My watch list

Gamma thionin


Antifungal protein 1

Identifiers
Symbol	Gamma-thionin
Pfam	PF00304
InterPro	IPR008176
SCOP	1gps
OPM family	61
OPM protein	1jkz
Available PDB structures: 1gpt :1-47 1gps :1-47 1ti5A:28-73 1mr4A:26-72 1n4nA:26-72 1h3rA:28-72 1jkzA:1-46 1myn :27-70 1ayj :2-51 1bk8 :4-50

Gamma-thionins (also known as plant defensins) are small evolutionarily related proteins of plants that serves for their defense from parasites.

Additional recommended knowledge

Essential Laboratory Skills Guide

How to quickly check pipettes?

What is the Correct Way to Check Repeatability in Balances?

The following plant proteins are belong to this family:

Gamma-thionins from Triticum aestivum (Wheat) endosperm (gamma-purothionins) and gamma-hordothionins from Hordeum vulgare(Barley) are toxic to animal cells and inhibit protein synthesis in cell free systems^[1].
A flower-specific thionin (FST) from Nicotiana tabacum (Common Tobacco)^[2].
Antifungal proteins (AFP) from the seeds of Brassicaceae species such as radish, mustard, turnip and Arabidopsis thaliana (Thale Cress)^[3].
Inhibitors of insect alpha-amylases from sorghum^[4].
Probable protease inhibitor P322 from Solanum tuberosum (Potato).
A germination-related protein from Vigna unguiculata (Cowpea)^[5].
Anther-specific protein SF18 from sunflower. SF18 is a protein that contains a gamma-thionin domain at its N-terminus and a proline-rich C-terminal domain.
Glycine max (Soybean) sulphur-rich protein SE60^[6].
Vicia faba (Broad bean) antibacterial peptides fabatin-1 and -2.

In their mature form, these proteins generally consist of about 45 to 50 amino-acid residues. As shown in the following schematic representation, these peptides contain eight conserved cysteines involved in disulphide bonds.

         +-------------------------------------------+
         |          +-------------------+            |
         |          |                   |            |
       xxCxxxxxxxxxxCxxxxxCxxxCxxxxxxxxxCxxxxxxCxCxxxC
                          |   |                | |
                          +---|----------------+ |

'C': conserved cysteine involved in a disulphide bond.

The folded structure of Gamma-purothionin is characterised by a well-defined 3-stranded anti-parallel beta-sheet and a short alpha-helix^[1]. Three disulphide bridges are located in the hydrophobic core between the helix and sheet, forming a cysteine-stabilised alpha-helical motif. This structure differs from that of the plant alpha- and beta-thionins, but is analogous to scorpion toxins and insect defensins.

References

^ ^a ^b Bruix M, Jime nez MA, Santoro J, Gonzalez C, Colilla FJ, Mendez E, Rico M (1993). "Solution structure of gamma 1-H and gamma 1-P thionins from barley and wheat endosperm determined by 1H-NMR: a structural motif common to toxic arthropod proteins". Biochemistry 32 (2): 715-724. PMID 8380707.
^ Gu Q, Kawata EE, Cheung AY, Morse MJ, Wu HM (1992). "A flower-specific cDNA encoding a novel thionin in tobacco". Mol. Gen. Genet. 234 (1): 89-96. PMID 1495489.
^ Osborn RW, Torrekens S, Vanderleyden J, Broekaert WF, Cammue BP, Terras FR, Van Leuven F (1993). "A new family of basic cysteine-rich plant antifungal proteins from Brassicaceae species". FEBS Lett. 316 (3): 233-240. PMID 8422949.
^ Richardson M, Bloch Jr C (1991). "A new family of small (5 kDa) protein inhibitors of insect alpha-amylases from seeds or sorghum (Sorghum bicolar (L) Moench) have sequence homologies with wheat gamma-purothionins". FEBS Lett. 279 (1): 101-104. PMID 1995329.
^ Ishibashi N, Yamauchi D, Minamikawa T (1990). "Stored mRNA in cotyledons of Vigna unguiculata seeds: nucleotide sequence of cloned cDNA for a stored mRNA and induction of its synthesis by precocious germination". Plant Mol. Biol. 15 (1): 59-64. PMID 2103443.
^ Choi Y, Choi YD, Lee JS (1993). "Nucleot ide sequence of a cDNA encoding a low molecular weight sulfur-rich protein in soybean seeds". Plant Physiol. 101 (2): 699-700. PMID 8278516.