1.C.66 The Puroindoline (Puroindoline) Family

Plant seeds contain high concentrations of antimicrobial peptides and proteins that confer disease resistance. Puroindolines a and b (about 13 kDa; a is of 148 aas), wheat endosperm-specific proteins with N-terminal hydrophobic segments and tryptophan-rich hydrophobic domains, have antimicrobial activities. A 13 aa residue fragment from puroindoline a, called PuroA (FPVTWRWWKWWKG-NH₂) exhibits activity against Gram-positive and Gram-negative bacteria as well as fungi. The intact protein and the peptide interact with membranes due to their ability to bind polar lipids with high affinity. The peptide interacts primarily with anionic phospholipids and induces dye release from vesicles, suggesting that it induces channel formation (Jing et al., 2003). They may form transient toroidal pores comprised of both peptide and lipid. It is not clear how stable these pores are or what this pore size is (H. Vogel, personal communication). Multiple homologues of puroindolines are found in many plants.

The transport reaction catalyzed by PuroA and presumably by puroindoline is:

small molecules (in) small molecules (out)