TA Pair: YhfG-Fic
#OrganismToxinAntitoxinLocus IDReplicon
1Citrobacter koseri ATCC BAA-8954497 CKO_04783CKO_04784NC_009792
2Cronobacter sakazakii ATCC BAA-8944479 ESA_04372ESA_04371NC_009778
3Escherichia coli 5362809 ECP_3452ECP_3453NC_008253
4Escherichia coli ATCC 87395153 EcolC_0351EcolC_0350NC_010468
5Escherichia coli CFT073678 c4136c4137NC_004431
6Escherichia coli O157:H7 str. EDL933198 Z4722Z4723NC_002655
7Escherichia coli O157:H7 str. Sakai1014 ECs4212ECs4213NC_002695
8Escherichia coli str. K-12 substr. DH10B5175 ECDH10B_3537ECDH10B_3538NC_010473
9Escherichia coli str. K-12 substr. MG16551048 b3361b3362NC_000913
10Klebsiella pneumoniae subsp. pneumoniae MGH 785784247 KPN_03747KPN_03748NC_009648
11Salmonella enterica arizonae serovar 62 z4 z23 RSK29804785 SARI_04145SARI_04144NC_010067
12Salmonella enterica subsp. enterica serovar Agona str. SL4835963 SeAg_B3667SeAg_B3668NC_011149
13Salmonella enterica subsp. enterica serovar Dublin str. CT 020218535978 SeD_A3838SeD_A3839NC_011205
14Salmonella enterica subsp. enterica serovar Paratyphi A str.5952 SSPA3114SSPA3115NC_011147
15Salmonella enterica subsp. enterica serovar Paratyphi A str. ATCC1655 SPA3336SPA3337NC_006511
16Salmonella enterica subsp. enterica serovar Paratyphi B str. SPB74804 SPAB_04317SPAB_04318NC_010102
17Salmonella enterica subsp. enterica serovar Typhimurium str. LT2440 STM3470STM3471NC_003197
18Salmonella enterica subsp. enterica serovar Typhi str. CT18830 STY4326STY4325NC_003198
19Salmonella enterica subsp. enterica serovar Typhi str. Ty2756 t4035t4034NC_004631
20Shigella dysenteriae Sd1972202 SDY_3523SDY_3524NC_007606
21Shigella flexneri 2a str. 2457T725 S4383S4382NC_004741
22Shigella flexneri 2a str. 301650 SF3380SF3381NC_004337
23Shigella flexneri 5 str. 84012823 SFV_3367SFV_3368NC_008258
24Shigella sonnei Ss0461990 SSON_3492SSON_3493NC_007384
AT : is predicted DNA-binding protein; Specific for enteroproteobacteria

Antitoxin domain: YhfG. Protein of unknown function (DUF2559). This family of proteins appear to be restricted to Enterobacteriaceae. The sequences are annotated as yhfG however currently no function is known.

Toxin domain: Fic. Fic/Doc family. This family consists of the Fic (filamentation induced by cAMP) protein and doc (death on curing). The Fic protein is involved in cell division and is suggested to be involved in the synthesis of PAB or folate, indicating that the Fic protein and cAMP are involved in a regulatory mechanism of cell division via folate metabolism. This family contains a central conserved motif HPFXXGNG in most members. The exact molecular function of these proteins is uncertain. P1 lysogens of Escherichia coli carry the prophage as a stable low copy number plasmid. The frequency with which viable cells cured of prophage are produced is about 10(-5) per cell per generation. A significant part of this remarkable stability can be attributed to a plasmid-encoded mechanism that causes death of cells that have lost P1. In other words, the lysogenic cells appear to be addicted to the presence of the prophage. The plasmid withdrawal response depends on a gene named doc (death on curing) that is represented by this family. Doc induces a reversible growth arrest of E. coli cells by targetting the protein synthesis machinery. Doc hosts the C-terminal domain of its antitoxin partner Phd (prevents host death) through fold complementation, a domain that is intrinsically disordered in solution but that folds into an alpha-helix on binding to Doc.

Crystal structure of an HEPN domain protein (TM0613) from Thermotoga maritima at 1.75 A resolution. [PDB ID: 1o3u] [PudMed:14997578]
Structure of HI0074 from Heamophilus Influenzae reveals the fold of a substrate binding domain of a nucleotidyltransferase [PDB ID: 1jog] [PudMed:12486719]
(1) Makarova KS et al. (2009) Comprehensive comparative-genomic analysis of type 2 toxin-antitoxin systems and related mobile stress response systems in prokaryotes. Biol Direct 4:19. [PudMed:19493340] in_silico