THE ARA OPERON
Biology 518 with Scot Hefty/susan Egan at University of Kansas
About this deck
By: crystal mccowen
Textbook:
Molecular Genetics of Bacteria (Snyder, Molecular Genetics of Bacteria)
Created: 2011-12-07
Size: 20 flashcards
Views: 6
Textbook:
Molecular Genetics of Bacteria (Snyder, Molecular Genetics of Bacteria)Created: 2011-12-07
Size: 20 flashcards
Views: 6
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1st example of
positive regulation
araBAD encodes
all enzs needed for metabolism of l-arabinose
# operons
2 (1 regulates AraC)
araC: transcription? encodes what?
transcribed from different promoter and in opposite direction than araBAD genes
encodes AraC (response regulator)
what is araI?
activator region (two half-sites: araI1 and I2)
where AraC binds (each AraC monomer binds one halfsite)
What is the inducer of this system?
arabinose (binds AraC)
describe +regulation by AraC. Result?
1. arabinoses bind both subunits of AraC dimer ==>aAraC dimer
2. aAraC dimer binds araI1I2 of DNA
3. aAraC then contacts RNA Pol to increase transcription initiation
====> INTERMEDIATE LEVEL OF EXPRESSION
Why is AraC unusual in its DNA-binding?
CTD binds direct repeat in DNA (instead of inverted repeat)
How do you get full level of araBAD expression?
CAP (w/cAMP) bound to CAP-binding site IN ADDITION TO aAraC dimer at araI1I2
type of regulation by AraC?
can be either + or -
describe -regulation by AraC
1. w/o arabinose, AraC still bound to DNA but one monomer bound to araI1, other at araO2
2. causes DNA to form loop==>prevents dimerization of AraC at araI2, AraC cant contact RNAPOL b/c its not at araI2 site, and loop prevents binding by RNA Pol
which is dominant: AraC or CAP?
AraC
-Glucose, -arabinose
off
-glucose, +arabinose
ON (fully on)
+glucose, -arabinose
off
+glucose, +arabinose
INTERMEDIATE!!!!!!
AraC family of transcription activators is defined by
100 AA DNA-binding domain
2 HTH motifs!!!
_% sequenced bacterial genomes have atleast 1 AraC family member. E.coli has ___
70
27
About this deck
By: crystal mccowen
Textbook: Molecular Genetics of Bacteria (Snyder, Molecular Genetics of Bacteria)
Created: 2011-12-07
Size: 20 flashcards
Views: 6
Textbook:
Molecular Genetics of Bacteria (Snyder, Molecular Genetics of Bacteria)Created: 2011-12-07
Size: 20 flashcards
Views: 6
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj