User:Rchan255/sandbox: Difference between revisions
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===Regulatory Structures=== |
===Regulatory Structures=== |
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Upstream of the three afore-mentioned structural genes, the ''gal'' operon has two overlapping [[promoters]], in the order in which they appear; P<sub>2</sub> and P<sub>1</sub><ref name="Meher&Orosz&Adhya" />. The two transcription initiation sites linked to the two promoters are 5 base pairs apart and are different in sequence<ref name="Ji&Jeon">{{cite journal|last1=Ji|first1=Sang Chun|last2=Jeon|first2=Heung Jin|last3=Yun|first3=Sang Hoon|last4=Lee|first4=Hee Jung|last5=Lim|first5=Heon M.|title=Quantification of the galactose-operon mRNAs 5 bases different in their 5’-ends|journal=BMB Reports|date=July 2010|volume=43|issue=7|page=474-479|pmid=20663408|url=http://bmbreports.org/jbmb/jbmb_files/%5B43-7%5D1007271301_(474-479)BMB361(10-103).pdf}}</ref>. |
Upstream of the three afore-mentioned structural genes, the ''gal'' operon has two overlapping [[promoters (genetics)|promoters]], in the order in which they appear; P<sub>2</sub> and P<sub>1</sub><ref name="Meher&Orosz&Adhya" />. The two transcription initiation sites linked to the two promoters are 5 base pairs apart and are different in sequence<ref name="Ji&Jeon">{{cite journal|last1=Ji|first1=Sang Chun|last2=Jeon|first2=Heung Jin|last3=Yun|first3=Sang Hoon|last4=Lee|first4=Hee Jung|last5=Lim|first5=Heon M.|title=Quantification of the galactose-operon mRNAs 5 bases different in their 5’-ends|journal=BMB Reports|date=July 2010|volume=43|issue=7|page=474-479|pmid=20663408|url=http://bmbreports.org/jbmb/jbmb_files/%5B43-7%5D1007271301_(474-479)BMB361(10-103).pdf}}</ref>. |
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As well, the ''gal'' operon is associated with two [[operators]], in the order in which they appear; O<sub>E</sub> and O<sub>I</sub>. These two operators are separated by 113 base pairs, straddling both the promoters and transcription initiation sites with O<sub>E</sub> appearing at the beginning of the operon, and O<sub>I</sub> appearing a few base pairs upstream of the first structural gene''galE''. |
As well, the ''gal'' operon is associated with two [[operators]], in the order in which they appear; O<sub>E</sub> and O<sub>I</sub>. These two operators are separated by 113 base pairs, straddling both the promoters and transcription initiation sites with O<sub>E</sub> appearing at the beginning of the operon, and O<sub>I</sub> appearing a few base pairs upstream of the first structural gene''galE''. |
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Revision as of 03:54, 12 November 2015
Remember to keep to an encyclopedic style that is accessible. Good references but try to find something more recent too. BenjaminLaufer (talk) 15:49, 4 November 2015 (UTC)
The gal operon (galactose operon) is a prokaryotic operon necessary for galactose transport and metabolism in Escherichia coli, and many other bacteria including those within the Streptomyces genus. Although galactose is not the preferred carbon source in bacteria, D-galactose (one of two possible isomers) is important in E. coli as a building block for other cellular pathways[1] (ie. lactose synthesis, glucose conversion via the Leloir pathway, etc.). The gal operon contains genes coding for the enzymes necessary in this galactose to glucose conversion as well as the controls necessary for this process[2].
 | This is a user sandbox of Rchan255. A user sandbox is a subpage of the user's user page. It serves as a testing spot and page development space for the user and is not an encyclopedia article. |
Gal Operon Structure
Structural Genes
Bacterial operons are polycistronic, meaning multiple gene products can be translated from one mRNA transcript. The gal operon possesses three structural genes, in the order in which they appear: galE, galT, and galk[3]. As a result, whenever galactose metabolism is needed, the gal operon will be transcribed and the three gene products will then be translated. The three genes and their products are as follows:
- galE is the first gene to appear in the gal operon and codes for the enzyme UDP-Galactose-4-Epimerase, or GALE, which assists the conversion of UDP-galactose to UDP-glucose
- galT is the second gene to appear in the gal operon and codes for the enzyme Galactose-1-Phosphat-Uridyl-Transferase, or GALT, which assists the conversion of Galactose-1-P to UDP-Galactose
- galK is the third gene to appear in the gal operon and codes for the enzyme Galactokinase, which phosphorylates Galactose to Galactose-1-P[2].
