Fis Promoter Map

The image above will vary in width to fit the size of your browser window. The figure is also available as: Fis Promoter Map (PDF), Fis Promoter Map (jpg)

At the top, under the page number, you see the line that begins with 'piece 1 ...' which describes the graph. Below that is a bunch of numbers which are the positions of DNA bases on the chromosome of the Escherichia coli (E. coli) bacterial genome. So this is a place at 3.4 million bases from the (arbitrary!) start of the coordinate system, out of 4.6 million bases.

I picked this place because it is just in front of the fis gene. The fis gene is turned on when a bacterial cell goes from being starved, when there are no Fis protein molecules, to having lots of nutrients, the number is then 50,000 Fis molecules in each cell!

The letters over pink and red rectangles are representing Fis sites. I call the letters 'sequence walkers' - we have a patent on the method. The colored rectangles, show how strong the site should be (using the mathematics of information theory). The cool thing about this new 'instrument' is that you can see which sites are strong and which are weak in a instant. Before now you had to read the labels, like 4.8 bits or 1.0 bits.

But I also like it because one can see so much in an instant.

See those blue and green rectangles? They come in pairs, and there are dashed lines directly below the green bar of each that connect them. These represent the places RNA polymerase binds to the DNA to start making RNA. The RNA runs into the fis gene (and from that the Fis protein itself is made) and so this is the genetic control region for Fis.

The reason I love this region is that how it works is obvious. If the cell makes too much Fis protein (from the fis gene) then Fis protein will bind all over this region and turn off the promoters! So it is a nifty feed-back loop, and you can see that in an instant from this ... artwork :-)




Schneider Lab
origin: 2004 Jul 27
updated: 2007 May 30