Obtaining, identification, and structural characterization of bioactive peptides from different microbial sources
Project no. 24139 · Status: Kapanmış (Yayın bekleniyor) · 2022
Summary
<p>Bioactive peptides (BAPs) are short polypeptides that possess biological activity on living organisms and generally have positive effects on health. Studies on BAPs have been focused in the fields of health and food research. Research focused on identifying new BAPs with antihypertensive, antidiabetic, and antioxidant activities is important for health. The potential use of BAPs as natural alternatives to drugs which often have side effects used in the treatment of obesity, hypertension, and cardiovascular diseases, is noteworthy. The identification of new BAPs with antibacterial and antioxidant activities is important for ensuring food safety through natural components. Furthermore, the identification of new BAPs with antibacterial activity is a critical subject of focus for combating antibiotic-resistant bacteria.</p><p></p><p>The main objective of the project is to identify new BAP candidates, purify them by producing them using natural or recombinant methods, and also to elucidate the peptides' mechanisms of activity at the atomic level through structural analyses. The first unique value of the project is the identification and detailed characterization of new BAP candidates from lactic acid bacteria. Another unique value is the development of a method for producing peptides that are difficult to obtain from natural sources but have high activity. Finally, within the project flow, resolving the structures of the selected peptides and elucidating their interactions with the target molecule is also one of the unique values.</p><p></p><p>Microbial fermentation with new isolates and peptide purification from the supernatants is an approach used in recent years for the identification of new BAP candidates. In the proposed project, the BAP-derived antibacterial and antioxidant properties of local lactic acid bacteria (LAB) isolates, which were previously isolated from various foods in our earlier studies, will be screened. The strains exhibiting BAP-derived antibacterial effects and/or high antioxidant activity will also be examined for their Angiotensin-Converting Enzyme (ACE) and Dipeptidyl Peptidase IV (DPP-IV) enzyme inhibition activities. Following the analyses, the LAB culture supernatants possessing bioactivity will undergo advanced purification procedures to obtain high-purity LAB-derived peptide fractions, and their amino acid sequences will be determined. In the proposed project, recombinant peptide production will also be carried out to develop an approach for the recombinant production of BAPs—whose activities are predicted in bioinformatics BAP databases, but which are difficult to obtain in pure and sufficient quantities from natural sources.</p><p></p><p>Antimicrobial, ACE inhibitor, and DPP-IV inhibitor peptide sequences found in databases and literature will be produced and purified in the Escherichia coli recombinant system with a SUMO fusion partner. Furthermore, in cases where the yields of selected LAB-derived peptides with high bioactivity are low, they will also be produced recombinantly. The project will also integrate experimental and computational structural biology approaches to elucidate the working mechanisms of the peptides at an atomistic level. The secondary structures of the purified peptides will be checked using circular dichroism, and macromolecular crystallography, nuclear magnetic resonance spectroscopy, and small-angle X-ray scattering techniques will be employed to resolve the experimental structures of the peptides found to have a defined structure. The structures of peptides whose experimental structures cannot be solved will be calculated using the AlphaFold source code. The interactions of the peptide structures obtained in this way with the target molecules will be examined at the atomic level using docking analyses.</p><p></p><p></p><p>The proposed project is structured with a multidisciplinary approach encompassing the fields of microbiology, biochemistry, and structural biology. Consequently, the project team includes researchers who are experts in these fields. The Principal Investigator has work in the areas of protein engineering, biochemistry, and structural biology and has experience in the field of bioactive peptides through a TÜBİTAK-supported project (117O319) that was successfully completed. The doctoral student who served as a scholarship holder in that same project will serve as a scholarship holder in the proposed project under the guidance of the Principal Investigator. Prof. Dr. Duygu Kışla, who has research on LAB isolation and identification for microbiology studies, will serve as a researcher. Dr. Çağdaş Dağ will serve as a consultant for the project with their expertise in experimental structural biology, and Dr. Ezgi Karaca will consult with their expertise in computational structural biology.</p><p></p><p>In summary, the proposed project plans to: identify new BAP sequences; establish a recombinant BAP production system; and perform integrated structural characterization of the purified peptides. The successful completion of the project will yield new peptide sequences and structures. These outputs will provide a very strong starting point for specialized studies on the use of peptides in both the food and health sectors. Furthermore, a contribution will be made to the advancement and development of structural biology studies, which are still developing in our country.</p>