IbpB thermometer
IbpB thermometer | |
---|---|
Conserved secondary structure of the IbpB thermometer | |
Identifiers | |
Symbol | ibpB 5' UTR |
Other data | |
RNA type | RNA thermometer |
Domain(s) | E. coli |
The IbpB thermometer is an RNA thermometer element found in the ibpAB operon.[1] The operon contains two heat-shock genes, encoding inclusion body binding proteins A and B (IbpA/B), and is the most drastically upregulated operon under heat-shock in Escherichia coli.[2]
IbpA is regulated by a ROSE element found in its 5' UTR,[3][4] while IbpB has its own heat-sensitive cis-regulatory element. The activity of this thermoregulator was confirmed in vitro but was not found in vivo, suggesting more complicated operon regulation exists in bacterial cells.[1]
IbpB protein
The IbpB protein, whose expression is regulated by the IbpB thermometer, is 48% identical to IbpA (at the level of amino acid sequence) yet fulfils a different role in heat shock. When IbpB is absent, IbpA protein will form long fibrils which is unusual for a heat shock protein; IbpB, acting as a co-chaperone, inhibits IbpA from forming this structure.[5]
Under heat shock, IbpB protein dissociates to give two smaller subunits and also rearranges its tertiary structure.[6] This "remarkable conformational transformation"[7] is thought to be essential for IbpB to act as a co-chaperone with IbpA under heat shock.[8]
IbpB has been found to retain active for a significant time after a heat shock stimulus has been removed.[7]
References
- 1 2 Gaubig, LC; Waldminghaus, T; Narberhaus, F (Jan 2011). "Multiple layers of control govern expression of the Escherichia coli ibpAB heat-shock operon.". Microbiology (Reading, England). 157 (Pt 1): 66–76. doi:10.1099/mic.0.043802-0. PMID 20864473.
- ↑ Richmond, CS; Glasner, JD; Mau, R; Jin, H; Blattner, FR (Oct 1, 1999). "Genome-wide expression profiling in Escherichia coli K-12.". Nucleic Acids Research. 27 (19): 3821–35. doi:10.1093/nar/27.19.3821. PMC 148645. PMID 10481021.
- ↑ Waldminghaus, T; Gaubig, LC; Klinkert, B; Narberhaus, F (Sep–Oct 2009). "The Escherichia coli ibpA thermometer is comprised of stable and unstable structural elements.". RNA biology. 6 (4): 455–63. doi:10.4161/rna.6.4.9014. PMID 19535917.
- ↑ Waldminghaus, T; Fippinger, A; Alfsmann, J; Narberhaus, F (Dec 2005). "RNA thermometers are common in alpha- and gamma-proteobacteria.". Biological chemistry. 386 (12): 1279–86. doi:10.1515/BC.2005.145. PMID 16336122.
- ↑ Ratajczak, E; Strózecka, J; Matuszewska, M; Zietkiewicz, S; Kuczyńska-Wiśnik, D; Laskowska, E; Liberek, K (Jun 3, 2010). "IbpA the small heat shock protein from Escherichia coli forms fibrils in the absence of its cochaperone IbpB.". FEBS Letters. 584 (11): 2253–7. doi:10.1016/j.febslet.2010.04.060. PMID 20433838.
- ↑ Shearstone, JR; Baneyx, F (Apr 9, 1999). "Biochemical characterization of the small heat shock protein IbpB from Escherichia coli.". The Journal of Biological Chemistry. 274 (15): 9937–45. doi:10.1074/jbc.274.15.9937. PMID 10187768.
- 1 2 Jiao, W; Hong, W; Li, P; Sun, S; Ma, J; Qian, M; Hu, M; Chang, Z (Feb 15, 2008). "The dramatically increased chaperone activity of small heat-shock protein IbpB is retained for an extended period of time after the stress condition is removed.". The Biochemical Journal. 410 (1): 63–70. doi:10.1042/BJ20071120. PMID 17995456.
- ↑ Jiao, W; Qian, M; Li, P; Zhao, L; Chang, Z (Apr 8, 2005). "The essential role of the flexible termini in the temperature-responsiveness of the oligomeric state and chaperone-like activity for the polydisperse small heat shock protein IbpB from Escherichia coli.". Journal of Molecular Biology. 347 (4): 871–84. doi:10.1016/j.jmb.2005.01.029. PMID 15769476.