Rho factor
| Rho ( Escherichia coli K12) | ||
|---|---|---|
|
Existing structural data: s. UniProt |
||
| Mass / length primary structure | 419 amino acids | |
| Secondary to quaternary structure | Homohexamer | |
| Identifier | ||
| Gene name (s) | rho (Ecogene) | |
| External IDs | ||
| Enzyme classification | ||
| EC, category | 3.6.1. , Helicase | |
| Occurrence | ||
| Parent taxon | Prokaryotes | |
The ρ-factor (rho factor) is a protein which in prokaryotes the RNA - transcription can terminate. It acts as an ATP -dependent helicase that moves along newly synthesized RNA towards the 3 'end and finally detaches the RNA from the DNA and thus terminates the RNA synthesis.
In E. coli , Rho is an approx. 275 kDa hexamer made up of six identical subunits, each of which has an RNA-binding and an ATP-binding domain. The subunits are arranged around a central cavity through which the RNA strand passes. The protein binds to an approximately 70 nucleotide long region of the newly synthesized, single-stranded RNA that is rich in cytosine and poor in guanine . From there, using ATP, the enzyme moves to the transcription bubble , where the RNA is synthesized by the RNA polymerase . Here it acts as a helicase that separates the RNA strand from the DNA and the polymerase.
The binding site, called rut - rho utilization site , is located above the end of the transcription. Various binding sites have been identified without finding a consensus sequence . There may be another specific termination sequence where the polymerase slows down so that it can be overtaken by the Rho factor; however, the kinetics are complex and have not yet been finally analyzed.
literature
- Banerjee S, Chalissery J, Bandey I, Sen R: Rho-dependent transcription termination: more questions than answers . In: J. Microbiol. . 44, No. 1, February 2006, pp. 11-22. PMID 16554712 . PMC 1838574 (free full text).
Individual evidence
- ↑ Interpro: IPR011113 Rho termination factor, RNA binding
- ↑ Bogden CE, Fass D, Bergman N, Nichols MD, Berger JM: The structural basis for terminator recognition by the Rho transcription termination factor . In: Mol. Cell . 3, No. 4, April 1999, pp. 487-93. PMID 10230401 .
- ↑ Richardson JP: Loading Rho to terminate transcription . In: Cell . 114, No. 2, July 2003, pp. 157-9. PMID 12887917 .