Nitrogen cost minimization is promoted by structural changes in the transcriptome of N-deprived Prochlorococcuscells

Autor: Read, Robert W, Berube, Paul M, Biller, Steven J, Neveux, Iva, Cubillos-Ruiz, Andres, Chisholm, Sallie W, Grzymski, Joseph J
Zdroj: The ISME Journal; October 2017, Vol. 11 Issue: 10 p2267-2278, 12p
Abstrakt: Prochlorococcusis a globally abundant marine cyanobacterium with many adaptations that reduce cellular nutrient requirements, facilitating growth in its nutrient-poor environment. One such genomic adaptation is the preferential utilization of amino acids containing fewer N-atoms, which minimizes cellular nitrogen requirements. We predicted that transcriptional regulation might further reduce cellular N budgets during transient N limitation. To explore this, we compared transcription start sites (TSSs) in ProchlorococcusMED4 under N-deprived and N-replete conditions. Of 64 genes with primary and internal TSSs in both conditions, N-deprived cells initiated transcription downstream of primary TSSs more frequently than N-replete cells. Additionally, 117 genes with only an internal TSS demonstrated increased internal transcription under N-deprivation. These shortened transcripts encode predicted proteins with an average of 21% less N content compared to full-length transcripts. We hypothesized that low translation rates, which afford greater control over protein abundances, would be beneficial to relatively slow-growing organisms like Prochlorococcus. Consistent with this idea, we found that Prochlorococcusexhibits greater usage of glycine–glycine motifs, which causes translational pausing, when compared to faster growing microbes. Our findings indicate that structural changes occur within the ProchlorococcusMED4 transcriptome during N-deprivation, potentially altering the size and structure of proteins expressed under nutrient limitation.
Databáze: Supplemental Index
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