Abstract
The CCR4-NOT complex has been shown to have multiple roles in mRNA metabolism, including that of transcriptional elongation, mRNA transport, and nuclear exosome function, but the primary function of CCR4 and CAF1 is in the deadenylation and degradation of cytoplasmic mRNA. As previous genetic analysis supported an interaction between SPT5, known to be involved in transcriptional elongation, and that of CCR4, the physical association of SPT5 with CCR4 was examined. A two-hybrid screen utilizing the deadenylase domain of CCR4 as a bait identified SPT5 as a potential interacting protein. SPT5 at its physiological concentration was shown to immunoprecipitate CCR4 and CAF1, and in vitro purified SPT5 specifically could bind to CAF1 and the deadenylase domain of CCR4. We additionally demonstrated that mutations in SPT5 or an spt4 deletion slowed the rate of mRNA degradation, a phenotype associated with defects in the CCR4 mRNA deadenylase complex. Yet, unlike ccr4 and caf1 deletions, spt5 and spt4 defects displayed little effect on the rate of deadenylation. They also did not affect decapping or 5' - 3' degradation of mRNA. These results suggest that the interactions between SPT5/SPT4 and the CCR4-NOT complex are probably the consequences of effects involving nuclear events and do not involve the primary role of CCR4 in mRNA deadenylation and turnover.
Publication Date
12-30-2011
Journal Title
American Journal of Molecular Biology
Publisher
Scientific Research
Digital Object Identifier (DOI)
10.4236/ajmb.2012.21002
Scientific Contribution Number
2458
Document Type
Article
Recommended Citation
Cui, Y. , Chiang, Y. , Viswanathan, P. , Lee, D. and Denis, C. (2012) SPT5 affects the rate of mRNA degradation and physically interacts with CCR4 but does not control mRNA deadenylation. American Journal of Molecular Biology, 2, 11-20. doi: 10.4236/ajmb.2012.21002.
Comments
This is an article published by Scientific Research in American Journal of Molecular Biology in 2011, available online:https://dx.doi.org/10.4236/ajmb.2012.21002