Arthropod defensin

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Arthropod defensin
PDB 1ica EBI.jpg
Structure of insect defensin A.[1]
OPM superfamily58
OPM protein1l4v

Arthropod defensins are a family of insect and scorpion cysteine-rich antibacterial peptides, primarily active against Gram-positive bacteria.[2][3][4][5][6] All these peptides range in length from 38 to 51 amino acids. There are six conserved cysteines all involved in intrachain disulfide bonds. The role of these highly conserved cysteines is not known. Studies have shown that disulfide bonds are not required for antimicrobial activity.[7] Mammalian defensins also do not require disulfide bonds to exhibit antimicrobial activity.[8] Furthermore, it was also shown that the N-terminal helix region in arthropod or insect defensins is also not required for antimicrobial activity of these peptides.[7]

A schematic representation of peptides from the arthropod defensin family is shown below.

           |                            |
                          |   |               | |
                          +---|---------------+ |

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

Although low level sequence similarities have been reported[2] between the arthropod defensins and mammalian defensins, the topological arrangement of the disulfide bonds as well as the tertiary structure[9] are completely different in the two families.


  1. ^ Cornet B, Bonmatin JM, Hetru C, Hoffmann JA, Ptak M, Vovelle F (May 1995). "Refined three-dimensional solution structure of insect defensin A". Structure. 3 (5): 435–48. doi:10.1016/S0969-2126(01)00177-0. PMID 7663941.
  2. ^ a b Dunbar B, Lambert J, Keppi E, Wicker C, Lepage P, Hoffmann J, Fothergill J, Dimarcq JL, Reichhart JM, Van Dorsselaer A (1989). "Insect immunity: isolation from immune blood of the dipteran Phormia terranovae of two insect antibacterial peptides with sequence homology to rabbit lung macrophage bactericidal peptides". Proc. Natl. Acad. Sci. U.S.A. 86 (1): 262–266. doi:10.1073/pnas.86.1.262. PMC 286444. PMID 2911573.
  3. ^ Kobayashi K, Fujiwara S, Imai J, Fujiwara M, Yaeshima T, Kawashima T (1990). "A potent antibacterial protein in royal jelly. Purification and determination of the primary structure of royalisin". J. Biol. Chem. 265 (19): 11333–11337. PMID 2358464.
  4. ^ Yamada K, Natori S (1993). "Purification, sequence and antibacterial activity of two novel sapecin homologues from Sarcophaga embryonic cells: similarity of sapecin B to charybdotoxin". Biochem. J. 291: 275–279. PMC 1132513. PMID 8471044.
  5. ^ Cociancich S, Bulet P, Hoffmann JA, Hetru C, Lambert J, Hoffmann D, Dimarcq JL, Reichhart JM (1991). "Insect immunity. Isolation from a coleopteran insect of a novel inducible antibacterial peptide and of new members of the insect defensin family". J. Biol. Chem. 266 (36): 24520–24525. PMID 1761552.
  6. ^ Cociancich S, Bulet P, Hoffmann JA, Hegy G, Hetru C, Reuland M, Sauber F, Bischoff R, Van Dorsselaer A (1992). "A novel insect defensin mediates the inducible antibacterial activity in larvae of the dragonfly Aeschna cyanea (Paleoptera, Odonata)". Eur. J. Biochem. 209 (3): 977–984. doi:10.1111/j.1432-1033.1992.tb17371.x. PMID 1425705.
  7. ^ a b Jobin Varkey; Shashi Singh; Ramakrishnan Nagaraj (2006-06-27). "Antibacterial activity of linear peptides spanning the carboxy-terminal β-sheet domain of arthropod defensins". Peptides. 27 (11): 2614–2623. doi:10.1016/j.peptides.2006.06.010. PMID 16914230.
  8. ^ Jobin Varkey; Ramakrishnan Nagaraj (2005-08-15). "Antibacterial Activity of Human Neutrophil Defensin HNP-1 Analogs without Cysteines". Antimicrob. Agents Chemother. 49 (11): 4561–4566. doi:10.1128/AAC.49.11.4561-4566.2005. PMC 1280114. PMID 16251296.
  9. ^ Natori S, Kohda D, Hanzawa H, Shimada I, Kuzuhara T, Komano H, Inagaki F, Arata Y (1990). "1H nuclear magnetic resonance study of the solution conformation of an antibacterial protein, sapecin". FEBS Lett. 269 (2): 413–420. doi:10.1016/0014-5793(90)81206-4. PMID 2401368.

Further reading[edit]

  • Cornet B, Bonmatin JM, Hetru C, Hoffmann JA, Ptak M, Vovelle F (May 1995). "Refined three-dimensional solution structure of insect defensin A". Structure. 3 (5): 435–48. doi:10.1016/S0969-2126(01)00177-0. PMID 7663941.