Anti-biofilm and sporicidal activity of peptides based on wheat puroindoline and barley hordoindoline proteins.

The broad-spectrum activity of antimicrobial peptides (AMPs) and low probability of development of host resistance make them excellent candidates as novel bio-control agents. A number of AMPs are found to be cationic, and a small proportion of these are tryptophan-rich. The puroindolines (PIN) are small, basic proteins found in wheat grains with proposed roles in biotic defence of seeds and seedlings.

The antimicrobial domains of wheat puroindolines are cell-penetrating peptides with possible intracellular mechanisms of action.

The puroindoline proteins (PINA and PINB) of wheat display lipid-binding properties which affect the grain texture, a critical parameter for wheat quality. Interestingly, the same proteins also display antibacterial and antifungal properties, attributed mainly to their Tryptophan-rich domain (TRD). Synthetic peptides based on this domain also display selectivity towards bacterial and fungal cells and do not cause haemolysis of mammalian cells.

Stability of puroindoline peptides and effects on wheat rust.

Peptides modelled on the tryptophan rich domain of puroindolines and the related grain softness protein-1 have a broad range of antibacterial and antifungal activities. With the aims of further investigating the activities of these antimicrobial peptides we studied their activity against wheat rust diseases and environmental stability. PINA-based peptides were found to have high pH and thermal stability in addition to being stable over long periods at room temperature.