Arati Ramesh

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Copper is an essential element that becomes highly cytotoxic when concentrations exceed the capacity of cells to sequester the ion. Here, we identify a new copper-specific repressor (CsoR) of a copper-sensitive operon (cso) in Mycobacterium tuberculosis (Mtb) that is representative of a large, previously uncharacterized family of proteins (DUF156).(More)
All living organisms require mechanisms for coordination of intracellular metal concentrations. Many types of metal-sensing regulatory proteins have been described previously. Data in recent years have revealed that posttranscriptional mechanisms are also utilized for control of metal ion homeostasis in bacteria. In particular, two classes of RNA structural(More)
Bacteria regularly encounter widely varying metal concentrations in their surrounding environment. As metals become depleted or, conversely, accrue to toxicity, microbes will activate cellular responses that act to maintain metal homeostasis. A suite of metal-sensing regulatory ("metalloregulatory") proteins orchestrate these responses by allosterically(More)
The M-box riboswitch couples intracellular magnesium levels to expression of bacterial metal transport genes. Structural analyses on other riboswitch RNA classes, which typically respond to a small organic metabolite, have revealed that ligand recognition occurs through a combination of base-stacking, electrostatic, and hydrogen-bonding interactions. In(More)
Ro ribonucleoproteins are a class of antigenic ribonucleoproteins associated with rheumatic autoimmune diseases like systemic lupus erythematosus and Sjögrens syndrome in humans. Ro ribonucleoproteins are mostly composed of the 60-kDa Ro protein and small cytoplasmic RNAs, called Y RNAs, of unknown function. In eukaryotes, where Ro has been found to(More)
ANTAR proteins are widespread bacterial regulatory proteins that have RNA-binding output domains and utilize antitermination to control gene expression at the post-initiation level. An ANTAR protein, EutV, regulates the ethanolamine-utilization genes (eut) in Enterococcus faecalis. Using this system, we present genetic and biochemical evidence of a general(More)
Riboswitches are regulatory RNAs that control downstream gene expression in response to direct association with intracellular metabolites or metals. Typically, riboswitch aptamer domains bind to a single small-molecule metabolite. In contrast, an X-ray crystallographic structural model for the M-box riboswitch aptamer revealed the absence of an organic(More)
Ethanolamine, a product of the breakdown of phosphatidylethanolamine from cell membranes, is abundant in the human intestinal tract and in processed foods. Effective utilization of ethanolamine as a carbon and nitrogen source may provide a survival advantage to bacteria that inhabit the gastrointestinal tract and may influence the virulence of pathogens. In(More)
The ethanolamine utilization (eut) locus of Enterococcus faecalis, containing at least 19 genes distributed over four polycistronic messenger RNAs, appears to be regulated by a single adenosyl cobalamine (AdoCbl)-responsive riboswitch. We report that the AdoCbl-binding riboswitch is part of a small, trans-acting RNA, EutX, which additionally contains a(More)
Catalysis in the biological context was largely thought to be a protein-based phenomenon until the discovery of RNA catalysts called ribozymes. These discoveries demonstrated that many RNA molecules exhibit remarkable structural and functional versatility. By virtue of these features, naturally occurring ribozymes have been found to be involved in(More)