In molecular biology, the PyrD leader is a cis-regulatory RNA element found at the 5' of the PyrC mRNA in Pseudomonadota. The PyrD gene encodes dihydroorotate dehydrogenase, an enzyme involved in pyrimidine biosynthesis. The PyrD leader regulates expression of PyrD. Translation initiation can occur at more than one different site within this leader sequence, under high cytidine triphosphate or guanosine triphosphate conditions the translation initiation site is upstream of that used under low CTP/GTP conditions, additional cytosine residues are incorporated into the mRNA resulting in the formation of an RNA hairpin. This hairpin blocks ribosome-binding at the Shine-Dalgarno sequence, and therefore blocks expression of PyrD. Under low CTP/GTP conditions the initiation site is further downstream and does not result in hairpin formation, so the ribosome can bind to the Shine-Dalgarno sequence and PyrD is expressed.
Further reading
- Vial, TC; Baker, KE; Kelln, RA (Aug 1, 1993). "Dual control by purines and pyrimidines of the expression of the pyrD gene of Salmonella typhimurium". FEMS Microbiology Letters. 111 (2–3): 309–314. doi:10.1016/0378-1097(93)90398-l. PMID 8104841.
- Frick, MM; Neuhard, J; Kelln, RA (Dec 12, 1990). "Cloning, nucleotide sequence and regulation of the Salmonella typhimurium pyrD gene encoding dihydroorotate dehydrogenase". European Journal of Biochemistry. 194 (2): 573–578. doi:10.1111/j.1432-1033.1990.tb15654.x. PMID 2269282.
- Jensen, KF (Apr 1989). "Regulation of Salmonella typhimurium pyr gene expression: effect of changing both purine and pyrimidine nucleotide pools". Journal of General Microbiology. 135 (4): 805–815. doi:10.1099/00221287-135-4-805. PMID 2689594.
References
- Björnberg, O; Grüner, AC; Roepstorff, P; Jensen, KF (Mar 9, 1999). "The activity of Escherichia coli dihydroorotate dehydrogenase is dependent on a conserved loop identified by sequence homology, mutagenesis, and limited proteolysis". Biochemistry. 38 (10): 2899–2908. doi:10.1021/bi982352c. PMID 10074342.
- Sørensen, KI (Feb 25, 1994). "Conformational heterogeneity in the Salmonella typhimurium pyrC and pyrD leader mRNAs produced in vivo". Nucleic Acids Research. 22 (4): 625–631. doi:10.1093/nar/22.4.625. PMC 307853. PMID 7510398.
- Turnbough CL, Switzer RL (2008). "Regulation of pyrimidine biosynthetic gene expression in bacteria: repression without repressors". Microbiol Mol Biol Rev. 72 (2): 266–300, table of contents. doi:10.1128/MMBR.00001-08. PMC 2415746. PMID 18535147.