Conformational changes of pediocin in an aqueous medium monitored by fourier transform infrared spectroscopy: a biological implication.
Fourier transform infrared (FTIR) spectroscopy was used to investigate the secondary structure of pediocin PA-1 in different aqueous media in relation to its antimicrobial activity. The experiments were performed at pD (pH meter corrected for deuterium isotope effect) 6, 7, and 8 and during a heating-cooling cycle of 20-80 degrees C. At pD 6, (i.e. pediocin's most active form), the FTIR results show that pediocin adopts an unordered structure with a small contribution of beta-turn. After a heating-cooling cycle, thermally-induced changes in pediocin are reversed and its activity is maintained. Increasing the pD to 7 and 8 leads to a more ordered secondary structure. For these two pD values, an increase in temperature induces an irreversible aggregation of protein as revealed by the amide I' band. The analysis of the Tyr region provides more insight into the aggregation process. In fact, it appears to be a two-step process, involving first the C (carboxy)-terminus of pediocin and then the N (amino)-terminus. This study reveals two major points: (1) the preservation of pediocin flexibility is essential for maintaining its activity; and (2) the aggregation of its C-terminus is sufficient to induce a loss of activity, suggesting that this region plays an important role in the activity of pediocin.
Gaussier
Hélène
H
Chaire de recherche du Canada sur les protéine et les ailments fonctionnels, Université Laval, département des aliments et de nutrition, Pavillon Paul Comtois, Sainte-Foy, Québec, G1K 7P4, Canada.
Lavoie
Marc
M
Subirade
Muriel
M
D000900:Anti-Bacterial Agents / Q000737:chemistry; D001430:Bacteriocins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D000070017:Pediocins; D010376:Pediococcus / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013329:Structure-Activity Relationship; D013696:Temperature; D014443:Tyrosine / Q000737:chemistry
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D000070017:Pediocins; C074288:pediocin PA-1; D014443:Tyrosine