bacterial RNA polymerase and promoters Flashcards
what do you need to isolate RNA?
a good assay
what did Marianne Grunbery-Manago and Severo Ochoa discover?
first nucleic acid synthesizing enzyme (polynucleotide phosphorylase)
what were the characteristics of the first nucleic acid synthesizing enzyme?
It did not need a template
It did not need 4 different NDPs as substrate
It could make an RNA polymer if just 1 NDP was provided
The sequence of the product depended entirely on the ratio of substrate NDPs.
Real function = degradation NOT synthesis
how many functional parts do bacterial RNA polymerases have?
2
what are the 2 functional parts of bacterial RNA polymerase?
core enzyme and sigma subunit
describe the core enzyme;
usually 4 different subunits a2BB’w. Has catalytic function (can catalyze the formation of RNA phosphodiester bonds). The jaw is formed by both beta subunits and the base is the enzymes active site
what is the stoichiometry of the core enzyme?
a2BB’w
describe the sigma subunit;
that recognizes the promoter and is specific for the promoter sequence. Ultimately it specifies where RNA polymerase should initiate RNA synthesis.
what is it called when the RNA polymerase has both a core enzyme and a sigma subunit?
holoenzyme
what is the major consensus sequence?
TTGACA — 17+/-1 — TATAAT
how many domains does sigma 70 have?
4
what domains of sigma 70 recognize the sepecific regions of the consensus?
The -35 region is recognized by the 4.2 domain and the -10 region is recognized by the 2.4 domain
what does sigmas domain 4.2 fold into?
helix-turn-helix
what are the 2 domains in the alpha subunit?
N and C terminals
what do mutations in consensus elements do to RNA polymerase?
affect the ability of RNA polymerase holoenzymes to find and bind to its promoter. This can change the amount of RNA made
