Diverse functions of RNA-binding proteins in the biogenesis of ribonucleoprotein particles / Jeongsik Yong.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Yong, Jeongsik.

Contributor:

Dreyfuss, Gideon, advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Biochemistry and molecular biophysics.

Biochemistry and molecular biophysics--Penn dissertations.

Biochemistry and Molecular Biophysics.

Academic Dissertations as Topic.

Medical Subjects:

Biochemistry and Molecular Biophysics.

Academic Dissertations as Topic.

Local Subjects:

Penn dissertations--Biochemistry and molecular biophysics.

Biochemistry and molecular biophysics--Penn dissertations.

Physical Description:

viii, 202 pages : illustrations (some color) ; 29 cm

Production:

2002.

Summary:

RNA-binding proteins play crucial roles in the biogenesis of RNPs. In eukaryotes, mature mRNAs are produced by pre-mRNA processing in the cell nucleus. Along this pathway, heterogeneous nuclear ribonucleoprotein (hnRNP) complexes are formed due to association of numerous RNA-binding proteins with these transcripts. Here, I investigated the dynamic change of protein composition in the hnRNP complexes during pre-mRNA processing and demonstrated that pre-mRNA splicing creates novel mRNP complexes distinct from hnRNP complexes. One of the components of mRNP complex, Y14, associates preferentially with spliced mRNAs but not with pre-mRNAs, introns, or mRNAs produced from intronless cDNAs. Y14 binds to both nuclear mRNAs and newly exported cytoplasmic mRNAs. Microinjections of pre-mRNAs into Xenopus oocytes followed by immunoprecipitations of RNase fragmented mRNAs showed that Y14 associates upstream of exon-exon junctions. These findings demonstrate that the splicing-dependent binding of Y14 provides a position-specific molecular memory that communicates to the cytoplasm the location of exon-intron boundaries and further suggest that pre-mRNA splicing serves not only to remove introns but also to imprint a unique mRNP. Splicing of pre-mRNA takes place in the spliceosome, a dynamic assembly of pre-mRNA, small nuclear RNPs (snRNPs), and numerous protein factors. The biogenesis of spliceosomal U snRNPs, the catalytic core of the spliceosome, is a complex process. Important and unexpected insights into this process of snRNP assembly emerged from studies on the function of the SMN complex. Spliceosomal snRNPs have a common core comprised of seven Sm proteins and each snRNA. To mediate the assembly of snRNPs, the SMN complex must have the capacity to bring together both the Sm proteins and the U snRNAs. Here, I describe that the SMN complex interacts directly with the spliceosomal U snRNAs. In U1 snRNA, the stem-loop 1 domain (SL1) is necessary and sufficient for SMN complex binding. Substitution of three nucleotides in the loop of SL1 (SL1A3) abolishes SMN interaction, and the corresponding U1 snRNA is impaired in U1 snRNP biogenesis. In addition, an excess of SL1 but not SL1A3 interferes the binding of the SMN complex with the U snRNAs and therefore inhibits the snRNPs assembly. These findings demonstrate that the interaction of the SMN complex with the U snRNAs is crucial for U snRNPs biogenesis further supporting the direct role of the SMN complex in RNP biogenesis.

Notes:

Supervisor: Gideon Dreyfuss.

Thesis (Ph.D. in Biochemistry and Molecular Biophysics) -- University of Pennsylvania, 2002.

Includes bibliographical references.

Local Notes:

University Microfilms order no.: 3055018.

OCLC:

244972085