Describe how a riboswitch can regulate the expression of vitamin B12 biosynthetic enzymes in response to B12 levels inside a cell using ALL the following terms correctly: mRNA, RBS, 16S rRNA, ssRNA.
A) The riboswitch interacts with mRNA and causes a conformational change in the ribosome binding site (RBS), preventing 16S rRNA from binding to the mRNA. This halts the production of B12 biosynthetic enzymes in response to low B12 levels.
B) The riboswitch binds to ssRNA, causing the mRNA to degrade, which in turn decreases the production of B12 biosynthetic enzymes when B12 levels are high.
C) The riboswitch forms a secondary structure in the mRNA that sequesters the RBS, preventing 16S rRNA from binding to the mRNA and halting translation. This occurs when B12 levels are high, reducing the production of B12 biosynthetic enzymes.
D) The riboswitch binds to the mRNA and inhibits its interaction with RBS, allowing 16S rRNA to bind and initiate translation of B12 biosynthetic enzymes, which occurs when B12 levels are low.