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Proc Natl Acad Sci U S A. 2014 Jul 22;111(29):E2937-46. doi: 10.1073/pnas.1406381111. Epub 2014 Jul 7.

Molecular mechanisms for the regulation of histone mRNA stem-loop-binding protein by phosphorylation.

Author information

1
Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709;
2
Department of Biological Sciences, Columbia University, New York, NY 10027;
3
Department of Biochemistry and Biophysics andIntegrative Program in Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599.
4
Department of Biochemistry and Biophysics andIntegrative Program in Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599 marzluff@med.unc.edu ltong@columbia.edu hall4@niehs.nih.gov.
5
Department of Biological Sciences, Columbia University, New York, NY 10027; marzluff@med.unc.edu ltong@columbia.edu hall4@niehs.nih.gov.
6
Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709; marzluff@med.unc.edu ltong@columbia.edu hall4@niehs.nih.gov.

Abstract

Replication-dependent histone mRNAs end with a conserved stem loop that is recognized by stem-loop-binding protein (SLBP). The minimal RNA-processing domain of SLBP is phosphorylated at an internal threonine, and Drosophila SLBP (dSLBP) also is phosphorylated at four serines in its 18-aa C-terminal tail. We show that phosphorylation of dSLBP increases RNA-binding affinity dramatically, and we use structural and biophysical analyses of dSLBP and a crystal structure of human SLBP phosphorylated on the internal threonine to understand the striking improvement in RNA binding. Together these results suggest that, although the C-terminal tail of dSLBP does not contact the RNA, phosphorylation of the tail promotes SLBP conformations competent for RNA binding and thereby appears to reduce the entropic penalty for the association. Increased negative charge in this C-terminal tail balances positively charged residues, allowing a more compact ensemble of structures in the absence of RNA.

KEYWORDS:

NMR; X-ray crystallography; intrinsically disordered protein

PMID:
25002523
PMCID:
PMC4115514
DOI:
10.1073/pnas.1406381111
[Indexed for MEDLINE]
Free PMC Article

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