Plant defensin

Plant defensins (formerly gamma-thionins) are a family of small, cysteine-rich defensins found in plants that serve to defend them against pathogens and parasites.[1]

Plant defensin
The plant defensin NaD1 with alpha helix in red, beta strands in blue, disulphide bonds in yellow (PDB: 1mr4​)
Identifiers
SymbolPlant defensin
PfamPF00304
Pfam clanCL0054
InterProIPR008176
PROSITEPDOC00725
SCOP21gps / SCOPe / SUPFAM
OPM superfamily58
OPM protein1jkz
CDDcd00107

History

The first plant defensins were discovered in barley and wheat in 1990 and were initially designated as a γ-thionins.[2][3] In 1995 the name was changed to 'plant defensin' when it was identified that they are evolutionarily unrelated to other thionins and were more similar to defensins from insects and mammals.[4][5]

Function

Plant defensins are a large component of the plant innate immune system. A plant genome typically contains large numbers of different defensin genes[6] that vary in their efficacies against different pathogens and the amount they are expressed in different tissues.[7]

Antimicrobial activity

Most characterised plant defensins are antimicrobial peptides. Both antifungal and antibacterial plant defensins have been identified,[8][9] although their exact mechanisms of action vary.[7]

Enzyme inhibition

Some plant defensins have also been identified as enzyme inhibitors of α-amylase or trypsin.[10][11][12] It is believed that these are antifeedant activities to deter insects.[11]

Anti-cancer

An additional promiscuous activity of some plant defensins is stopping the growth or disrupting the membranes of cancer cells in in vitro experiments.[13][14]

Structure
Secondary structure of main types of plant defensins (with cysteines numbered). The 8-cysteine variant is the most common. Alpha helix in red, beta strands in blue, disulphide bonds in yellow.

Defensin proteins are produced as a precursor protein with one or two prodomains that are removed to make the final mature protein. In their mature form, they generally consist of about 45 to 50 amino-acid residues. The folded structure is characterised by a well-defined 3-stranded anti-parallel beta-sheet and a short alpha-helix.[15] The structure of most plant defensins is cross-linked by four disulfide bridges: three in core and one linking the N- and C-termini.[1] Some plant defensins have only the core three disulphides, and a few have been found with an additional one (resulting in five total bridges).[16]

Evolution

Plant defensins are members of the protein superfamily called the cis-defensins or CSαβ fold.[17] This superfamily includes arthropod defensins and fungal defensins (but not defensins found in mammals). It also includes several families of proteins not involved in the immune system, including plant S-locus 11 proteins involved in self-incompatibility during reproduction, and toxin proteins in scorpion venoms.[18][19]

Examples

The following plant proteins belong to this family:

  • The flower-specific Nicotiana alata defensin (NaD1)
  • 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.[15]
  • A flower-specific thionin (FST) from Nicotiana tabacum (Common Tobacco).[20]
  • Antifungal proteins (AFP) from the seeds of Brassicaceae species such as radish, mustard, turnip and Arabidopsis thaliana (Thale Cress).[21]
  • Inhibitors of insect alpha-amylases from sorghum.[22]
  • Probable protease inhibitor P322 from Solanum tuberosum (Potato).
  • A germination-related protein from Vigna unguiculata (Cowpea).[23]
  • 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) sulfur-rich protein SE60.[24]
  • Vicia faba (Broad bean) antibacterial peptides fabatin-1 and -2.

Databases

A database for antimicrobial peptides, including defensins is available: PhytAMP (http://phytamp.hammamilab.org).[25]

