Bacterial sRNAs can bind to mRNAs through complementary binding to regulate gene expression. What determines whether the sRNA/mRNA binding will promote or repress mRNA translation?

Verified step by step guidance

1. Understand that bacterial sRNAs regulate gene expression by binding to mRNAs through complementary base pairing, affecting translation.
2. Recognize that the outcome of sRNA/mRNA binding depends on the specific binding site on the mRNA, such as the ribosome binding site (RBS) or other regulatory regions.
3. If the sRNA binds near or overlaps the ribosome binding site, it can physically block ribosome access, leading to repression of translation.
4. Alternatively, sRNA binding can stabilize the mRNA or alter its secondary structure to expose the ribosome binding site, thereby promoting translation.
5. Therefore, the key factor determining promotion or repression is the location and effect of the sRNA binding on the mRNA's accessibility to the ribosome and its stability.

Key Concepts

sRNA-mRNA Complementary Binding

Small RNAs (sRNAs) regulate gene expression by base-pairing with target mRNAs through complementary sequences. This binding can affect mRNA stability or translation efficiency depending on the binding site and interaction strength.

Mechanisms of Translation Regulation by sRNAs

sRNA binding can either block the ribosome binding site (RBS) to repress translation or expose the RBS by altering mRNA structure to promote translation. The outcome depends on where the sRNA binds relative to key regulatory regions on the mRNA.

Role of RNA Chaperones and mRNA Structure

Proteins like Hfq assist sRNAs in binding mRNAs and influence the regulatory effect. Additionally, the secondary structure of mRNA affects accessibility of binding sites, determining whether sRNA binding stabilizes or destabilizes the mRNA or alters translation.