Cloning, characterization and expression of a cDNA clone encoding rabbit ubiquitin-conjugating enzyme, E2(32k)

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Ubiquitin-conjugating enzymes (E2s) are crucial for protein degradation and cell cycle regulation.
• Human CDC34 is a key E2 enzyme involved in cell cycle progression.
• Understanding E2 enzyme homologs in different species provides insights into conserved biological pathways.

Purpose of the Study:

• To clone and characterize the rabbit E2(32k) cDNA.
• To investigate the functional activity of the expressed rabbit E2(32k) protein.
• To compare the rabbit E2(32k) with its human and yeast counterparts.

Main Methods:

• cDNA library screening and Polymerase Chain Reaction (PCR) for gene cloning.
• Northern blot analysis to examine gene expression in various rabbit tissues.
• Heterologous expression of the rabbit E2(32k) in Escherichia coli (E. coli) and subsequent protein purification.
• In vitro assays to assess the protein's ability to form thiolester bonds with ubiquitin and catalyze ubiquitin conjugation.

Main Results:

• A cDNA clone encoding rabbit E2(32k) was successfully obtained.
• The deduced amino acid sequence showed 81% identity to human CDC34 and 50% homology to yeast CDC34 within the conserved core domain.
• Northern blot analysis revealed three transcripts with varying expression levels across six rabbit tissues.
• The recombinant his-tagged rabbit E2(32k) protein was purified to homogeneity and demonstrated functional activity in forming thiolester bonds with ubiquitin.
• The protein was shown to catalyze the conjugation of ubiquitin to histone H2A and H2B.

Conclusions:

• Rabbit E2(32k) is a functional ubiquitin-conjugating enzyme homologous to human and yeast CDC34.
• The characterization of rabbit E2(32k) provides a valuable model for studying ubiquitin conjugation pathways.
• The differential expression of E2(32k) transcripts suggests tissue-specific roles in rabbits.