Chemistry 2100 Chapter 26
The Central Dogma The central dogma of molecular biology: –Information contained in DNA molecules is expressed in the structure of proteins. –Gene expression is the turning on or activation of a gene. 2
transcription
Transcription The architecture of yeast RNA polymerase II. Transcription of DNA (helical structure) into RNA (red) is shown. The template strand of DNA (blue) and the coding strand (green) and also shown. 6
Transcription Organization and transcription of a split eukaryote gene. 7
Why detect Transcription Factor targets? Transcription factors are medically relevant – ~10% of human genes – Crucial roles in development and cell life cycle – Misregulation and mutation cause disease – Critically, most cancers involve TF overactivity Darnell, Nature Reviews Cancer 2, 740 (2002)
Traditional methods for Transcription Factor detection Expression Microarrays Gel Shift Assays The challenge: Most of these methods are indirect, slow (hours), or can’t differentiate active and inactive protein. Western Blots
Bio-mimicry is a powerful motivation Velcro: inspired by burrs Conformation Switching Probes Marvin J S et al. PNAS 1997;94:
Optical Conformation Switching TF Switch Sensors
Rationally Tuning TF Sensors % switches open KS = 10 KS = 1 KS = 0.1 KS = 0.01 KS = KS = [ ] KS [target] KD (1+ KS) + KS [target] % switches open = KD = [ ] Target [M]
TF Beacon Actual Performance
Quantitative Detection in 4 easy steps
initiation
elongation
A – U – G – U – U – U – G – U – C – A – G – U..... mRNA tRNA peptide Met –––– Phe –––– Val –––– Ser.... (5') U – A – C – A – A – A – C – A – G – U – C – A
AU CU
Pyrimidine Dimers from UV
The Genetic Code 33
DNA T – A – C – A – A – A – C – A – G – T – C – A..... A – T – G – T – T – T – G – T – C – A – G – T..... (3') (5') peptide Met –––– Phe –––– Val –––– Ser.... A – U – G – U – U – U – G – U – C – A – G – U..... mRNA (5')
DNA T – A – C – A – A – A – C – A – G – T – C – A..... A – T – G – T – T – T – G – T – C – A – G – T..... (3') (5') peptide Met –––– Phe –––– Val –––– Ser.... A – U – G – U – U – U – G – U – C – A – G – U..... mRNA (5')
DNA T – A – C – A – A – A – C – A – G – T – C – A..... A – T – G – T – T – T – G – T – C – A – G – T..... (3') (5') peptide Met –––– Phe –––– Val –––– Ser.... A – U – G – U – U – U – G – U – C – A – G – U..... mRNA (5')
DNA T – A – C – A – A – A – C – A – G – T – C – A..... A – T – G – T – T – T – G – T – C – A – G – T..... (3') (5') peptide Met –––– Phe –––– Val –––– Ser.... A – U – G – U – U – U – G – U – C – A – G – U..... mRNA (5')
peptide Met –––– Phe –––– Val –––– Ser.... A – U – G – U – U – U – G – U – C – A – G – U..... mRNA (5') peptide Met –––– Phe –––– Asp –––– Ser.... A – U – G – U – U – U – G – A – C – A – G – U..... mRNA (5') Mutations
point substitution mutation peptide Met –––– Phe –––– Val –––– Ser.... mRNA (5') peptide Met –––– Phe –––– Asp –––– Ser.... A – U – G – U – U – U – G – A – C – A – G – U..... mRNA (5') A – U – G – U – U – U – G – U – C – A – G – U – A....
point substitution mutation peptide Met –––– Phe –––– Val –––– Ser.... mRNA (5') peptide Met –––– Phe –––– Asp –––– Ser.... A – U – G – U – U – U – G – A – C – A – G – U – A.... mRNA (5') A – U – G – U – U – U – G – U – C – A – G – U – A....
point substitution mutation peptide Met –––– Phe –––– Val –––– Ser.... A – U – G – U – U – U – G – U – C – A – G – U – A.... mRNA (5') peptide Met –––– Phe ––– Asp ––– Ser.... A – U – G – U – U – U – G – A – C – A – G – U – A.... mRNA (5')
peptide Met –––– Phe –––– Val –––– Ser.... mRNA (5') frameshift mutation peptide Met –––– Phe –––– Val –––– Val.... A – U – G – U – U – U – G – U – C – A – G – U – A.... mRNA (5') A – U – G – U – U – U – G – U – C – A – G – U – A....
peptide Met –––– Phe –––– Val –––– Ser.... mRNA (5') frameshift mutation peptide Met –––– Phe –––– Val –––– Val.... A – U – G – U – U – U – G – U – C – A – G – U – A.... mRNA (5') A – U – G – U – U – U – G – U – C – A – G – U – A....
peptide Met –––– Phe –––– Val –––– Ser.... mRNA (5') frameshift mutation peptide Met –––– Phe –––– Val –––– Val.... A – U – G – U – U – U – G – U – C – A – G – U – A.... mRNA (5') A – U – G – U – U – U – G – U – C – A – G – U – A....
PCR Polymerase Chain Reaction
DNA Fingerprinting
DNA Sequencing
Shotgun Sequencing
Electrochemical Sequencing
Recombinant DNA
Gene Therapy