References
  1. Parisi, Kathy; Shafee, Thomas M.A.; Quimbar, Pedro; van der Weerden, Nicole L.; Bleackley, Mark R.; Anderson, Marilyn A. (April 2019). "The evolution, function and mechanisms of action for plant defensins". Seminars in Cell & Developmental Biology. 88: 107–118. doi:10.1016/j.semcdb.2018.02.004. PMID 29432955.
  2. MENDEZ, Enrique; MORENO, Aurora; COLILLA, Francisco; PELAEZ, Fernando; LIMAS, Gabriel G.; MENDEZ, Raul; SORIANO, Fernando; SALINAS, Matilde; HARO, Cesar (December 1990). "Primary structure and inhibition of protein synthesis in eukaryotic cell-free system of a novel thionin, gamma-hordothionin, from barley endosperm". European Journal of Biochemistry. 194 (2): 533–539. doi:10.1111/j.1432-1033.1990.tb15649.x. ISSN 0014-2956. PMID 2176600.
  3. Colilla, Francisco J.; Rocher, Asuncion; Mendez, Enrique (1990-09-17). "γ-Purothionins: amino acid sequence of two polypeptides of a new family of thionins from wheat endosperm". FEBS Letters. 270 (1–2): 191–194. doi:10.1016/0014-5793(90)81265-p. ISSN 0014-5793. PMID 2226781. S2CID 9260786.
  4. Broekaert, W. F.; Terras, Frg; Cammue, Bpa; Osborn, R. W. (1995-08-01). "Plant Defensins: Novel Antimicrobial Peptides as Components of the Host Defense System". Plant Physiology. 108 (4): 1353–1358. doi:10.1104/pp.108.4.1353. ISSN 0032-0889. PMC 157512. PMID 7659744.
  5. Terras, F. R.; Eggermont, K.; Kovaleva, V.; Raikhel, N. V.; Osborn, R. W.; Kester, A.; Rees, S. B.; Torrekens, S.; Leuven, F. Van; Vanderleyden, J. (1995-05-01). "Small cysteine-rich antifungal proteins from radish: their role in host defense". The Plant Cell. 7 (5): 573–588. doi:10.1105/tpc.7.5.573. ISSN 1040-4651. PMC 160805. PMID 7780308.
  6. Silverstein, Kevin A.T.; Moskal, William A.; Wu, Hank C.; Underwood, Beverly A.; Graham, Michelle A.; Town, Christopher D.; VandenBosch, Kathryn A. (2007-06-12). "Small cysteine-rich peptides resembling antimicrobial peptides have been under-predicted in plants". The Plant Journal. 51 (2): 262–280. doi:10.1111/j.1365-313x.2007.03136.x. ISSN 0960-7412. PMID 17565583.
  7. Anderson, F. T. Lay and M. A. (2005-01-31). "Defensins - Components of the Innate Immune System in Plants". Current Protein & Peptide Science. 6 (1): 85–101. doi:10.2174/1389203053027575. PMID 15638771. Retrieved 2020-11-28.
  8. Cools, Tanne L; Struyfs, Caroline; Cammue, Bruno PA; Thevissen, Karin (April 2017). "Antifungal plant defensins: increased insight in their mode of action as a basis for their use to combat fungal infections". Future Microbiology. 12 (5): 441–454. doi:10.2217/fmb-2016-0181. ISSN 1746-0913. PMID 28339295.
  9. Sathoff, Andrew E.; Samac, Deborah A. (May 2019). "Antibacterial Activity of Plant Defensins". Molecular Plant-Microbe Interactions. 32 (5): 507–514. doi:10.1094/mpmi-08-18-0229-cr. ISSN 0894-0282. PMID 30501455.
  10. Pelegrini, Patrícia B.; Lay, Fung T.; Murad, André M.; Anderson, Marilyn A.; Franco, Octavio L. (2008-05-22). "Novel insights on the mechanism of action of α-amylase inhibitors from the plant defensin family". Proteins: Structure, Function, and Bioinformatics. 73 (3): 719–729. doi:10.1002/prot.22086. ISSN 0887-3585. PMID 18498107.
  11. Franco, Octávio L.; Rigden, Daniel J.; Melo, Francislete R.; Grossi-de-Sá, Maria F. (January 2002). "Plant α-amylase inhibitors and their interaction with insect α-amylases: Structure, function and potential for crop protection". European Journal of Biochemistry. 269 (2): 397–412. doi:10.1046/j.0014-2956.2001.02656.x. PMID 11856298.
