fis is the E. coli gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

 encoding FIS

FIS (protein)

FIS is a nucleoid-associated protein in E. coli. It is highly expressed from fis gene from the end of the stationary phase till the mid-exponential phase. It is a DNA binding protein. It affects the topology and supercoiling of E. coli chromosome, and it regulates the expression of many other...

 protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

. The regulation of this gene is more complex

Complexity

In general usage, complexity tends to be used to characterize something with many parts in intricate arrangement. The study of these complex linkages is the main goal of complex systems theory. In science there are at this time a number of approaches to characterizing complexity, many of which are...

 than most other genes in the E. coli genome

Genome

In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....

, as FIS is an important protein which regulates expression

Gene expression

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...

 of other genes. It is supposed that fis is regulated by H-NS, IHF (protein) and CRP

CAMP receptor protein

cAMP receptor protein is a regulatory protein in bacteria. This protein binds cAMP, which causes a conformational change that allows the protein to bind tightly to a specific DNA sequence in the promoters of the genes it controls...

. It also regulates its own expression (autoregulation

Autoregulation

Autoregulation is a process within many biological systems, resulting from some internal adaptive mechanism that works to adjust the systems response to stimuli. While most systems of the body show some degree of autoregulation, it is most clearly observed in the kidney, the heart, and the brain...

).

FIS buffers decrease of negative supercoiling in tyrT and rrnA expression. The upstream FIS binding site of rrnA is required for this and it's probable that FIS enables local DNA curvature. See Travers and Muskhelishvili 2005 for more detail.