核酸特性結構和功能英文版

1、會計學1核酸特性結構和功能英文版核酸特性結構和功能英文版第1頁/共54頁“Chromatin is the last refuge of scoundrels”第2頁/共54頁A Mitotic Human ChromosomeDNA length: 4.6 x 107 bp = 1.5 cm Chromosome length: 2 mCompaction ratio = 80001第3頁/共54頁ChromatinDNA CompactionDNA AccessibilityChromatinRemodelingMachinesNIH第4頁/共54頁Basic Unit of Chroma

2、tin Structure: Polynucleosome2Compaction ratio = 6第5頁/共54頁Limited Micrococcal Nulcease Digestion of Chromatin Generates a 200 bp Ladder3第6頁/共54頁H1H1H1H1H1H1Micrococcal Nuclease Digestion TimeMononucleosomeChromatosomeCore ParticleLinker DNA (variable)Operational Definititions of Nucleosome Particles

3、Chromatin4第7頁/共54頁The 30 nm Chromatin Fiber5Compaction ratio = 50第8頁/共54頁A Mitotic Human ChromosomeDNA length: 4.6 x 107 bp = 1.5 cm Chromosome length: 2 mCompaction ratio = 8000130 nm filament第9頁/共54頁Nuclear Scaffold/MatrixDNA Loops (5-200 kb)SAR/MAR6第10頁/共54頁The Nucleosome146 bp DNA 2X H3, H4, H2A

4、, H2BH4H2BH2AH3Not in Handout第11頁/共54頁 Identities = 74/82 (90%), Positives = 79/82 (96%)Query: 22 ILRDNIQGITKPAIRRLARRGGVKRISGLIYEEVRAVLKSFLESVIRDSVTYTEHAKRKT 81 +LRDNIQGITKPAIRRLARRGGVKRISGLIYEE R VLK FLE+VIRD+VTYTEHAKRKTSbjct: 21 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 80Query

5、: 82 VTSLDVVYALKRQGRTLYGFGG 103 VT+DVVYALKRQGRTLYGFGGSbjct: 81 VTAMDVVYALKRQGRTLYGFGG 102Blast Search with S. cerevisiae Histone H4Query: S. cerevisiaeSubject: H. sapiensNot in Handout第12頁/共54頁MW Chromosomal Proteins200,00036,00097,00066,00055,00031,00021,00014,000116,000H4H2AH2B/H3Histones are Low

6、MW Chromosomal Proteins7第13頁/共54頁Domain Structure of Histones123L1L2NCCore Domain8第14頁/共54頁H2BH2AH3H42312312312319L1L2N第15頁/共54頁H3H410第16頁/共54頁4 helix-bundleH3H4H3H411第17頁/共54頁4 helix-bundleH4H2BH2A12第18頁/共54頁H4H2BH2AH3Not in Handout第19頁/共54頁H4H2BH2AH3Diameter = 110 A13第20頁/共54頁H4H2BH2AH3Width = 45

7、A14第21頁/共54頁H4H2BH2AH315Axis of dyad symmetry第22頁/共54頁Histone CoreTilt+RollTilt-Roll15ATiltRoll第23頁/共54頁H2BH2AL1-L2Minor groove 1- 1Minor grooveL1-L2Minor groove16第24頁/共54頁H2BH2ANot in HandoutDNA entryDNA exit第25頁/共54頁N-term helixH2BH2AH3Not in HandoutDNA entryDNA exit第26頁/共54頁N-term helixN-term hel

8、ixH2BH2AH3Not in HandoutDNA entryDNA exit第27頁/共54頁Energetic and TopologicalConsequences of DNA Wrapping第28頁/共54頁Basepair:151015HistoneCoreTranslational and Rotational Positioning第29頁/共54頁Basepair:151015HistoneCoreTranslational and Rotational Positioning第30頁/共54頁Basepair:151015HistoneCoreTranslationa

9、l and Rotational PositioningARECOUPLED!第31頁/共54頁19第32頁/共54頁Are Nucleosomes “Positioned?”1. Sequence at Unique Position2. Micrococcal Nuclease Digest3. Restriction Digest4. Southern BlotDiscrete Band PositioningSmear Random Orientation 17第33頁/共54頁Implications of Translational Positioning18第34頁/共54頁N-

10、ARTKQTARKSTGGKAPRKQLATKAARKSAPATGGVKKPHRYRPGTVALREIRRYQKSTE- H3N-SGRGKGGKGLGKGGAKRHRKVLRDNIQ - H4N-SGRGKQGGKTRAKSKTRSSRAGL- H2AN-SDPAKSAPAAKKGSKKAVTKTQKKDGKKRRKSRKES- H2BH3 -ERA-CH4 -RTLYGFGG-CH2A -ELNKLLGGVTIAQGGVLPNIQSVLLPKKTESSKSTKSK-CH2B -PGELAKHAVSEGTKAVTKYTSAK-CCore Core Histones Have Variable

11、 Length Tails20第35頁/共54頁H4H2BH2AH3H3 N-terminusH3 N-terminus21第36頁/共54頁H4H2BH2AH3H2B N-terminus22第37頁/共54頁H4H2BH2A+_23第38頁/共54頁N-SGRGKGGKGLGKGGAKRHRKVLRDNIQ -H4PAcAcAcAcN-ARTKQTARKSTGGKAPRKQLATKAARKSAPATGGVKKPHRYRPGTVALREIRRYQKSTE- H3Core PP1028AcAcAcAcAcAcN-SGRGKQGGKTRAKSKTRSSRAGL-H2APAcAcN-SDPAKSA

12、PAAKKGSKKAVTKTQKKDGKKRRKSRKES-H2BPAcAcAcAcAcAc23ANewly-synthesized histonesMMMMMK79ActiveregionInactiveRegion (heterochromatin, X-inactivation)ActiveregionMitosis(Aurora B)SSN6/TUP1第39頁/共54頁?“Beads on a String”30 nm Filament24Low saltHigh saltHow does chromatin become compacted?第40頁/共54頁第41頁/共54頁His

13、tone H5 reduces salt requirement for chromatin compaction25第42頁/共54頁Helix III - Major groove bindingLoop(Secondary DNA binding site)Globular domain of Histone H5“winged helix-turn-helix domain”26第43頁/共54頁NCCCCCC26Zhou et al., 1998 Nature 395, 402第44頁/共54頁The Solenoid Model for the 30 nm Fiber26AHist

14、one H1第45頁/共54頁The 30 nm Chromatin Fiber5Compaction ratio = 50第46頁/共54頁CondensinsCondensins Are Required for Mitotic ChromosomeCondensationHirano and Mitchison, Cell 79, 449Condensin-DepletedMock-DepletedHirano et al., Cell 89, 51127第47頁/共54頁“Chromatin is the last refuge of scoundrels”第48頁/共54頁A Mit

15、otic Human ChromosomeDNA length: 4.6 x 107 bp = 1.5 cm Chromosome length: 2 mCompaction ratio = 80001第49頁/共54頁The Nucleosome146 bp DNA 2X H3, H4, H2A, H2BH4H2BH2AH3Not in Handout第50頁/共54頁H2BH2AL1-L2Minor groove 1- 1Minor grooveL1-L2Minor groove16第51頁/共54頁Basepair:151015HistoneCoreTranslational and Rotational Positioning第52頁/共54頁Basepair:151015HistoneCoreTransla