  12. Pelegrini, Patrícia B.; Franco, Octávio L. (November 2005). "Plant γ-thionins: Novel insights on the mechanism of action of a multi-functional class of defense proteins". The International Journal of Biochemistry & Cell Biology. 37 (11): 2239–2253. doi:10.1016/j.biocel.2005.06.011. ISSN 1357-2725. PMID 16084753.
  13. Poon, Ivan; Baxter, Amy A.; Lay, Fung; Mills, Grant D.; Adda, Christopher G.; Payne, Jennifer; Phan, Thanh Kha; Ryan, Gemma F.; White, Julie A.; Veneer, Prem K.; Weerden, Nicole L. van der (2014-04-01). "Phosphoinositide-mediated oligomerization of a defensin induces cell lysis". eLife. 3: e01808. doi:10.7554/ELIFE.01808. PMC 3968744. PMID 24692446.
  14. Baxter, Amy A.; Richter, Viviane; Lay, Fung T.; Poon, Ivan K. H.; Adda, Christopher G.; Veneer, Prem K.; Phan, Thanh Kha; Bleackley, Mark R.; Anderson, Marilyn A.; Kvansakul, Marc; Hulett, Mark D. (2015-03-23). "The Tomato Defensin TPP3 Binds Phosphatidylinositol (4,5)-Bisphosphate via a Conserved Dimeric Cationic Grip Conformation To Mediate Cell Lysis". Molecular and Cellular Biology. 35 (11): 1964–1978. doi:10.1128/mcb.00282-15. ISSN 0270-7306. PMID 25802281. S2CID 26373331.
  15. 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. doi:10.1021/bi00053a041. PMID 8380707.
  16. Janssen, Bert J. C.; Schirra, Horst Joachim; Lay, Fung T.; Anderson, Marilyn A.; Craik, David J. (2003). "Structure of Petunia hybrida Defensin 1, a Novel Plant Defensin with Five Disulfide Bonds". Biochemistry. 42 (27): 8214–8222. doi:10.1021/bi034379o. ISSN 0006-2960. PMID 12846570.
  17. Dash, Thomas S.; Shafee, Thomas; Harvey, Peta J.; Zhang, Chuchu; Peigneur, Steve; Deuis, Jennifer; Vetter, Irina; Tytgat, Jan; Anderson, Marilyn A.; Craik, David J.; Durek, Thomas (2018-12-13). "A Centipede Toxin Family Defines an Ancient Class of CSαβ Defensins". Structure. 27 (2): 315–326.e7. doi:10.1016/J.STR.2018.10.022. PMID 30554841.
  18. Shafee, Thomas M. A.; Lay, Fung T.; Hulett, Mark D.; Anderson, Marilyn A. (September 2016). "The Defensins Consist of Two Independent, Convergent Protein Superfamilies". Molecular Biology and Evolution. 33 (9): 2345–2356. doi:10.1093/molbev/msw106. ISSN 0737-4038. PMID 27297472.
  19. Shafee, Thomas M. A.; Lay, Fung T.; Phan, Thanh Kha; Anderson, Marilyn A.; Hulett, Mark D. (February 2017). "Convergent evolution of defensin sequence, structure and function". Cellular and Molecular Life Sciences. 74 (4): 663–682. doi:10.1007/s00018-016-2344-5. ISSN 1420-682X. PMID 27557668. S2CID 24741736.
  20. 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. doi:10.1007/BF00272349. PMID 1495489. S2CID 32002467.
  21. 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. doi:10.1016/0014-5793(93)81299-F. PMID 8422949. S2CID 28420512.
  22. 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. doi:10.1016/0014-5793(91)80261-Z. PMID 1995329. S2CID 84023901.
  23. 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. doi:10.1007/BF00017724. PMID 2103443. S2CID 13588960.
  24. 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. doi:10.1104/pp.101.2.699. PMC 160625. PMID 8278516.
  25. Hammami R, Ben Hamida J, Vergoten G, Fliss I (2008). "PhytAMP: a database dadicated to plant antimicrobial peptides". Nucleic Acids Research. 37 (Database issue): D963-8. doi:10.1093/nar/gkn655. PMC 2686510. PMID 18836196.

Subfamilies
This article incorporates text from the public domain Pfam and InterPro: IPR008176
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