Genetic interactions of hypomorphic mutations in the m(7)G cap-binding pocket of yeast nuclear cap binding complex: An essential role for Cbc2 in meiosis via splicing of MER3 pre-mRNA Journal Article
| Authors: | Qiu, Z. R.; Chico, L.; Chang, J.; Shuman, S.; Schwer, B. |
| Article Title: | Genetic interactions of hypomorphic mutations in the m(7)G cap-binding pocket of yeast nuclear cap binding complex: An essential role for Cbc2 in meiosis via splicing of MER3 pre-mRNA |
| Abstract: | Nuclear cap binding protein complex (CBC) is a heterodimer of a small subunit (Cbc2 in yeast) that binds the m 7G cap and a large subunit (Sto1 in yeast) that interacts with karyopherins. In order to probe the role of cap recognition in yeast CBC function, we introduced alanine mutations (Y24A, F91A, D120A, D122A, R129A, and R133A) and N-terminal deletions (NΔ21 and NΔ42) in the cap-binding pocket of Cbc2. These lesions had no effect on vegetative growth, but they ameliorated the cold-sensitivity of tgs1Δ cells that lack trimethylguanosine caps (a phenotype attributed to ectopic association of CBC with the m 7G cap of the normally TMG-capped U1 snRNA), thereby attesting to their impact on cap binding in vivo. Further studies of the Cbc2-Y24A variant revealed synthetic lethality or sickness with null mutations of proteins involved in early steps of spliceosome assembly (Nam8, Mud1, Swt21, Mud2, Ist3, and Brr1) and with otherwise benign mutations of Msl5, the essential branchpoint binding protein. Whereas the effects of weakening CBC-cap interactions are buffered by other actors in the splicing pathway during mitotic growth, the NΔ42 allele causes a severe impediment to yeast sporulation and meiosis. RNA analysis revealed a selective defect in the splicing of MER3 and SAE3 transcripts in cbc2-NΔ42 diploids during attempted sporulation. An intronless MER3 cDNA fully restored sporulation and spore viability in the cbc2-NΔ42 strain, signifying that MER3 splicing is a limiting transaction. These studies reveal a new level of splicing control during meiosis that is governed by nuclear CBC. Copyright © 2012 RNA Society. |
| Keywords: | signal transduction; unclassified drug; gene mutation; gene deletion; nonhuman; phenotype; meiosis; allele; protein; genetic variability; intron; in vivo study; amino terminal sequence; guanosine derivative; gene interaction; yeast; alanine; spliceosome; lethality; rna splicing; diploidy; messenger rna precursor; rna analysis; mud2 protein; cold sensitivity; nam8 protein; sporogenesis; u1 snrnp; small nuclear rna; pre-mrna splicing; nuclear cap binding protein; trimethylguanosine; branchpoint binding protein; cap recognition; brr1 protein; cbc2 protein; ist3 protein; mud1 protein; swf21 protein; vegetative growth |
| Journal Title: | RNA |
| Volume: | 18 |
| Issue: | 11 |
| ISSN: | 1355-8382 |
| Publisher: | Cold Spring Harbor Laboratory Press |
| Date Published: | 2012-11-01 |
| Start Page: | 1996 |
| End Page: | 2011 |
| Language: | English |
| DOI: | 10.1261/rna.033746.112 |
| PROVIDER: | scopus |
| PMCID: | PMC3479390 |
| PUBMED: | 23002122 |
| DOI/URL: | |
| Notes: | --- - "Export Date: 2 November 2012" - "CODEN: RNARF" - "Source: Scopus" |
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