Inhibitory effect of puroindoline peptides on Campylobacter jejuni growth and biofilm formation.

Authors: TALUKDAR, PRABHAT - Washington State University; TURNER, KYRAH - Washington State University; LU, XIAONAN - University Of British Columbia; Morris, Craig; KONKEL, MICHAEL - Washington State University

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2021
Publication Date: 7/2/2021
Citation: Talukdar, P.K., Turner, K.L., Lu, X., Morris, C.F., Konkel, M.E. 2021. Inhibitory effect of puroindoline peptides on Campylobacter jejuni growth and biofilm formation.. Frontiers in Microbiology. 12. Article 702762. https://doi.org/10.3389/fmicb.2021.702762.
DOI: https://doi.org/10.3389/fmicb.2021.702762

Interpretive Summary: Microorganisms, including commensals and pathogens, have developed antimicrobial resistance to existing drugs, and therefore, the development of alternative therapies is warranted to combat the emergence and spread of multi-drug resistant bacteria. Antimicrobial peptides (AMPs) from natural sources such as plants, insects, and other living animals are thought to be potential alternatives to conventional antibiotics due to their broad-spectrum antimicrobial activities and low potential for development of diseases. The search for new AMPs from natural sources as well as acquiring information on the antimicrobial activities of already known AMPs against a wider range of organisms is crucial to finding suitable natural alternatives to existing drugs. Our study further strengthens the fact that PinA is an effective antimicrobial agent against many bacteria including the foodborne pathogen C. jejuni. The use of PinA with other antimicrobial agents or natural products could be used as potential therapeutic agents against bacterial infection. Puroindolines are located in the endosperm of wheat and are present in the end-products of wheat such as flour or bread. Additionally, puroindoines are members of a larger familiy of ‘indolines’ which are present in oat, barley, rye and other commonly consumed cereals.

Technical Abstract: Puroindolines are small, amphipathic, wheat proteins that determine the hardness of the wheat kernel and protect crops from different pathogens. Puroindoline A (PinA) and puroindoline B (PinB) are two major isoforms of puroindolines that possess characteristic tryptophan-rich domains (TRD) and have antimicrobial properties. Although the antibacterial and antifungal properties of PinA and PinB have been shown previously for some organisms, the wide-spectrum of antimicrobial activity of these two proteins has yet to be known. In this study, we used standard biophysical assays to investigate the antimicrobial effect of PinA and PinB synthetic peptides against Campylobacter jejuni growth and biofilm formation. C. jejuni is an important microaerobic, foodborne pathogen that causes gastrointestinal and neurological diseases in humans. Our results showed that: 1) PinA has strong antimicrobial activity against C. jeuni clinical strains 81-176 and F38011, Escherichia coli O157:H7, methicillin-resistant Staphylococcus aureus, Salmonella enterica subsp. enterica serovar Typhimurium, and Listeria monocytogenes; 2) The substitution of two tryptophan residues to glycine (W G) in the TRD of PinA abolishes its antimicrobial activity against these organisms; 3) PinA functions synergistically with ciprofloxacin or erythromycin to inhibit or kill C. jejuni strains; 4) PinA is cytotoxic at a concentration of 256 µg/mL or greater on mammalian INT 407 cells; and 5) PinA at high concentration (>256 µg/mL) inhibits C. jejuni biofilm formation. In summary, this study demonstrates the antimicrobial activity of PinA against C. jejuni growth and biofilm formation and further confirms the potential use of PinA as a therapeutic agent in health care or as preservatives in the food industry.