<p> The C-terminal domain of several bacterial transcriptional repressors show structural homology to one another. These domains are characterised by an SH3-like structure consisting of a partly opened beta-barrel, where the last strand is interrupted by a 3-10 helical turn. The C-terminal domain displays a metal-binding function in DTXR and IDER and may act to stabilising the dimeric form of the <taxon tax_id="562">Escherichia coli</taxon> KorB repressor, thereby enhancing specific operator binding by the repressor. The N-terminal region of these proteins is responsible for binding DNA. </p><p> Proteins containing this C-terminal domain include: the E. coli biotin repressor BirA, which has the dual role of a transcriptional repressor of the biotin operator and a biotin-activating enzyme [<cite idref="PUB00004803"/>, <cite idref="PUB00010706"/>]; the E. coli RP4 plasmid regulatory protein KorB, which regulates the expression of plasmid genes whose products are involved in the replication, transfer, and inheritance of RP4 [<cite idref="PUB00010707"/>]; and the diphtheria toxin repressor (DTXR), along with its homologues in the pathogenic bacteria causing tuberculosis (IDER), leprosy, syphilis, and staphylococcal infections, which play important roles in regulating virulence-associated genes [<cite idref="PUB00010708"/>, <cite idref="PUB00010709"/>]. </p> Transcriptional repressor, C-terminal