L-arabinose operon

The L-arabinose operon, also called the ara or araBAD operon, is an operon required for the breakdown of the five-carbon sugar L-arabinose in Escherichia coli.[1] The L-arabinose operon contains three structural genes: araB, araA, araD (collectively known as araBAD), which encode for three metabolic enzymes that are required for the metabolism of L-arabinose.[2] AraB (ribulokinase), AraA (an isomerase), and AraD (an epimerase) produced by these genes catalyse conversion of L-arabinose to an intermediate of the pentose phosphate pathway, D-xylulose-5-phosphate.[2]

The structural genes of the L-arabinose operon are transcribed from a common promoter into a single transcript, a mRNA.[3] The expression of the L-arabinose operon is controlled as a single unit by the product of regulatory gene araC and the catabolite activator protein (CAP)-cAMP complex.[4] The regulator protein AraC is sensitive to the level of arabinose and plays a dual role as both an activator in the presence of arabinose and a repressor in the absence of arabinose to regulate the expression of araBAD.[5] AraC protein not only controls the expression of araBAD but also auto-regulates its own expression at high AraC levels.[6]

  1. ^ Voet, Donald & Voet, Judith G. (2011). Biochemistry (4th. ed.). Hoboken, NJ: John Wiley & Sons. pp. 1291–1294. ISBN 978-0470-57095-1.{{cite book}}: CS1 maint: multiple names: authors list (link)
  2. ^ a b Schleif, Robert (2000). "Regulation of the L-arabinose operon of Escherichia coli". Trends in Genetics. 16 (12): 559–565. doi:10.1016/S0168-9525(00)02153-3. PMID 11102706.
  3. ^ Watson, James D. (2008). Molecular biology of the gene (6th. ed.). Harlow: Addison-Wesley. pp. 634–635. ISBN 9780321507815.
  4. ^ Schleif, Robert (2010). "AraC protein, regulation of the l-arabinose operon in, and the light switch mechanism of AraC action". FEMS Microbiology Reviews. 34 (5): 779–796. doi:10.1111/j.1574-6976.2010.00226.x. PMID 20491933.
  5. ^ Lobell, R. B.; Schleif, R. F. (1990). "DNA looping and unlooping by AraC protein". Science. 250 (4980): 528–532. Bibcode:1990Sci...250..528L. doi:10.1126/science.2237403. PMID 2237403. S2CID 25017204.
  6. ^ Schleif, Robert (2003). "AraC protein: A love-hate relationship". BioEssays. 25 (3): 274–282. doi:10.1002/bies.10237. PMID 12596232.