Olesya O. Panasenko

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The Ccr4-Not complex is a unique, essential and conserved multi-subunit complex that acts at the level of many different cellular functions to regulate gene expression. Two enzymatic activities, namely ubiquitination and deadenylation, are provided by different subunits of the complex. However, studies over the last decade have demonstrated a tantalizing(More)
In this study we determine that the Not4 E3 ligase is important for proteasome integrity. Consequently, deletion of Not4 leads to an accumulation of polyubiquitinated proteins and reduced levels of free ubiquitin. In the absence of Not4, the proteasome regulatory particle (RP) and core particle (CP) form salt-resistant complexes, and all other forms of RPs(More)
In this study, we determine that Saccharomyces cerevisiae Not4 E3 ligase ubiquitinates Rps7A in vivo and in vitro, but not its paralogue, Rps7B. Ubiquitinated Rps7A is detectable only in 80S and polysomes, but not in free 40S fractions. A different role of the Rps7 paralogues in vivo is supported by the observation that the deletion of Rps7A but not Rps7B(More)
In this work we used micro-array experiments to determine the role of each nonessential subunit of the conserved Ccr4-Not complex in the control of gene expression in the yeast Saccharomyces cerevisiae. The study was performed with cells growing exponentially in high glucose and with cells grown to glucose depletion. Specific patterns of gene deregulation(More)
BACKGROUND Ccr4-Not is a highly conserved multi-protein complex consisting in yeast of 9 subunits, including Not5 and the major yeast deadenylase Ccr4. It has been connected functionally in the nucleus to transcription by RNA polymerase II and in the cytoplasm to mRNA degradation. However, there has been no evidence so far that this complex is important for(More)
In this work, we determine that the Saccharomyces cerevisiae Ccr4-Not complex controls ubiquitination of the conserved ribosome-associated heterodimeric EGD (enhancer of Gal4p DNA binding) complex, which consists of the Egd1p and Egd2p subunits in yeast and is named NAC (nascent polypeptide-associated complex) in mammals. We show that the EGD complex(More)
In this work we addressed the role of ubiquitination in the function of the nascent polypeptide-associated complex (NAC), named EGD in the yeast Saccharomyces cerevisiae. To this end, we first identified the lysines residues required for ubiquitination of EGD/NAC. While simultaneous mutation of many lysines in the alpha-subunit of NAC (Egd2p) was required(More)
The Ccr4-Not complex is a conserved multi-subunit complex in eukaryotes that carries 2 enzymatic activities: ubiquitination mediated by the Not4 RING E3 ligase and deadenylation mediated by the Ccr4 and Caf1 orthologs. This complex has been implicated in all aspects of the mRNA life cycle, from synthesis of mRNAs in the nucleus to their degradation in the(More)
Recent studies have suggested that a sub-complex of RNA polymerase II composed of Rpb4 and Rpb7 couples the nuclear and cytoplasmic stages of gene expression by associating with newly made mRNAs in the nucleus, and contributing to their translation and degradation in the cytoplasm. Here we show by yeast two hybrid and co-immunoprecipitation experiments,(More)
The current understanding of gene expression considers transcription and translation to be independent processes. Challenging this notion, we found that translation efficiency is determined during transcription elongation through the imprinting of mRNAs with Not1, the central scaffold of the Ccr4-Not complex. We determined that another subunit of the(More)