Role of SMU Homologues in Pre-mRNA Splicing During Maize and Arabidopsis Development

A maize (Zea mays ssp. mays) opaque mutant, mto38 (Mutator-taggedopaque 38), was shown to cosegregate with a Mutator-tagged genomicfragment. Sequence analysis of the DNA indicated that it contained a genesimilar to the smu-2 (suppressor of mec-8 unc-52) gene in nematodes. Previous studies showed that the mutations in either thenematode smu-1 or smu-2 genes affect splicing of the unc-52 pre-mRNA, and SMU-1 protein interacts with SMU-2 protein. In addition, human homologues of SMU-1 and SMU-2 proteins wereidentified from human spliceosome. Thus, animal SMU-1 and SMU-2 homologuesappear to play a role in pre-mRNA splicing. Plant SMU-1 and SMU-2 homologueshave not been characterized. This study demonstrated that a Mutator insertion in Zmsmu2 (Zea mays homologue of nematode smu-2) geneis responsible for multiple mutant phenotypes. Transcript profiling of mto38/zmsmu2-1endosperm revealed that defective rRNA processing and inefficient proteinsynthesis in the mutant can explain the mutant endosperm phenotypes.Furthermore, splicing of multiple pre-mRNAs is altered in zmsmu2-1endosperm, indicating a regulatory role for ZmSMU2 in pre-mRNA splicing. Thisstudy also describes the AtSMU1 and AtSMU2 genes, which encodethe Arabidopsis homologues of nematode SMU-1 and SMU-2, respectively.The SMU-2 homologues of Arabidopsis and maize physically interact with their corresponding SMU-1 homologues. Genetic analysis indicated that the AtSMU1 and AtSMU2 genes are in the same genetic pathway, and mutations in AtSMU1 and AtSMU2 also result in altered splicing of pre-mRNAs, as was true for zmsmu2. Taken together, the data presented in this study indicate a rolefor plant SMU-2 homologues in pre-mRNA splicing.

Name thesis:degree_name

PhD

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Plant Science

Grantor dc:publisher

The University of Arizona.

Year dc:date.issued

2006

Author dc:creator

• Chung, Taijoon

Committee members dc:contributor.committeemember

• Larkins, Brian A.
• Chandler, Vicky L.
• Leonard, Robert T.
• Vierling, Elizabeth
• Yadegari, Ramin

Statement dc:rights

• Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.

Language dc:language.iso

EN

Handle dc:identifier.uri

http://hdl.handle.net/10150/195508

OAI identifier oai:identifier

oai:repository.arizona.edu:10150/195508