Database accession: MF2120020
Name: Factor for inversion stimulation (FIS)
PDB ID: 1ety
Experimental method: X-ray (2.00 Å)
Assembly: homodimer
Source organism: Escherichia coli
Primer publication of the structure:
Cheng YS, Yang WZ, Johnson RC, Yuan HS
Structural analysis of the transcriptional activation region on Fis: crystal structures of six Fis mutants with different activation properties.
(2000) J. Mol. Biol. 302: 1139-51
PMID: 11183780
Abstract:
The Fis protein regulates gene expression in Escherichia coli by activating or repressing transcription of a variety of genes. Fis can activate transcription when bound to DNA upstream of the RNA-polymerase-binding site, such as in the rrnB P1 promoter, or when bound to a site overlapping the -35 RNA polymerase binding site, such as in the proP P2 promoter. It has been suggested that transcriptional activation in both promoters results from interactions between specific amino acids within a turn connecting the B and C helices (the BC turn) in Fis and the C-terminal domain of the alpha-subunit of RNA polymerase (alphaCTD of RNAP). Here, crystal structures of six Fis BC turn mutants with different transcriptional activation properties, Q68A, R71Y, R71L, G72A, G72D and Q74A, were determined at 1.9 to 2.8 A resolution. Two of these mutants, R71Y and R71L, crystallized in unit cells which are different from that of wild-type Fis, and the structure of R71L offers the most complete Fis model to date in that the extended structure of the N-terminal region is revealed. The BC turn in all of these mutant structures remains in a nearly identical gamma gamma beta-turn conformation as present in wild-type Fis. Analyses of the molecular surfaces of the transactivation region of the mutants suggest that several residues in or near the BC turn, including Gln68, Arg71, Gly72 and Gln74, form a ridge that could contact the alphaCTD of RNAP on one side. The structures and biochemical properties of the mutants suggest that Arg71 is the most critical residue for contacting RNAP within this ridge and that the glycine at position 72 helps to stabilize the structure.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
sequence-specific DNA binding Interacting selectively and non-covalently with DNA of a specific nucleotide composition, e.g. GC-rich DNA binding, or with a specific sequence motif or type of DNA e.g. promotor binding or rDNA binding.
transcription factor activity, sequence-specific DNA binding Interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription. The transcription factor may or may not also interact selectively with a protein or macromolecular complex.
Biological process:
transcription, DNA-templated The cellular synthesis of RNA on a template of DNA.
regulation of transcription, DNA-templated Any process that modulates the frequency, rate or extent of cellular DNA-templated transcription.
Cellular component:
cytoplasmic nucleosome A complex comprised of DNA wound around a multisubunit core and associated proteins, which forms the primary packing unit of DNA in the cytoplasm into higher order structures.
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: No modifications of the original PDB file. Chain identifiers are identical with the PDB's identifiers.
Number of unique protein segments: 1
Name: DNA-binding protein Fis
Source organism: Escherichia coli
Length: 89 residues
Sequence:Sequence according to PDB SEQRESVLTVSTVNSQDQVTQKPLRDSVKQALKNYFAQLNGQDVNDLYELVLAEVEQPLLDMVMQYTRGNQTRAALMMGINRGTLRKKLKKYGMN
UniProtKB AC: P0A6R3 (positions: 10-98) Coverage: 90.8%
UniRef90 AC: UniRef90_A8AQG0 (positions: 10-98)
Name: DNA-binding protein Fis
Source organism: Escherichia coli
Length: 93 residues
Sequence:Sequence according to PDB SEQRESVNSDVLTVSTVNSQDQVTQKPLRDSVKQALKNYFAQLNGQDVNDLYELVLAEVEQPLLDMVMQYTRGNQTRAALMMGINRGTLRKKLKKYGMN
UniProtKB AC: P0A6R3 (positions: 6-98) Coverage: 94.9%
UniRef90 AC: UniRef90_A8AQG0 (positions: 6-98)
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Complex evidence:
FIS forms an intertwined homodimer. Equilibrium and kinetic methods have shown that FIS follows a two-step folding reaction where the two unfolded monomers associate to a dimeric intermediate during a fast phase, which is followed by a slower, subsequent folding of the dimeric intermediate to the native dimer (PMID: 14698300).
Structures from the PDB that contain the same number of proteins, and the proteins from the two structures show a sufficient degree of pairwise similarity, i.e. they belong to the same UniRef90 cluster (the full proteins exhibit at least 90% sequence identity) and convey roughly the same region to their respective interactions (the two regions from the two proteins share a minimum of 70% overlap). 