| Type: | Family | Name: | DNA-binding protein Fis |
| Description: | The Factor for Inversion Stimulation (FIS) protein is a regulator of bacterial functions, and binds specifically to weakly related DNA sequences []. It activates ribosomal RNA transcription, and is involved in upstreamactivation of rRNA promoters. Found in gamma proteobacterial microbes, the protein has been shown to play a part in the regulation of virulence factorsin both Salmonella typhimuriumand Escherichia coli[]. Some of itsfunctions include inhibition of the initiation of DNA replication from the OriC site, and promotion of Hin-mediated DNA inversion [].In its C-terminal extremity, FIS encodes a helix-turn-helix (HTH) DNA- binding motif, which shares a high degree of similarity with other HTHmotifs 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 []. Recently, the crystal structure of wild-type E. coli FIS was resolved, together with six mutants [] - the first crystal structure wassolved in 1991. From the most recent 2.0A structure [] of wild-typeFIS, the protein was observed to exist as a homodimer in the bacterial cytoplasm. By comparison with the structures of FIS mutants, it was deducedthat arginine-71 is critical for the binding of FIS to RNA polymerase, while glycine-72 stabilises the tertiary structure. | Short Name: | Fis_DNA-bd |
