Rise of Bacterial Small Proteins and Peptides in Therapeutic Applications

Background: Polypeptides that comprise less than 100 amino acids (50 amino acids in some cases) are referred to as small proteins (SPs), however, as of date, there is no strict definition. In contrast to the small polypeptides that arise due to proteolytic activity or abrupt protein synthesis, SPs are coded by small open reading frames (sORFs) and are conventionally synthesized by ribosomes. Purpose of the Review: Although proteins that contain more than 100 amino acids have been studied exquisitely, studies on small proteins have been largely ignored, basically due to the unsuccessful detection of these SPs by traditional methodologies/techniques. Serendipitous observation of several small proteins and elucidation of their vital functions in cellular processes opened the floodgate of a new area of research on the new family of proteins called "Small proteins". Having known the significance of such SPs, several advanced techniques are being developed to precisely identify and characterize them. Conclusion: Bacterial small proteins (BSPs) are being intensely investigated in recent days and that has brought the versatile role of BSPs into the limelight. In particular, identification of the fact that BSPs exhibit antimicrobial activity has further expanded its scope in the area of therapeutics. Since the microbiome plays an inevitable role in determining the outcome of personalized medicine, studies on the secretory small proteins of the microbiome are gaining momentum. This review discusses the importance of bacterial small proteins and peptides in terms of their therapeutic applications.