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REGULASI EKSPRESI PROTEIN

REGULASI EKSPRESI PROTEIN. Agustina Setiawati. Pendahuluan. DOGMA SENTRAL. Pada proses apakah ekspresi suatu gen diatur ? . Pendahuluan. Regulated genes Control cell growth and cell division.

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REGULASI EKSPRESI PROTEIN

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  1. REGULASI EKSPRESI PROTEIN AgustinaSetiawati

  2. Pendahuluan DOGMA SENTRAL

  3. Padaprosesapakahekspresisuatu gen diatur?

  4. Pendahuluan Regulated genes Control cell growth and cell division. Expression is regulated by the needs of the cell and the environment as needed (not continuously). Constitutive genes Continuously expressed. Housekeeping genes (such as those required for protein synthesis and glucose metabolism).

  5. OPERON • Kelompok gen yang ekspresinyadiaturolehinteraksioleh protein represordgn operator, site operator dan promoter • Kelompok gen yang letaknyaberadadiantarapromotordan terminator promoter repressor operator (controlling site) coding sequences terminator

  6. INDUCER and INDUCTION • Inducer = chemical or environmental agent that initiates transcription of an operon • Induction = synthesis of gene product(s) in response to an inducer

  7. Organization of an inducible gene containing an operon.

  8. GENE REGULATION

  9. Prokaryote • Lac Operon • TrpOperon

  10. LAC OPERON (Negative Regulation) • E. colimengekspresikan protein yang digunakanuntukmetabolismegula • Salahsatugula yang dimetabolismeadalah LAKTOSA • Laktosa= disakarida (glukosa+ galaktosa), sebagaisumberenergi. • Laktosabertindaksebagai INDUCER (denganberinteraksidengan protein represor) danmeningkatkanekspresi 3 enzim yang berperandalammetabolismelaktosa (1000-fold increase)

  11. LAC OPERON • LacI • . Mengekspresikan protein tetramer yang bertindaksebagairepresor • -galactosidase (lacZ) • memecahlaktosamenjadiglukosadangalaktosa. • mengubahlaktosamenjadiallolaktosa yang mengatur Lac operon • Lactose permease (lacY) • berperandalam transport laktosadalammembransitoplasma. • Transacetylase (lacA) • transfers an acetyl group from acetyl-CoA to -galactosides.

  12. Translation of lacoperon in wild type and mutant E. coli.

  13. Regulasi Lac operonoleh CAP

  14. Fig. 17.14, Base pair sequence of controlling sites, promoter, and operator for lac operon of E. coli.

  15. CAP memecahlaktosasaatkonsentrasiglukosarendahdanadalaktosa

  16. Trp OPERON • Trpoperonmenghasilkanberbagaimacamenzim yang berperandalambiosintesistriptofan (Trp) • Triptofanmerupakanasam amino yang diperlukanutkpertumbuhanbakteri • Triptofanbertindaksebagai repressor

  17. Trp OPERON • Jikaasam amino terdapatpada media, E.colimenggunakanasam amino tersebutsebelummensintesis. • Jika amino acids tidakadadalam medium, gen asam amino tersebutdiekspresikan are “turned on” (or expressed. • The tryptophan (Trp) operon of E. coli is one of the most extensively studied repressible operons.

  18. General organization of the Trpoperon of E. coli:

  19. Regulation of the trpoperon: • Two mechanisms regulate the trpoperon: • Repressor/operator interaction • Termination of initiated transcripts

  20. : Regulation of the trpoperon 1. Interaksi repressor/operator • Apabilatriptofanada, tryptophan terikatpada protein trpR. • Protein trpR binds to the trpoperator and mencegahtranskripsi • Represimengurangitingkattranskripsitrpoperon ~70-fold.

  21. Trp OPERON (Negative regulation)

  22. Regulation of the trpoperon: 2. AttenuasiTerminasitranskripsi • TranskripsiTrpoperonjgdikontrololeh by attenuasisehingga protein yang ditranslasikanmenjadilebihpendekdan non fungsional • Ketikaselkekurangantriptofan, Trpoperondiekspresikanmaksimaldansebaliknya. • Attenuation dapatmenurunkan level transkripsi 560-700 kali.

  23. Fig. 17.17a, Attenuation model in Trp starved cells.

  24. Fig. 17.17b, Attenuation model in Trp non-starved cells.

  25. KontrolEkspresi Protein Eukaryote dilakukanoleh: 1. Protein aktivatordanrepresor 2. Faktortranskripsi

  26. RegulasitranskripsiolehAktivator

  27. Aktivator yang terikatpada DNA binding site mengaktifkankomplekstranskripsi enzim RNA polimerasemengkatalisispembentukanfosfodiester

  28. Gene activator proteins recruit Chromatin modulation proteins to induce transcription

  29. Synergistic Regulation Transcription synergy

  30. Regulasitranskripsioleh protein represor

  31. Regulasitranskripsioleh protein represor

  32. RegulasitranskripsiolehFaktorTranskripsi • Protein yang dapatmengenali DNA padasekuenspesifikdanberperanmengaturtranskripsidisebut FAKTOR TRANSKRIPSI • Mekanismekerjafaktortranskripsi 1. menstabilkan/mendestabilkankompleksinisiasitranskripsi 2. meningkatkanreaksiasetilasi/deasetilasihiston 3. menarik protein aktivatorataurepresor

  33. Kerjafaktortranskripsidipengaruhiolehstruktursekundernya • Strukturtersebutmempengaruhiinteraksinyadengan DNA: 1. Helix-turn-Helix 2. Zinc finger 3. Leucine Zipper

  34. Helix-turn-Helix

  35. Zinc Finger

  36. Leucine Zipper

  37. Transcription Factor vs Activator

  38. Any question?

  39. TERIMA KASIH

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