期刊
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
卷 1867, 期 8, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.bbamcr.2020.118727
关键词
Ppz1; Protein phosphatase; Ribosomal proteins; Translation initiation; Yeast
资金
- AEI/FEDER, EU [BFU2017-82574-P, BFU2016-75352-P]
- Ministerio de Industria, Economia y Competitividad, Spain
- ERDF
- Ministerio de Economia y Competitividad (Spain)
- China Scholarship Council
- UAB
The Ser/Thr protein phosphatase Ppz1 from Saccharomyces cerevisiae is the best characterized member of a family of enzymes only found in fungi. Ppz1 is regulated in vivo by two inhibitory subunits, Hal3 and Vhs3, which are moonlighting proteins also involved in the decarboxylation of the 4-phosphopantothenoylcysteine (PPC) intermediate required for coenzyme A biosynthesis. It has been reported that, when overexpressed, Ppz1 is the most toxic protein in yeast. However, the reasons for such toxicity have not been elucidated. Here we show that the detrimental effect of excessive Ppz1 expression is due to an increase in its phosphatase activity and not to a plausible down-titration of the PPC decarboxylase components. We have identified several genes encoding ribosomal proteins and ribosome assembly factors as mild high-copy suppressors of the toxic Ppz1 effect. Ppz1 binds to ribosomes engaged in translation and copurifies with diverse ribosomal proteins and translation factors. Ppz1 overexpression results in Gcn2-dependent increased phosphorylation of eIF2a at Ser-51. Consistently, deletion of GCN2 partially suppresses the growth defect of a Ppz1 overexpressing strain. We propose that the deleterious effects of Ppz1 overexpression are in part due to alteration in normal protein synthesis.
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