type II toxin-antitoxin system VapB family antitoxin; The term VapB has been used for the antitoxin component of various type II toxin-antitoxin systems called VapBC but showing little or no sequence identity. The family described here includes member proteins such as STM3034 from Salmonella enterica LT2 and VapB2 from Haemophilus influenzae, and is seeming unrelated to proteins called VapB in Mycobacterium tuberculosis.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 447184020  4 VSIFKNGNNRAIRLPRDLDFDG-VSELEIVREGDSIILRPVRPTWGSFAQLDRADPDFMAEREDVVSDEgRFE 75
Cdd:NF040493  1 AKVFKNNRSQAVRLPKEVRFPGdVKEVEIRRVGDERILRPVRPSWDSFFDGPSVSDDFMAEREQPEQQE-REA 72

type II toxin-antitoxin system VapB family antitoxin; The term VapB has been used for the antitoxin component of various type II toxin-antitoxin systems called VapBC but showing little or no sequence identity. The family described here includes member proteins such as STM3034 from Salmonella enterica LT2 and VapB2 from Haemophilus influenzae, and is seeming unrelated to proteins called VapB in Mycobacterium tuberculosis.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 447184020  4 VSIFKNGNNRAIRLPRDLDFDG-VSELEIVREGDSIILRPVRPTWGSFAQLDRADPDFMAEREDVVSDEgRFE 75
Cdd:NF040493  1 AKVFKNNRSQAVRLPKEVRFPGdVKEVEIRRVGDERILRPVRPSWDSFFDGPSVSDDFMAEREQPEQQE-REA 72

SpoVT / AbrB like domain; This domain is found in AbrB from Bacillus subtilis. The product of the abrB gene is an ambiactive repressor and activator of the transcription of genes expressed during the transition state between vegetative growth and the onset of stationary phase and sporulation. AbrB is thought to interact directly with the transcription initiation regions of genes under its control. AbrB contains a helix-turn-helix structure, but this domain ends before the helix-turn-helix begins. The product of the B. subtilis gene spoVT is another member of this family and is also a transcriptional regulator. DNA-binding activity in this AbrB homologue requires hexamerisation. Another family member has been isolated from the Sulfolobus solfataricus and has been identified as a homologue of bacterial repressor-like proteins. The Escherichia coli family member SohA or Prl1F appears to be bifunctional and is able to regulate its own expression as well as relieve the export block imposed by high-level synthesis of beta-galactosidase hybrid proteins.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 447184020    7 FKNGNNRAIRLPRD----LDFDGVSELEIVREGDSIILRPVRPTW 47
Cdd:smart00966  1 VKVGNSGQVTIPKEvrekLGIKEGDEVELEVDGDGIILEPVKKAP 45

type II toxin-antitoxin system VapB family antitoxin; The term VapB has been used for the antitoxin component of various type II toxin-antitoxin systems called VapBC but showing little or no sequence identity. The family described here includes member proteins such as STM3034 from Salmonella enterica LT2 and VapB2 from Haemophilus influenzae, and is seeming unrelated to proteins called VapB in Mycobacterium tuberculosis.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 447184020  4 VSIFKNGNNRAIRLPRDLDFDG-VSELEIVREGDSIILRPVRPTWGSFAQLDRADPDFMAEREDVVSDEgRFE 75
Cdd:NF040493  1 AKVFKNNRSQAVRLPKEVRFPGdVKEVEIRRVGDERILRPVRPSWDSFFDGPSVSDDFMAEREQPEQQE-REA 72

Antitoxin component MazE of the MazEF toxin-antitoxin module [Defense mechanisms];

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                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 447184020  1 MRTvSIFKNGNNRAIRLPRD----LDFDGVSELEIVREGDSIILRPVRPTWGSFAQL-DRADPDFMAEREDVVSDEGR 73
Cdd:COG2336   1 MTT-KIRKWGNSLGVRIPKAlleqLGLKEGDEVELEVEDGRIVIRPVRRPRYTLEELlAGITPENAHEEYDWGKPVGK 77

Antidote-toxin recognition MazE, bacterial antitoxin; AbrB-like is a family of small proteins that operate in conjunction with a cognate toxin molecule. The commonly attributed role of toxin-antitoxin systems is to maintain low-copy number plasmids from one generation to the next. Such gene-pairs are also found on chromosomes and to be associated with a number of biological functions such as: reduction of protein synthesis, gene regulation and retardation of cell growth under nutritional stress. This family includes proteins from a number of different pairings, eg MazE, AbrB, VapB, PhoU, PemI-like and SpoVT. MazE is the antidote to the toxin MazF of E. coli. MazE-MazF in E. coli is a regulated prokaryotic chromosomal addiction module. MazE antidote is degraded by the ClpPA protease of the bacterial proteasome. MazE-MazF is thought to play a role in programmed cell death when cells suffer nutrient deprivation, and MazE-MazF modules have also been implicated in the bacteriostatic effects of other addiction modules.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|...
gi 447184020   7 FKNGNNRAIRLP----RDLDFDGVSELEIVREGDSIILRPVRP 45
Cdd:pfam04014  1 FKVGNSGAVRIPkevrKALGIKEGDEVELEVDGDKIILKPKKS 43