Tabtoxin

Tabtoxin

Names
Systematic IUPAC name (2S,3R)-2-{(2S)-2-Amino-4-[(3S)-3-hydroxy-2-oxoazetidin-3-yl]butanamido}-3-hydroxybutanoic acid
Other names N-[(2S)-2-Amino-4-[(3S)-3-hydroxy-2-oxo-3-azetidinyl]-1-oxobutyl]-L-threonine; (S)-γ-(3-Hydroxy-2-oxo-3-azetidinyl)-L-α-aminobutyryl-L-threonine
Identifiers
CAS Number	40957-90-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:156429
ChemSpider	96964 Y
PubChem CID	107817
UNII	H3YX70R64N Y
CompTox Dashboard (EPA)	DTXSID70961331
InChI InChI=1S/C11H19N3O6/c1-5(15)7(9(17)18)14-8(16)6(12)2-3-11(20)4-13-10(11)19/h5-7,15,20H,2-4,12H2,1H3,(H,13,19)(H,14,16)(H,17,18)/t5-,6+,7+,11+/m1/s1 Y
SMILES O=C(O)[C@@H](NC(=O)[C@@H](N)CC[C@@]1(O)C(=O)NC1)[C@H](O)C
Properties
Chemical formula	C11H19N3O6
Molar mass	289.288 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Tabtoxin, also known as wildfire toxin, is a simple monobactam phytotoxin produced by Pseudomonas syringae. It is the precursor to the antibiotic tabtoxinine β-lactam (TBL).^[1] It is produced by:

• Pseudomonas syringae pv. tabaci, the causal agent of the wildfire of tobacco.
• P. syringae pv. coronafaciens
• P. syringae pv. garcae
• P. syringae BR2, causes a disease of bean (Phaseolus vulgaris) similar to tobacco wildfire. This organism is closely related to P. syringae pv. tabaci but cannot be classified in the pathovar tabaci because it is not pathogenic on tobacco.

Tabtoxin is a dipeptide precursor to the biologically active form of TBL, differing by having an extra threonine attached by a peptide bond to the C terminus. Tabtoxin is required by BR2(R) for both chlorosis and lesion formation on bean. All mutations that affected tabtoxin production, whether spontaneous deletion or transposon induced, also affected lesion formation, and in all cases, restoration of tabtoxin production also restored pathogenic symptoms. Other factors may be required for BR2 to be pathogenic on bean, but apparently these are in addition to tabtoxin production.^[2][3] TBL functions as a toxin by inhibition of glutamine synthetase.