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Published on: April 2, 2014

Secondary structure of mouse and rabbit alpha- and beta-globin mRNAs: differential accessibility of alpha and beta

G N Pavlakis, R E Lockard, N Vamvakopoulos

    Cell
    |January 1, 1980
    PubMed

    Insights

    Investigating mouse and rabbit globin messenger RNAs revealed differences in initiator codon accessibility. Beta-globin mRNA

    Area of Science:

    • Molecular Biology
    • Genetics
    • Biochemistry

    Background:

    • Messenger RNAs (mRNAs) encode proteins, and their translation initiation is a critical regulatory step.
    • Alpha- and beta-globin mRNAs are essential for hemoglobin synthesis, with differential expression observed in various conditions.
    • The secondary structure of mRNA can influence translation efficiency and initiation rates.

    Purpose of the Study:

    • To establish the nucleotide sequence of mouse alpha- and beta-globin messenger RNAs (mRNAs).
    • To analyze the secondary structures of mouse and rabbit alpha- and beta-globin mRNAs.
    • To investigate the accessibility of the AUG initiator codon in alpha- and beta-globin mRNAs and its correlation with translation initiation rates.

    Main Methods:

    • Sequencing of the 5' terminus of mouse alpha- and beta-globin mRNAs.
    • Analysis of mRNA secondary structures using 5' 32P end-labeled mRNAs as substrates.
    • Enzymatic probing with S1 and T1 nucleases to identify single-stranded regions.

    Main Results:

    • The AUG initiator codon in beta-globin mRNA (both mouse and rabbit) is accessible to S1 and T1 nucleases, indicating it is in an exposed region.
    • The AUG initiator codon in alpha-globin mRNA (both species) is inaccessible to these nucleases, suggesting it is buried or base-paired.
    • Translation initiation rates for beta-globin mRNA are 30-40% faster than for alpha-globin mRNA in rabbit reticulocyte lysates.

    Conclusions:

    • The accessibility of the AUG initiator codon correlates with the rate of protein synthesis initiation.
    • Exposed AUG codons in beta-globin mRNA facilitate faster translation initiation compared to the less accessible AUG in alpha-globin mRNA.
    • mRNA secondary structure plays a significant role in regulating globin gene expression at the translational level.

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