An archaeal protein with homology to the eukaryotic translation initiation factor 5A shows ribonucleolytic activity.

Abstract

To identify proteins that are involved in RNA degradation and processing in Halobacterium sp. NRC-1, we purified proteins with RNA-degrading activity by classical biochemical techniques. One of these proteins showed strong homology to the eukaryotic initiation factor 5A (eIF-5A) and was accordingly named archaeal initiation factor 5A (aIF-5A). Eukaryotic IF-5A is known to be involved in mRNA turnover and to bind RNA. Hypusination of eIF-5A is required for sequence-specific binding of RNA. This unique post-translational modification is restricted to Eukarya and Archaea. The exact function of eIF-5A in RNA turnover remained obscure. Here we show for the first time that aIF-5A from Halobacterium sp. NRC-1 exhibits RNA cleavage activity, preferentially cleaving adjacent to A nucleotides. Detectable RNA binding could be shown for aIF-5A purified from Halobacterium sp. NRC-1 but not from Escherichia coli, while both proteins possess RNA cleavage activity, indicating that hypusination of aIF-5A is required for RNA binding but not for its RNA cleavage activity. Furthermore, we show that the hypusinated form of eIF-5A also shows RNase activity while the unmodified protein does not. Charged amino acids in the N-terminal domain of aIF-5A as well as in the C-terminal domain, which is highly similar to the cold shock protein A (CspA), an RNA chaperone of E. coli, are important for RNA cleavage activity. Moreover our results reveal that activity of aIF-5A depends on its oligomeric state.

• Authors: Steffen Wagner, Gabriele Klug
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 282 Issue 19 Pg. 13966-76 (May 11 2007) ISSN: 0021-9258 [Print] United States
• PMID: 17369252 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Archaeal Proteins
• Ligands
• Peptide Initiation Factors
• RNA, Archaeal
• RNA, Messenger
• RNA-Binding Proteins
• hypusine
• Ribonucleases
• Lysine

Topics

• Amino Acid Sequence
• Archaeal Proteins (genetics, metabolism)
• Base Sequence
• Cells, Cultured
• Eukaryotic Cells
• Genetic Vectors
• Halobacterium (genetics, growth & development, metabolism)
• Ligands
• Lysine (analogs & derivatives, metabolism)
• Molecular Sequence Data
• Nucleic Acid Conformation
• Peptide Initiation Factors (genetics, metabolism)
• Protein Processing, Post-Translational
• RNA, Archaeal (genetics, metabolism)
• RNA, Messenger (genetics, metabolism)
• RNA-Binding Proteins (genetics, metabolism)
• Ribonucleases (genetics, metabolism)
• Sequence Homology, Nucleic Acid
• Eukaryotic Translation Initiation Factor 5A