Molecular Characterization and Gene Expression Profiling ... - CUSAT

Chapter 1
conformations adopted by these peptides in the context of the native protein
(Giansanti et al., 2005).
Lactoferricin and polyphemusin have β-structures stabilized by one
and two internal disulfide bridges, respectively. These disulfide bridges have
been shown to be crucial for the antiviral activity of the peptides (Tamamura
et al., 1994; Andersen et al., 2001; Jenssen et al., 2004b). Despite their diverse
structures, many peptides possess analogous antiviral modes of action
(Jenssen et al., 2004a, 2004b), indicating that these peptides are able to
interact with their targets, despite large structural differences. Interestingly,
although the viral target of the AMPs appears to vary, the demonstrated
antiviral effects are quite similar.
Mode of action of antiviral peptides
Blocking of viral entry by heparan sulfate interaction: Heparan sulfate
is the most important glycosaminoglycan molecule with respect to viral
attachment (Spillmann, 2001; Mettenleiter, 2002); consequently, blocking of
heparan sulfate can reduce the viral infection (WuDunn and Spear, 1989;
Shieh et al., 1992). The importance of heparan sulfate for different viral
infections varies considerably. Enzymatic removal of cellular heparan sulfate
and chondroitin sulfate has led to the observation that these proteoglycan
molecules have minor influences on HIV attachment to host cells. However,
it has been demonstrated that they are of major importance for HIV entry
and replication (Argyris et al., 2003). The large number of positively charged
residues in AMPs enable them to interact electrostatically with negatively
charged cell surface molecules, including heparan sulfate. Human α-
defensin, LL-37, and magainin have all been shown to interact with different
glycosaminoglycan molecules (James et al., 1994; Schmidtchen et al., 2001,
2002). The peptides exhibited different antiviral effects for HSV type 1 and 2,
an observation attributed to the combined effects of the amino acid content
and the structures of the peptides (Andersen et al., 2003; Jenssen et al., 2004a,
Molecular Characterization and Gene Expression Profiling of Antimicrobial Peptides in Penaeid Shrimps
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