Project description:In this study, we characterized the homeostasis of the marine cyanobacteria Synechococcus sp. PCC7002 (BMB04) growing in chemically characterized synthetic seawater with three different levels of iron limitation representative of the modern ocean. Using transcriptomic approach, we identified the sequence of physiological responses to increasing Fe limitation. Our results showed an increase in the number of dysregulated genes and in the complexity of the response to increasing Fe limitation. Genes involved in photosynthesis were strongly down-regulated under MiFeL, while membrane transporters were up-regulated. Genes involved in regulation of energy metabolism responded under strong Fe limitation, while fine metabolic regulation of co-factors expression and activation of specific cellular mechanisms to minimize oxidative stress were only observed under severe Fe limitation. Additionally, our results demonstrate the limitations in the construct of the bioreporter BMB04 that hamper its application in areas of the ocean strongly Fe limited.
Project description:RNase III is a ribonucleases that recognizes and cleaves double-stranded RNA. RNase III has been known be involved in rRNA processing, but has many additional roles controlling both expression and RNA turnover of specific messages. Many organisms have just one RNase III while some have both a full length RNase III and a mini-III that lacks the double-stranded RNA binding domain. The cyanobacteria Synechococcus sp. PCC 7002 has three homologs of RNase III that are unessential even when deleted in combination. We were interested what coding regions these RNase III enzymes were influencing and if they had redundant or distinct specificities. To address these questions we collected samples for RNA-sequencing from WT, the single, double, and triple RNase III mutants in triplicate. Approximately 20% of genes were differentially expressed in various mutants with some operons and regulons showing complex changes in expression levels between mutants. We describe the role of two RNase III’s in 23S rRNA maturation, and show how the third is involved in copy number regulation of one of the six plasmids (pAQ3). Purified enzymes were capable of cleaving some E. coli RNase III target sequences, highlighting the remarkably conserved substrate specificity between organisms yet complex regulation of gene expression.
Project description:RNA samples from cells collected at twenty four time points in 48-hours diurnal cycles were analyzed, and they compared between each other for transcriptional profiles of global genes
Project description:We employed chromatin pull-down and deep sequencing to globally identify HetR DNA targets in vivo at 6 hours after fixed-nitrogen deprivation. We identified novel DNA binding targets of tagged HetR-6xHis and defined a consensus HetR binding site from these HetR target sequences. Chromatin pull down of hetR mutant strain UHM103 carrying pAM4375, which expresses HetR-6xHis, and a wild-type control. One dataset was collected.
