The Gemin2 complex : an evolving view of SMN mediated snRNP assembly / Eric S. Babiash.

Format:

Book

Manuscript

Thesis/Dissertation

Author/Creator:

Babiash, Eric S., author.

Contributor:

Dreyfuss, Gideon, degree supervisor.

Domínguez, Roberto, degree committee member.

Kolb, Steven J., degree committee member.

Lynch, Kristen W., degree committee member.

Mourelatos, Zissimos, degree committee member.

Skordalakes, Emmanuel, degree committee member.

Wilusz, Jeremy E., degree committee member.

University of Pennsylvania. Department of Biochemistry and Molecular Biophysics, degree granting institution.

Language:

English

Subjects (All):

Penn dissertations--Biochemistry and molecular biophysics.

Biochemistry and molecular biophysics--Penn dissertations.

Local Subjects:

Penn dissertations--Biochemistry and molecular biophysics.

Biochemistry and molecular biophysics--Penn dissertations.

Physical Description:

x, 166 leaves : illustrations ; 29 cm

Production:

[Philadelphia, Pennsylvania] : University of Pennsylvania, 2017.

Summary:

Assembly of spliceosome snRNPs requires a megadalton molecular machine called the survival of motor neuron (SMN) complex. In higher eukaryotes, this complex consists of SMN, Gemins2-8 and unrip. Deficiency in SMN causes spinal muscular atrophy (SMA), a leading cause of heritable mortality in infants and children. The mechanism of precisely how seven Sm proteins are arranged in a ring around an snRNA, to form a snRNP was not well understood, due in part to the large number of components and heterogeneity of the SMN complex. Through use of several techniques including: RNA gel-shifts, pull-downs, Förster resonance energy transfer, ultracentrifugation, electron microscopy, molecular modeling and genetic manipulation in simple model organisms and human cells, this area was illuminated. Here I will present evidence for Sm5 dependent association of Gemin2 with SMN. Through a series of hydrophobic interactions between amino and carboxy termini, binding of Sm protein to Gemin2 opens a binding site for SMN on its distal side, in both human and S. pombe. I will prove that human SMN complexes in cells require Gemin8 to form large oligomers. I will demonstrate that the oligomerization state of S. pombe SMN is a tetramer, and visualize its complete SMN complex. I will show that both S. pombe and S. cerevisiae SMN-Gemin2 and Brr1 are sufficient for snRNP assembly from recombinant sources. I will further show that S. cerevisiae Brr1 is capable of binding all substrates of the SMN complex. Through genetics I demonstrate a toxicity from Gemin2, when its levels exceed SMN capacity in S. pombe. Finally, I will suggest that the imbalance of Gemin2 and SMN occurs in the devastating childhood disease, SMA, and is a contributing factor. These results amount to a paradigm shift wherein Gemin2 usurps SMN as the most important member of the now SMN-Gemin2 complex for snRNP. Furthermore, with toxicity of excess Gemin2 relative to SMN and the likelihood of this occurring in SMA patients, Gemin2's position of importance as a potential therapeutic target in SMA has been revealed.

Notes:

Ph. D. University of Pennsylvania 2017.

Department: Biochemistry and Molecular Biophysics.

Supervisor: Gideon Dreyfuss.

Includes bibliographical references.

OCLC:

1334945622