understanding of this complex family of receptors.
  2. Chemistry Nobel Prize Brian Kobilka at UW. GPCR activation talk to start in a few minutes #ChemNobel2012
  3. Dr. Kobilka was originally scheduled to speak in front of a reduced audience at the University of Washington Biochemistry weekly seminar series. After receiving the Nobel price in October 10th the venue changed to Hogness (capacity 482 seats).
  4. Brian Kobilka: I have never spoken in front of this many people before. UW Hogness Auditorium #ChemNobel2012
  5. Kobilka described the challenges of obtaining a protein crystal to study the structure for G-protein coupled receptors.
  6. He also talk about his recent work on the structure of b2 adrenaline
    receptor: “Recent crystal structures provide insights into inactive
    states of several GPCRs. Efforts to obtain an agonist-bound active-state
    GPCR structure have proven difficult due to the inherent instability of
    this state in the absence of a G protein. We generated a camelid
    antibody fragment (nanobody) to the human b2 adrenergic receptor (b2AR)
    that exhibits G protein-like behaviour, and obtained an agonist-bound,
    active-state crystal structure of the receptor-nanobody complex”
    (Rasmussen et al. Nature 2011)
  7. Nanobodies (variable region Ab from camelids) FTW! #kobilkaseminar
  8. Kobilka: Nanobodies from Llamas key for getting stable structure of our GPCR. We can track structural changes in GPCR cycle #ChemNobel2012
  9. ß2AR in several states. Agonist makes it more inestable, only G-protein stabilizes it in one state #Kobilkaseminar #ChemNobel2012
  10. Change in binding pocket of b2ar depends on g-protein coupling – not necessarily the ligand #kobilkaseminar
  11. From 2011 Nature paper: “Comparison with the inactive b2AR structure reveals subtle changes in the binding pocket; however, these small changes are associated with an 11A˚ outward movement of the cytoplasmic end of transmembrane segment 6, and rearrangements of transmembrane segments 5 and 7 that are remarkably similar to those observed in opsin, an active form of rhodopsin. This structure provides insights into the process of agonist binding and activation.”
  12. Small changes in binding pocket when ligand binds, big changes in TM helices #b2AR #kobilkaseminar
  13. Coupling between ligand binding and allosteric change pretty weak – dynamics #b2AR #kobilkaseminar
  14. Very strong agonists increase heterogeneity, unless there is nanobody bound #b2AR #kobilkaseminar
  15. From Kobilka’s lab: “The method that we developed to obtain crystals of the beta2AR
    (generating T4 lysozyme fusion proteins) has subsequently been used to
    crystallize twelve other GPCRs including the following structures from
    our lab: the M2 and M3 muscarinic receptors, the mu- and delta-opioid
    receptors, and the protease activated receptor (PAR1). These structures
    all represent inactive states of these GPCRs.”
  16. Muscarinic receptors have VERY closed binding pockets. #kobilkaseminar
  17. Efficacy determinants deep in pocket, conserved. Selectivity determinants more exposed #opiodreceptor #kobilkaseminar
  18. The muscarinic receptors don’t have accessible selectivity determinants. That makes it harder to develop drugs #kobilkaseminar
  19. Selectivity determinants that distinguish b2ar from b1ar also toward extraellular vestibule #kobilkaseminar
  20. Can explain selectivity of salmeterol by structure #kobilkaseminar
  21. Vestibular interactions influence selectivity, even if the ligand doesn’t contact those residues. #kobilkaseminar
  22. Muscarinic ligands also spend a long time hanging out by the extraellular residues. May be I pt for drug development #kobilkaseminar
  23. Q&A #KobilkaSeminar: how do you know structures reflect real states? functional data, many structures show coherent picture #ChemNobel2012
  24. Additional links: