PyrG leader

In molecular biology, the PyrG leader is a cis-regulatory RNA element found at the 5' of the PyrG mRNA. The PyrG gene encodes a CTP synthase, which is involved in pyrimidine biosynthesis. The PyrG leader regulates expression of PyrG, PyrG can form into two different hairpin structures, a terminator or an anti-terminator. Under low CTP conditions, guanine (G) residues are incorporated at a specific site within the PyrG leader, these allow base-pairing with a uracil (U)-rich region and the formation of an anti-terminator loop, this results in increased expression of PyrG. Under high CTP conditions the guanines are not added, the anti-terminator loop cannot form and instead a terminator loop is formed, preventing further PyrG expression.

Further reading

• Meng Q, Turnbough CL, Switzer RL (2004). "Attenuation control of pyrG expression in Bacillus subtilis is mediated by CTP-sensitive reiterative transcription". Proc Natl Acad Sci U S A. 101 (30): 10943–10948. doi:10.1073/pnas.0403755101. PMC 503723. PMID 15252202.
• Meng Q, Switzer RL (2002). "cis-acting sequences of Bacillus subtilis pyrG mRNA essential for regulation by antitermination". J Bacteriol. 184 (23): 6734–6738. doi:10.1128/jb.184.23.6734-6738.2002. PMC 135426. PMID 12426364.
• Jørgensen CM, Hammer K, Martinussen J (2003). "CTP limitation increases expression of CTP synthase in Lactococcus lactis". J Bacteriol. 185 (22): 6562–6574. doi:10.1128/jb.185.22.6562-6574.2003. PMC 262100. PMID 14594829.