Molecular Characterization and Gene Expression Profiling ... - CUSAT

Chapter 2
by degranulation into the blood upon immune response stimulation (Bachere
et al., 2000a). The distribution of penaeidin transcripts and proteins is
restricted to haemocytes that are present strikingly in almost all the shrimp
tissues, both circulating in blood vessels irrigating the tissues or infiltrating
tissues such as the brain, subcuticular epithelia, midgut cecum, or muscle.
2.1.3.6. Effect of post-translational modifications on bioactivity
of penaeidins
Post-translational modifications were found to have little effect on
penaeidin antimicrobial properties (Destoumieux et al., 1999), but possibly
they increase the stability of penaeidins, which are highly resistant to
proteolysis (Destoumieux et al., 1997). N-terminal blocking has no effect on
penaeidin antimicrobial properties (Destoumieux et al., 2000a). Moreover,
when C-terminal amidation is replaced by an extra glycine residue,
penaeidin antifungal properties are unaltered, and antibacterial activity is
decreased only two-fold. The partial loss of antibacterial activity that occurs
in non-amidated penaeidins may be due to the loss of a positive charge at the
C-terminus, and consequently to less efficient interaction of the peptide with
bacterial membranes. Until now in shrimp, only penaeidins, a family of
antimicrobial peptides, have been intensively studied in terms of biological
properties, antimicrobial activities, gene expression and localization in
response to infection (Bachere et al., 2004). The other antimicrobial effectors
recently identified such as crustins or ALFs remain to be characterized for
their biological properties and immune functions.
Molecular Characterization and Gene Expression Profiling of Antimicrobial Peptides in Penaeid Shrimps
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