Transcription Termination in Prokaryotes — Transcript

Full transcript

1. 0:00Oh in the series of videos we have been
2. 0:04discussing about the transcription in
3. 0:06prokaryotes and now in this video we'll
4. 0:09be discussing about the termination of
5. 0:11transcription in prokaryotes the
6. 0:14termination of transcription in e.coli
7. 0:16or in prokaryotes proceeds in two ways
8. 0:18either it's row independent termination
9. 0:21or it's row dependent termination row
10. 0:23here is the protein that means in one
11. 0:26case there is no involvement of pro
12. 0:27protein well as in other case there is
13. 0:30involvement of pro protein in row
14. 0:32independent termination the physical
15. 0:34modified structure of RNA transcript
16. 0:36terminates the transcription whereas in
17. 0:39case of row dependent termination the
18. 0:41helices protein row protein terminates
19. 0:43the transcription the second point we
20. 0:47see here is that in row independent
21. 0:49termination the hairpin loop like
22. 0:51structure pulls off RNA transcript from
23. 0:53there RNA polymerase complex thereby
24. 0:57terminating the transcription as you can
25. 0:59see in this diagram the hairpin loop
26. 1:01like structure comes into action in row
27. 1:03independent termination now looking at
28. 1:07the Road appendant termination the
29. 1:08helicase protein which is the hexameric
30. 1:10protein has structure like this it binds
31. 1:13to the right side on RNA transcript and
32. 1:15gets to the polymerase enzyme where it
33. 1:18terminates the transcription and this
34. 1:20row protein is ATP dependent protein
35. 1:24now let's discuss a row independent
36. 1:26termination in detail first in this
37. 1:28diagram we can see we have the DNA
38. 1:30molecule having RNA polymerase attach it
39. 1:33to it this RNA polymerase enzyme works
40. 1:36on the lower strand that's the template
41. 1:38strain and we had this RNA molecule
42. 1:41being synthesized it here and here in
43. 1:43this diagram we can see we had the
44. 1:44termination site here having a poly ATP
45. 1:48or editing and timing peers to see how
46. 1:51he open loop homes we see in the next
47. 1:54step the RNA molecule which is getting
48. 1:56synthesized it has got couple of GC
49. 1:58regions like GC g GC c g so what happens
50. 2:04with these GC rich regions is that the
51. 2:06GC bases peers with each other and form
52. 2:09the hairpin loop like structure shown in
53. 2:12the diagram
54. 2:13actually this lupone's due to
55. 2:15palindromic sequences on RNA transcript
56. 2:19here in this diagram it is these two
57. 2:21regions which come together and poms
58. 2:23loop now this loop reduces the length of
59. 2:26rna-dna hybrid so from this structure
60. 2:29the RNA will get a physical traction but
61. 2:32to pull out RNA molecule from the
62. 2:33polymerase machinery it needs a weak
63. 2:36link we should break easily and this is
64. 2:40provided by a tear each reagent DNA
65. 2:42white template strand having poly I'd
66. 2:45mean and transcribes poly us all in the
67. 2:48RNA chain so this region au base pair is
68. 2:52the weak point where from the
69. 2:54transcription is terminated easily when
70. 2:56the hairpin loop like structure forms
71. 2:58and in the end we get RNA molecule out
72. 3:01of the polymerase complex easily as
73. 3:03shown in the diagram so this is how ro
74. 3:07independent termination works now let's
75. 3:09see how ro dependent termination is
76. 3:11drawn in this diagram we have DNA
77. 3:14molecule having RNA polymerase attached
78. 3:16a trait which has synthesized RNA
79. 3:18molecule as shown in the diagram this
80. 3:21nascent RNA molecule has one interesting
81. 3:23site on it called the rut site ROH
82. 3:27utilization site to this rut site the ro
83. 3:31helices protein binds and starts moon
84. 3:34towards the transcription machinery RNA
85. 3:36polymerase as shown in the animation and
86. 3:39it must be noted that this hill case
87. 3:41uses energy from the ATP hydrolysis when
88. 3:45this helices reaches the end of RNA
89. 3:47molecule it encounters that DNA RNA
90. 3:49duplex and this being the helicase
91. 3:52enzyme unwinds the duplex easily and
92. 3:55finally our net transcript is released
93. 3:57from the complex this way ro dependent
94. 4:01termination is driven in the e.coli so
95. 4:04this is all about termination of
96. 4:06transcription in prokaryotes I hope you
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