Increasing the number of ribosomal uL6 mRNA copies accelerates aging of the budding yeast

BACKGROUND: Aging is a biological process from which there is no escape. Diverse factors contribute to aging, most notably cell energy metabolism. Ribosome biogenesis and translation are the two main energy-consuming processes that contribute to longevity. It has repeatedly been shown that translation disorders caused by deletion of ribosomal genes delay aging. However, the effect of increasing the amount of ribosomal proteins has remained elusive. METHODS AND RESULTS: We determine the relative level of the uL6A and uL6B mRNA derived from the genome and the plasmid. The appearance of additional copies of plasmid-derived uL6 leads to an increase in uL6A and uL6B derived from the BY4741 genome (mainly form B). The relative amount of mRNA of plasmid form B is several times greater than the amount of mRNA in plasmid form A. The level of mRNA derived from the plasmid is increased many times compared to the mRNA of genomic origin. Additionally, the study indicates that excess of uL6A is a limiting or even harmful factor in the reaction to stressful conditions. Therefore, our hypothesis states that uL6A transcription or mRNA uL6A degradation in yeast cells are tightly regulated. our data clearly demonstrate that aging is accelerated when additional copies of uL6 paralogs appear. CONCLUSION: Overexpression of both uL6A or uL6B accelerates aging in the budding yeast. The level of uL6A mRNA is tightly controlled by yeast cell. The uL6a protein plays a pivotal role in the response to environmental stress, including oxidative and osmotic stress, and thus may fall into the class of moonlighting ribosomal proteins with extra-ribosomal function.