Part:BBa_J03210
malE [Maltose-binding Protein]
| malE encodes the Maltose-binding Protein, essential for both transport and chemotaxis. It resides in the periplasm and undergoes a conformational change on binding to maltose, allowing it to interact with both the transport machinery and chemoreceptors in the cell's inner membrane. |
Usage and Biology
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Maltose, a basic metabolite, is an important energy source for E. coli. It is actively sensed by cells via their natural chemotactic machinery, specifically the Tar Chemoreceptor. Extensive literature provided a very clear picture of the Maltose regulon, a self-contained, tightly regulated set of genes that control maltose uptake, taxis and metabolism. | |
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Above – malE-encoded MPB's role in the maltose transport and taxis system. |
The regulon is made up of three separate operons, all of which contain positive feedback loops that see maltose itself up-regulate the expression of the associated genes for taxis, transport and metabolism. This is done via the maltose-activated malT promoter (malTp), which regulates the expression of malT, a protein that in-turn directly regulates the three separate operons in question. The most significant discovery concerns the key-role of the malE gene, which encodes the maltose-binding protein (MBP). Located in the periplasm, this protein is essential for both maltose transport and chemotaxis. It binds directly with maltose (and its higher homologs, the maltosedextrins), undergoing a conformational change to its structure. As result it is subsequently able to:
In essence, without MBP, a cell is neither able to detect maltose nor use it as an energy source. [The expression of the maltose regulon cannot be induced in the presence of glucose] |
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000INCOMPATIBLE WITH RFC[1000]Illegal BsaI site found at 133
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