Discussion
The heat shock response in E.coli increases the level of a regulator molecule that binds to promoter for RNA polymerase to increase the production of heat shock protein :
Answer: B
The regulator is the \(\sigma^{H}/\sigma^{32}\) factor.
In E. coli a rise in temperature rapidly increases the level of sigma 32, encoded by rpoH: its mRNA is translated more efficiently at high temperature, and the protein is stabilised because the chaperones that normally target it for degradation are busy with unfolded proteins. Sigma 32 binds RNA polymerase and directs it to heat shock promoters, increasing production of chaperones such as DnaK and GroEL and of proteases.
ppGpp and pppGpp are alarmones of the stringent response to amino acid starvation. Diadenosine polyphosphates such as AppppA accumulate under heat and oxidative stress, but they are small signalling nucleotides, not the factor that binds promoters together with RNA polymerase, and the last option names no such factor either.
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