@article {343,
	title = {Function of the C-terminal domain of the DEAD-box protein Mss116p analyzed in vivo and in vitro.},
	journal = {J Mol Biol},
	volume = {375},
	number = {5},
	year = {2008},
	month = {2008 Feb 1},
	pages = {1344-64},
	abstract = {The DEAD-box proteins CYT-19 in Neurospora crassa and Mss116p in Saccharomyces cerevisiae are general RNA chaperones that function in splicing mitochondrial group I and group II introns and in translational activation. Both proteins consist of a conserved ATP-dependent RNA helicase core region linked to N and C-terminal domains, the latter with a basic tail similar to many other DEAD-box proteins. In CYT-19, this basic tail was shown to contribute to non-specific RNA binding that helps tether the core helicase region to structured RNA substrates. Here, multiple sequence alignments and secondary structure predictions indicate that CYT-19 and Mss116p belong to distinct subgroups of DEAD-box proteins, whose C-terminal domains have a defining extended alpha-helical region preceding the basic tail. We find that mutations or C-terminal truncations in the predicted alpha-helical region of Mss116p strongly inhibit RNA-dependent ATPase activity, leading to loss of function in both translational activation and RNA splicing. These findings suggest that the alpha-helical region may stabilize and/or regulate the activity of the RNA helicase core. By contrast, a truncation that removes only the basic tail leaves high RNA-dependent ATPase activity and causes only a modest reduction in translation and RNA splicing efficiency in vivo and in vitro. Biochemical analysis shows that deletion of the basic tail leads to weaker non-specific binding of group I and group II intron RNAs, and surprisingly, also impairs RNA-unwinding at saturating protein concentrations and nucleotide-dependent tight binding of single-stranded RNAs by the RNA helicase core. Together, our results indicate that the two sub-regions of Mss116p{\textquoteright}s C-terminal domain act in different ways to support and modulate activities of the core helicase region, whose RNA-unwinding activity is critical for both the translation and RNA splicing functions.},
	keywords = {Adenosine Triphosphatases, Amino Acid Motifs, Amino Acid Sequence, Amino Acids, Basic, Binding Sites, Computational Biology, Conserved Sequence, Crystallography, X-Ray, DEAD-box RNA Helicases, Drosophila Proteins, Escherichia coli, Evolution, Molecular, Gene Silencing, Genetic Complementation Test, Hydrophobic and Hydrophilic Interactions, In Vitro Techniques, Introns, Isoelectric Point, Kinetics, Mitochondria, Molecular Chaperones, Molecular Sequence Data, Mutation, Missense, Plasmids, Protein Binding, Protein Biosynthesis, Protein Structure, Secondary, Protein Structure, Tertiary, RNA, RNA Splicing, RNA, Catalytic, RNA, Fungal, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid, Temperature},
	issn = {1089-8638},
	doi = {10.1016/j.jmb.2007.11.041},
	author = {Mohr, Georg and Del Campo, Mark and Mohr, Sabine and Yang, Quansheng and Jia, Huijue and Jankowsky, Eckhard and Lambowitz, Alan M}
}
