PLS 623: Physiology of Plants II Spring Semester 2014

1. PLS 623: Physiology of Plants IISpring Semester 2014 Jan Smalle (jsmalle@uky.edu)

2. Journal club format Why? Practice how to prepare papers and express ideas correctly. Training in science debate. Practice presentation: research seminar.

5. TARGETED PROTEIN DEGRADATION Lectures: January 15, 17 Exam: January 22

8. Central dogma of genetics

9. Central dogma of genetics Regulation of an organisms differentiation and responses to the environment are the result of changes in gene expression. OLD THEORY: Regulation of gene expression is predominantly controlled at the transcription level. NEW THEORY: Regulation of gene expression is the result of a combination of protein synthesis (transcription/translation) and protein degradation controls.

10. EXAMPLE Day/night cycle: day light activates gene expression Light PROTEIN DNA RNA Light responses

11. Dark DNA RNA PROTEIN ???? Light responses ? Day/night cycle: During night time, light-inducible genes are down-regulated However, regulatory proteins that promote the light response need to be removed in the dark. Otherwise, they would interfere with the dark response.

12. Photomorphogenesis HY5: a transcriptional activator of photomorphogenic development Light intensity 5 days old Arabidopsis seedlings grown under a range of light intensities Western blot using HY5 antiserum (Osterlund et al., 2000)

13. Ethylene signaling EIN3: a transcriptional activator of ethylene responses Western blot using EIN3 antiserum 4 days old Arabidopsis seedlings grown in the dark on a range of concentrations of the ethylene precursor ACC (Guo and Ecker, 2003)

14. PRO + PROTEIN Q O O O I I I I P P P P T T T T N N N N R R R R E E E E Proteolysis Errors: Misfolded: Cleaved: AA supply: Regulation: T PRQTEIN PRO PROPROTEIN PROTEIN PROTEIN EIN PROTEIN

15. Non-specific Proteolysis PROTEIN PROTEIN PROTEIN PROTEIN PROTEIN PROTEIN O O O O O O I I I I I I P P P P P P T T T T T T N N N N N N R R R R R R E E E E E E

16. Specific or Targeted Proteolysis PROTEIN O I P T N R E PROTEIN PROTEIN PROTEIN PROTEIN PROTEIN

17. Conditional Proteolysis PROTEIN O I P T N R E DARK PROTEIN PROTEIN PROTEIN PROTEIN PROTEIN

18. Conditional Proteolysis O I P T N R E Many cases of conditional proteolysis involve secondary modifications of target proteins. For example: phosphorylation/dephosphorylation. * Kinase PROTEIN PROTEIN Phosphatase

19. Conditional Proteolysis O I P T N R E Many cases of conditional proteolysis involve secondary modifications of target proteins. For example: phosphorylation/dephosphorylation. * Kinase PROTEIN PROTEIN Phosphatase

20. Conditional Proteolysis O I P T N R E Signal Receptor X? * PROTEIN PROTEIN PROTEIN PROTEIN PROTEIN PROTEIN

24. [Vierstra, 2003 TIPS]