Evolutionary conserved multiprotein complexes interact with the 3' untranslated region of histone transcripts

Area of Science:

• Molecular Biology
• Gene Regulation
• RNA Metabolism

Background:

• Replication-dependent histone transcripts possess a conserved stem-loop structure at their 3' terminus, unlike most eukaryotic mRNAs ending in a poly(A) tail.
• The 3' end of histone mRNA is a critical factor influencing its rapid degradation rate.
• Understanding the mechanisms governing histone mRNA stability is crucial for regulating gene expression during the cell cycle.

Purpose of the Study:

• To identify and characterize cytoplasmic protein complexes that bind to the 3' terminal sequences of histone mRNAs.
• To investigate the sequence specificity and evolutionary conservation of these interactions.
• To explore the potential role of these protein complexes in the turnover of histone transcripts.

Main Methods:

• Biochemical assays to detect and characterize protein-RNA interactions.
• Analysis of sequence-specific binding to 3' terminal sequences of mouse histone H4 and human histone H2A mRNA.
• Investigation of protein complex localization within the cell, including association with polysomes.
• Comparative analysis of binding activities across different species.

Main Results:

• Identification of two distinct cytoplasmic protein complexes that bind specifically to the 3' end of histone H4 and H2A mRNAs.
• Demonstration that these sequence-specific binding activities are conserved from amphibians to humans.
• Evidence suggesting that at least a portion of one protein complex is associated with polysomes, indicating a role in active translation or mRNA processing.

Conclusions:

• Cytoplasmic protein complexes specifically recognize and bind to the 3' terminus of histone mRNAs.
• These interactions are evolutionarily conserved, highlighting their functional importance.
• The association of these complexes with polysomes suggests a potential role in the regulated turnover and expression of histone genes.