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Intrinsic Structural Disorder Observed in the Cell Cycle Regulatory GTPase Nucleostemin
Author(s) -
Daman Tyler,
Robinson Victoria
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.712.4
Subject(s) - biogenesis , nucleolus , biology , microbiology and biotechnology , ribosome biogenesis , computational biology , gtpase , intrinsically disordered proteins , ran , circular dichroism , biophysics , ribosome , rna , genetics , biochemistry , nucleus , gene
To maintain tissue homeostasis, it is necessary to control cell proliferation based on nutrient availability and environmental factors. Numerous lines of evidence suggest that the balance of the cellular concentrations of nucleostemin (NS), a non‐canonical circularly permuted GTPase, is critical for cell cycle progression. It does so by interacting with different partners involved in a wide range of cellular processes such as ribosome biogenesis, tumor suppression, and DNA maintenance. The cellular function of NS is regulated by guanine nucleotide driven localization to the nucleolus. Currently, little is known about the structure of NS and how it is modulated during this event. Using an ensemble of biophysical techniques, we present the first structural characterization of Drosophila melanogaster Nucleostemin (dNS1), which is 33% identical and 67% similar to the human homolog. This represents the first structural data collected for a eukaryotic cpGTPase. Bioinformatic analysis, limited proteolysis, and circular dichroism were used in combination to determine that dNS1 contains large intrinsically disordered regions, primarily at the N‐ and C‐ termini. Small‐angle X‐ray scattering (SAXS) experiments, supported by analytical ultracentrifugation, provided a solution description of dNS1. Data obtained from these techniques establish that dNS1 exists as a highly elongated monomer, and confirms the lack of secondary structure. In summary, our studies show that NS contains large regions of structural disorder, which likely facilitates its broad partner recognition.