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Binding constant of riboswitches to TPP, FMN and c-di-GMP

Range	mid picomolar range
Organism	bacteria
Reference	Breaker RR. Riboswitches and the RNA world. Cold Spring Harb Perspect Biol. 2012 Feb 1 4(2). pii: a003566. doi: 10.1101/cshperspect.a003566. p.5 right column top paragraphPubMed ID21106649
Primary Source	[1] Welz R, Breaker RR. 2007. Ligand binding and gene control characteristics of tandem riboswitches in Bacillus anthracis. RNA 13: 573–582. [2] Lee ER, Blount KF, Breaker RR. 2009. Roseoflavin is a natural antibacterial compound that binds to FMN riboswitches and regulates gene expression. RNA Biol 6: 187–194. [3] Sudarsan N, Lee ER, Weinberg Z, Moy RH, Kim JN, Link KH, Breaker RR. 2008. Riboswitches in eubacteria sense the second messenger cyclic di-GMP. Science 321: 411–413. doi: 10.1126/science.1159519.PubMed ID17307816, 19246992, 18635805
Comments	"Riboswitch aptamers can tightly bind their target ligands with values for dissociation constants (KD) ranging from the mid micromolar as measured for GlcN6P binding by glmS ribozymes (Winkler et al. 2004 BNID 110861) to the mid picomolar range as observed for some riboswitch representatives that bind thiamine pyrophosphate (TPP) (primary source [1]), flavin mononucleotide (FMN) (primary source [2]) and Cyclic di-guanosine monophosphate (c-di-GMP) (primary source [3]). For Escherichia coli, the presence of a single molecule per cell corresponds to a concentration in the low nanomolar range. Therefore, picomolar KD values for aptamers are at least two orders of magnitude better than required for a riboswitch to detect compounds as rare as one per cell!"
Entered by	Uri M
ID	110862