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33 results on '"Sudarsan, Narasimhan"'

6. Architectures and complex functions of tandem riboswitches

Author

Sherlock, Madeline E., primary, Higgs, Gadareth, additional, Yu, Diane, additional, Widner, Danielle L., additional, White, Neil A., additional, Sudarsan, Narasimhan, additional, Sadeeshkumar, Harini, additional, Perkins, Kevin R., additional, Mirihana Arachchilage, Gayan, additional, Malkowski, Sarah N., additional, King, Christopher G., additional, Harris, Kimberly A., additional, Gaffield, Glenn, additional, Atilho, Ruben M., additional, and Breaker, Ronald R., additional

Published
2022
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13. Na+riboswitches regulate genes for diverse physiological processes in bacteria

Author

White, Neil, Sadeeshkumar, Harini, Sun, Anna, Sudarsan, Narasimhan, and Breaker, Ronald R.

Abstract

Organisms presumably have mechanisms to monitor and physiologically adapt to changes in cellular Na+concentrations. Only a single bacterial protein has previously been demonstrated to selectively sense Na+and regulate gene expression. Here we report a riboswitch class, previously called the ‘DUF1646 motif’, whose members selectively sense Na+and regulate the expression of genes relevant to sodium biology. Many proteins encoded by Na+-riboswitch-regulated genes are annotated as metal ion transporters, whereas others are involved in mitigating osmotic stress or harnessing Na+gradients for ATP production. Na+riboswitches exhibit dissociation constants in the low mM range, and strongly reject all other alkali and alkaline earth ions. Likewise, only Na+triggers riboswitch-mediated transcription and gene expression changes. These findings reveal that some bacteria use Na+riboswitches to monitor, adjust and exploit Na+concentrations and gradients, and in some instances collaborate with c-di-AMP riboswitches to coordinate gene expression during osmotic stress.

Published
2022
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16. An mRNA structure in bacteria that controls gene expression by binding lysine

Author

Sudarsan, Narasimhan, Wickiser, J. Kenneth, Nakamura, Shingo, Ebert, Margaret S., and Breaker, Ronald R.

Subjects
Lysine -- Genetic aspects, Bacillus subtilis -- Genetic aspects, Genetic transcription -- Physiological aspects, RNA -- Genetic aspects, Genetic research -- Analysis, Biological sciences
Abstract

Research has been conducted on Bacillus subtilis gene. The authors have demonstrated that this gene carries a conserved RNA element which is a lysine-responsive riboswitch.

Published
2003

17. rexB of bacteriophage λ is an anti-cell death gene

Author

Hanna Engelberg-Kulka, Gad Glaser, Sudarsan Narasimhan, Myriam Reches, Rachel Schoulaker-Schwarz, Yoel Klemes, and Einat Aizenman

Subjects
Genotype, Operon, Guanosine, Addiction module, Biology, medicine.disease_cause, Ligases, Bacteriophage, Viral Proteins, chemistry.chemical_compound, Plasmid, Lysogenic cycle, Escherichia coli, medicine, Cloning, Molecular, Lysogeny, Prophage, Adenosine Triphosphatases, Guanylyl Imidodiphosphate, Multidisciplinary, Serine Endopeptidases, Endopeptidase Clp, Biological Sciences, biology.organism_classification, Bacteriophage lambda, Recombinant Proteins, Mutagenesis, Insertional, chemistry, Biochemistry, bacteria, Plasmids
Abstract

In Escherichia coli , programmed cell death is mediated through “addiction modules” consisting of two genes; the product of one gene is long-lived and toxic, whereas the product of the other is short-lived and antagonizes the toxic effect. Here we show that the product of λ rexB , one of the few genes expressed in the lysogenic state of bacteriophage λ, prevents cell death directed by each of two addiction modules, phd-doc of plasmid prophage P1 and the rel mazEF of E. coli , which is induced by the signal molecule guanosine 3′,5′-bispyrophosphate (ppGpp) and thus by amino acid starvation. λRexB inhibits the degradation of the antitoxic labile components Phd and MazE of these systems, which are substrates of ClpP proteases. We present a model for this anti-cell death effect of λRexB through its action on the ClpP proteolytic subunit. We also propose that the λ rex operon has an additional function to the well known phenomenon of exclusion of other phages; it can prevent the death of lysogenized cells under conditions of nutrient starvation. Thus, the rex operon may be considered as the “survival operon” of phage λ.

Published
1998

32. Antibacterial lysine analogs that target lysine riboswitches.

Author

Blount, Kenneth F., Joy Xin Wang, Jinsoo Lim, Sudarsan, Narasimhan, and Breaker, Ronald R.

Subjects
AMINO acids, RNA, NUCLEIC acids, MESSENGER RNA, ORGANIC synthesis, BIOCHEMICAL engineering, BIOCHEMISTRY, LYSINE
Abstract

Lysine riboswitches are bacterial RNA structures that sense the concentration of lysine and regulate the expression of lysine biosynthesis and transport genes. Members of this riboswitch class are found in the 5′ untranslated region of messenger RNAs, where they form highly selective receptors for lysine. Lysine binding to the receptor stabilizes an mRNA tertiary structure that, in most cases, causes transcription termination before the adjacent open reading frame can be expressed. A lysine riboswitch conceivably could be targeted for antibacterial therapy by designing new compounds that bind the riboswitch and suppress lysine biosynthesis and transport genes. As a test of this strategy, we have identified several lysine analogs that bind to riboswitches in vitro and inhibit Bacillus subtilis growth, probably through a mechanism of riboswitch-mediated repression of lysine biosynthesis. These results indicate that riboswitches could serve as new classes of antibacterial drug targets. [ABSTRACT FROM AUTHOR]

Published
2007
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33. An mRNA structure that controls gene expression by binding S-adenosylmethionine.

Author

Winkler, Wade C, Nahvi, Ali, Sudarsan, Narasimhan, Barrick, Jeffrey E, and Breaker, Ronald R

Subjects
MESSENGER RNA, ADENOSYLMETHIONINE, GENE expression, BIOSYNTHESIS, BACILLUS subtilis, GENETIC regulation
Abstract

Riboswitches are metabolite-binding RNA structures that serve as genetic control elements for certain messenger RNAs. These RNA switches have been identified in all three kingdoms of life and are typically responsible for the control of genes whose protein products are involved in the biosynthesis, transport or utilization of the target metabolite. Herein, we report that a highly conserved RNA domain found in bacteria serves as a riboswitch that responds to the coenzyme S-adenosylmethionine (SAM) with remarkably high affinity and specificity. SAM riboswitches undergo structural reorganization upon introduction of SAM, and these allosteric changes regulate the expression of 26 genes in Bacillus subtilis. This and related findings indicate that direct interaction between small metabolites and allosteric mRNAs is an important and widespread form of genetic regulation in bacteria. [ABSTRACT FROM AUTHOR]

Published
2003
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