The order of the genes, however, do not align with the order in which the respective gene products function in the galactose metabolic pathway. Instead, the gene product of galK (Galactokinase)- functions first, the gene product of galT (GALT) functions second, and the gene product of galE (GALE) functions third. Thus, the gene products of the three structural genes in the gal operon function in reverse order in which they appear.
Regulatory Structures
Upstream of the three afore-mentioned structural genes, the gal operon has two overlapping promoters, in the order in which they appear; P2 and P1[3]. The two transcription initiation sites linked to the two promoters are 5 base pairs apart and are different in sequence[4].
As well, the gal operon is associated with two operators, in the order in which they appear; OE and OI. These two operators are separated by 113 base pairs, straddling both the promoters and transcription initiation sites with OE appearing at the beginning of the operon, and OI appearing a few base pairs upstream of the first structural genegalE.
References
1. The galactose regulon of Escherichia coli- [1]
2. Regulation of open complex formation at the Escherichia coli galactose operon promoters: Simultaneous interaction of RNA polymerase, gal repressor and CAP/cAMP- [5]
3. Regulation of the gal Operon of Escherichia coli by the capR Gene*- [6]
4. A control element within a structural gene: The gal operon of Escherichia coli- [3]
5. Control of transcription termination- [7]
6. Regulatory sequences involved in the promotion and termination of RNA transcription- [8]
7. Two promoters, one inducible and one constitutive, control transcription of the Streptomyces lividans galactose operon- [9]
8. Galactose Operon- [2]
9. Quantification of the galactose-operon mRNAs 5 bases different in their 5’-ends[4]
- ^ a b Weickert, Michael J.; Adhya, Sankar (1993). "The galactose regulon of Escherichia coli". Molecular Microbiology. 10 (2): 245-251. doi:10.1111/j.1365-2958.1993.tb01950.x.
- ^ a b c {cite web|title=Galactose Operon|url=http://www.spektrum.de/lexikon/biologie/galactose-operon/26298%7Cwebsite=Spektrum der Wissenschaft|publisher=Spektrum Akademischer Verlag|accessdate=11 November 2015}}
- ^ a b c Irani, Meher H.; Orosz, Laszlo; Adhya, Sankar (March 1983). "A control element within a structural gene: The gal operon of Escherichia coli". Cell. 32 (3): 783-788. doi:10.1016/0092-8674(83)90064-8.
- ^ a b Ji, Sang Chun; Jeon, Heung Jin; Yun, Sang Hoon; Lee, Hee Jung; Lim, Heon M. (July 2010). "Quantification of the galactose-operon mRNAs 5 bases different in their 5'-ends" (PDF). BMB Reports. 43 (7): 474-479. PMID 20663408.
- ^ Goodrich, James A.; McClure, William R. (1992). "Regulation of open complex formation at the Escherichia coli galactose operon promoters: Simultaneous interaction of RNA polymerase, gal repressor and CAP/cAMP". Journal of Molecular Biology. 224 (1): 15-29. doi:10.1016/0022-2836(92)90573-3.
- ^ Mackie, George; Wilson, David B. (May 25, 1972). "Regulation of the gal Operon of Escherichia coli by the capR Gene*". The Journal of Biological Chemistry. 247 (10): 2973-2978.
- ^ Adhya, Sankar; Gottesman, Max (1978). "Control of transcription termination". Annual Review of Biochemistry. 47: 967-996. doi:10.1146/annurev.bi.47.070178.004535.
- ^ Rosenberg, Martin; Court, Donald (1979). "Regulatory sequences involved in the promotion and termination of RNA transcription". Annual Review of Biochemistry. 13: 319-353. doi:10.1146/annurev.ge.13.120179.001535.
- ^ Fornwald, James A.; Schmidt, Francis J.; Adams, Craig W.; Rosenberg, Martin; Brawner, Mary E. (April 1987). "Two promoters, one inducible and one constitutive, control transcription of the Streptomyces lividans galactose operon" (PDF). Proceedings of the National Academy of Sciences. 84: 2130-2134. PMID 3031664.
