Apparent dissociation constant of thiM riboswitch and its effector thiamine triphosphate (TPP)

Value 600 nM
Organism Bacteria Escherichia coli
Reference Winkler W, Nahvi A, Breaker RR. Thiamine derivatives bind messenger RNAs directly to regulate bacterial gene expression. Nature. 2002 Oct 31 419(6910):952-6.PubMed ID12410317
Method Researchers prepared ß-galactosidase translational fusion constructs that encompass the 5'-untranslated regions of thiM and thiC mRNAs of E. coli, each of which includes a previously identified ‘thi box’ domain. The sensitivity of metabolite detection by these mRNAs was assessed by establishing apparent dissociation constant (apparent KD) values for TPP, thiamine, and thiamine monophosphate (TP). Values were generated by monitoring the extent of spontaneous cleavage at several ligand-sensitive sites within the RNA over a range of ligand concentrations.
Comments Probing of a trace amount of 165 thiM RNA (165 refers to number of nucleotides in RNA) with TPP concentrations ranging from zero to 100?µM (or up to 10?mM with certain analogues) reveals that half-maximal modulation of RNA structure occurs when approximately 600?nM TPP is present (Fig. 2a), which reflects an apparent KD of 600?nM. See BNID 105441
Entered by Uri M
ID 105442