Regulation of mRNA translation is a major mechanism that maintains stoichiometric availability of ribosomal proteins (r-proteins) to rRNA molecules they bind to. Translational regulation is facilitated by general occurrence of the r-protein genes in several operons containing multiple genes. Which one of the following represents an established mechanism to ensure optimal production of the r-proteins in E. coli, when the r-proteins accumulate in free form (molar excess over rRNA).
The free r-protein(s) often bind to corresponding DNA sequences and activate transcription of rRNA genes to increase RNA availability.
The free r-protein(s) bind to RNA polymerase and represses transcription of the r-protein genes to decrease the availability of their mRNAs.
The free r-protein(s) bind to the mRNA(s) and downregulate their translation.
The free r-protein(s) bind free NTPs which then activate their cryptic ribonuclease activity leading to the degradation of their mRNAs.
Regulation of mRNA translation can be important as an additional layer of control on top of gene transcription, in which RNA binding proteins (RBPs) can modify translation of a set of transcripts to the cell’s actual protein requirement.
Therefore statement 3 is correct.Hence, the correct answer is option 2.