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
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary

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

The modes of action of different defensins depends on the type of fungus they are interacting with. Most characterized 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. S2CID 3543741.
  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. S2CID 28378146.
  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. PMC 4420927. 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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