| Literature References | 1. OSUNA, R., LIENAU, D., HUGHES, K.T. AND JOHNSON, R.C.
Sequence, regulation, and function of fis in Salmonella typhimurium.
J.BACTERIOL. 177 2021-2032 (1995).
2. WILSON, R.L., LIBBY, S.J., FREET, A.M., BODDICKER, J.D., FAHLEN, T.F.
AND JONES, B.D.
Fis, a DNA nucleoid-associated protein, is involved in Salmonella
typhimurium SPI-I invasion gene expression.
MOL.MICROBIOL. 39 79-88 (2001).
3. GOLDBERG, M.D., JOHNSON, M., HINTON, J.C. AND WILLIAMS, P.H.
Role of the nucleoid-associated protein Fis in the regulation of virulence
properties of enteropathogenic Escherichia coli.
MOL.MICROBIOL. 41 549-559 (2001).
4. MORETT, E. AND BORK, P.
Evolution of new protein function: recombinational enhancer Fis originated
by horizontal gene transfer from the transcriptional regulator NtrC.
FEBS LETT. 433 108-112 (1998).
5. CHENG, Y.S., YANG, W.Z., JOHNSON, R.C. AND YUAN, H.S.
Structural analysis of the transcriptional activation on Fis: crystal
structures of six Fis mutants with different activation properties.
J.MOL.BIOL. 302 1139-1151 (2000).
6. YUAN, H.S., FINKEL, S.E., FENG, J-A., KACZOR-GRZESKOWIAK, M.,
JOHNSON., R.C. AND DICKERSON, R.E.
The molecular structure of wild-type and a mutant Fis protein: Relationship
between mutational changes and recombinational enhancer function or DNA
binding.
PROC.NATL.ACAD.SCI.U.S.A. 88 9558-9562 (1991).
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| Documentation | Transcriptional regulators of prokaryotes play an important role in the
production of several proteins, and in the growth of the cell [1]. By
regulating gene expression, activation or repression of transcription of a
variety of genes can be achieved [1].
The Factor for Inversion Stimulation (FIS) protein is a regulator of
bacterial functions, and binds specifically to weakly related DNA sequences
[1,2]. It activates ribosomal RNA transcription, and is involved in upstream
activation of rRNA promoters. Found in gamma proteobacterial microbes, the
protein has been shown to play a part in the regulation of virulence factors
in both Salmonella typhimurium and Esherichia coli [2,3]. Some of its
functions include inhibition of the initiation of DNA replication from the
OriC site, and promotion of Hin-mediated DNA inversion [3].
In its C-terminal extremity, FIS encodes a helix-turn-helix (HTH) DNA-
binding motif, which shares a high degree of similarity with other HTH
motifs of more primitive bacterial transcriptional regulators, such as the
nitrogen assimilation regulatory proteins (NtrC) from species like Azobacter,
Rhodobacter and Rhizobium. This has led to speculation that both evolved
from a single common ancestor [4].
Recently, the crystal structure of wild-type Escherichia coli FIS was
resolved, together with six mutants [5] - the first crystal structure was
solved in 1991 [6]. From the most recent 2.0A structure [6] of wild-type
FIS, the protein was observed to exist as a homodimer in the bacterial
cytoplasm. By comparison with the structures of FIS mutants, it was deduced
that arginine-71 is critical for the binding of FIS to RNA polymerase, while
glycine-72 stabilises the tertiary structure [6].
DNABINDNGFIS is a 4-element fingerprint that provides a signature for the
DNA-binding protein FIS. The fingerprint was derived from an initial
alignment of 7 sequences: the motifs were drawn from conserved regions
spanning the N-terminal portion of the alignment, prior to the HTH motif -
motif 2 encodes alpha helix 1; and motifs 3 and 4 span helix 2. A single
iteration on SPTR39.22_17.3f was required to reach convergence, no further
sequences being identified beyond the starting set. Two partial matches were
found, both of which are DNA-binding proteins that fail to make significant
matches with one or more motifs.
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