AMB: transcriptional regulation LES I

What does the promoter contain

The transcriptional start site (=6nt sequence at -10 and -35 of the ORF), located downstream (aka voor) de ORF dus

What seuquence is recognized by sigma factor

the TSS

In what ways can transcription initaion be regulated

through TF, chromatin or sigma factors (prok)

What is defined by the interaction between the promoter and the sigma factor

1. the starting point

2. the direction of transcription (depends on which strand)

3. intensisty (if promoter sequence contains mutation, it has lower affinity to the sigma factor)

How can diff genes be expressed at diff levels (2)

1. slightly diff sigma afctors

2. operon (eg lac operon)

what is the role of cAMP and CAP (in lac operon)

cAMP binds CAP, causes conformational change, activates CAP, which enhances affinity of the RNA holoenzyme (hele RNA complex) to the promoter DNA

why are most activators/repressor located closely to sigma factor

this allows direct physicial contact with RNA polymerase or the target DNA, so the activator/repressor can either facilitate transcription (by recruiting or stabilizing RNA pol) or block transcription

what is the advanatage of a 1 componnet system (name one example of a 1 component regulatory system)

that its fast, example = cAMP activated protein (CAP)

what are the advantages/disadvantages of a 2 component system (name one example of a 2 component regulatory system)

exmaple = NtrB & NtrC

disadvantage:

• requires ATP

advantage:

• it can amplify a signal (the sensory p kan meerdere regulatory p fosforyleren bijv)

• its more flexible (diff environmental signals can trigger the same response)

• they are physically seperated so they can independently evolve to fit new roles

what is transcribed by RNA pol I and what is the a-amantin sensitivity

transcribes precursors of rRNA (28S, 18S, 5.8S), it localizes to the nucleus and its insensitive to a-amantin

What is transcribed by RNA pol II and what is the a-amantin sensitivity

transcribes snRNAs (U1, 2, 4&5), miRNA and mRNA, its highly sensitive to a-amantin

qhat is transcribed by RNA pol III and what is the a-amantin sensitivity

transcribes small RNAs, so tRNAs and rRNAs, its moderately sensitive to a-amantin

What are the key structures IN RNA pol

• clamp, binds DNA

• ring, NTP travels through

• exit point, where DNA leaves

• bridge, pushes RNA pol to the next NTP

• rudder

what is the trigger loop and what is its connection to a-amantin

its what catalyzes the reaction of chemical binding of NTP & template base (waardoor RNA naar volgende base kan) it can be blocked by a-amantin (blocks elongation)

how many standard subunits are in RNA pol (die je zowel in prok als euk hebt)

5, 2 beta, 2 alfa and 1 omega

what is the CTD and how does it affect transcription

its a C terminal repeat sequence in the beta domain of RNA, its phosphorylation status is linked to transcription activity of genes (ser5 P → initiation, if ser 2 P → elongation, if unP → no transcription)