TA Pair: MerR-PIN
#OrganismToxinAntitoxinLocus IDReplicon
1Acidiphilium cryptum JF-53910 Acry_3278Acry_3279NC_009467
2Acidithiobacillus ferrooxidans ATCC 539935993 Lferr_0233Lferr_0234NC_011206
3Acidovorax sp. JS423409 Ajs_1588Ajs_1587NC_008782
4Acidovorax sp. JS423407 Ajs_1266Ajs_1265NC_008782
5Cupriavidus metallidurans CH342650 Rmet_2343Rmet_2344NC_007973
6Cupriavidus taiwanensis LMG 194245301 pRALTA_0073pRALTA_0072NC_010529
7Cyanothece sp. ATCC 511425329 cce_2688cce_2689NC_010546
8Frankia sp. CcI32383 Francci3_1857Francci3_1856NC_007777
9Gloeobacter violaceus PCC 74211435 glr1723glr1722NC_005125
10Granulibacter bethesdensis CGDNIH12892 GbCGDNIH1_1595GbCGDNIH1_1594NC_008343
11Hahella chejuensis KCTC 23962304 HCH_06453HCH_06454NC_007645
12Janthinobacterium sp. Marseille4283 mma_2686mma_2687NC_009659
13Kocuria rhizophila DC22015444 KRH_05180KRH_05190NC_010617
14Legionella pneumophila str. Corby4001 LPC_2191LPC_2192NC_009494
15Magnetococcus marinus MC-13142 Mmc1_0694Mmc1_0695NC_008576
16Marinomonas sp. MWYL14266 Mmwyl1_3977Mmwyl1_3978NC_009654
17Methylococcus capsulatus str. Bath1720 MCA2638MCA2639NC_002977
18Mycobacterium bovis AF2122/971177 Mb3775cMb3776cNC_002945
19Mycobacterium bovis BCG str. Pasteur 1173P23385 BCG_3808cBCG_3809cNC_008769
20Mycobacterium tuberculosis CDC1551293 MT3856MT3857NC_002755
21Mycobacterium tuberculosis F114185 TBFG_13781TBFG_13782NC_009565
22Mycobacterium tuberculosis H37Ra4139 MRA_3787MRA_3788NC_009525
23Mycobacterium tuberculosis H37Rv133 Rv3749cRv3750cNC_000962
24Mycobacterium ulcerans Agy993174 MUL_0510MUL_0509NC_008611
25Nocardia farcinica IFM 101521084 nfa10020nfa10030NC_006361
26Polaromonas naphthalenivorans CJ23403 Pnap_3977Pnap_3978NC_008781
27Polaromonas sp. JS6662589 Bpro_4762Bpro_4763NC_007948
28Proteus mirabilis HI43205362 PMI2326PMI2325NC_010554
29Pseudomonas putida KT2440313 PP_4152PP_4151NC_002947
30Rhizobium etli CFN 421772 RHE_PD00154RHE_PD00155NC_004041
31Rhodococcus jostii RHA12833 RHA1_ro03507RHA1_ro03506NC_008268
32Rhodococcus jostii RHA12842 RHA1_ro10375RHA1_ro10374NC_008270
33Rhodopseudomonas palustris BisB182538 RPC_4423RPC_4424NC_007925
34Shewanella baltica OS1553536 Sbal_4436Sbal_4435NC_009036
35Thermus thermophilus HB271609 TTC0799TTC0798NC_005835
36Thermus thermophilus HB81374 TTHA1163TTHA1162NC_006461
37Verminephrobacter eiseniae EF01-23455 Veis_4163Veis_4162NC_008786
AT: truncated MerR

Antitoxin domain: MerR. HTH_MerR-SF: Helix-Turn-Helix DNA binding domain of transcription regulators from the MerR superfamily. Helix-turn-helix (HTH) transcription regulator MerR superfamily, N-terminal domain. The MerR family transcription regulators have been shown to mediate responses to stress including exposure to heavy metals, drugs, or oxygen radicals in eubacterial and some archaeal species. They regulate transcription of multidrug/metal ion transporter genes and oxidative stress regulons by reconfiguring the spacer between the -35 and -10 promoter elements. A typical MerR regulator is comprised of two distinct domains that harbor the regulatory (effector-binding) site and the active (DNA-binding) site. Their N-terminal domains are homologous and contain a DNA-binding winged HTH motif, while the C-terminal domains are often dissimilar and bind specific coactivator molecules such as metal ions, drugs, and organic substrates.

Toxin domain: PIN. This PIN (PilT N terminus) domain is a compact domain of about 100 amino acids. The domain has two nearly invariant aspartates. The function of the PIN domain is unknown but a role in signaling appears likely given the presence of this domain is StbB and DIS3. The majority of PIN-domain proteins found in prokaryotes are the toxic components of toxin-antitoxin operon, and toxin-antitoxin gene cassettes, though first found in plasmids, are found to be abundant in free-living prokaryotes, including many pathogenic bacteria. These loci provide a control mechanism that helps free-living prokaryotes cope with nutritional stress. In many genomes PIN domains are annotated as VapC and are part of the VapBC toxin-antitoxin operons. These operons are expanded in number in several unrelated micro-organisisms including Mycobacterium tuberculosis and Sulfolobus solfataricus.

Structure of DocH66Y in complex with the C-terminal domain of Phd [PDB ID: 3DD7] [PudMed:18757857]
Crystal structure of (YP_321193.1) from Anabaena variabilis ATCC 29413 at 2.00 A resolution [PDB ID: 2GA1]
(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