%0 Journal Article %T Trimeric Form of Intracellular ATP Synthase Subunit ¦Â of Aggregatibacter actinomycetemcomitans Binds Human Interleukin-1¦Â %A Annamari Paino %A Heidi Tuominen %A Mari J£¿£¿skel£¿inen %A Jonna Alanko %A Jari Nuutila %A Sirkka E. Asikainen %A Lauri J. Pelliniemi %A Marja T. P£¿ll£¿nen %A Casey Chen %A Riikka Ihalin %J PLOS ONE %D 2012 %I Public Library of Science (PLoS) %R 10.1371/journal.pone.0018929 %X Bacterial biofilms resist host defenses and antibiotics partly because of their decreased metabolism. Some bacteria use proinflammatory cytokines, such as interleukin (IL)-1¦Â, as cues to promote biofilm formation and to alter virulence. Although one potential bacterial IL-1¦Â receptor has been identified, current knowledge of the bacterial IL-1¦Â sensing mechanism is limited. In chronic biofilm infection, periodontitis, Aggregatibacter actinomycetemcomitans requires tight adherence (tad)-locus to form biofilms, and tissue destroying active lesions contain more IL-1¦Â than inactive ones. The effect of IL-1¦Â on the metabolic activity of A. actinomycetemcomitans biofilm was tested using alamarBlue£¿. The binding of IL-1¦Â to A. actinomycetemcomitans cells was investigated using transmission electron microscopy and flow cytometry. To identify the proteins which interacted with IL-1¦Â, different protein fractions from A. actinomycetemcomitans were run in native-PAGE and blotted using biotinylated IL-1¦Â and avidin-HRP, and identified using mass spectroscopy. We show that although IL-1¦Â slightly increases the biofilm formation of A. actinomycetemcomitans, it reduces the metabolic activity of the biofilm. A similar reduction was observed with all tad-locus mutants except the secretin mutant, although all tested mutant strains as well as wild type strains bound IL-1¦Â. Our results suggest that IL-1¦Â might be transported into the A. actinomycetemcomitans cells, and the trimeric form of intracellular ATP synthase subunit ¦Â interacted with IL-1¦Â, possibly explaining the decreased metabolic activity. Because ATP synthase is highly conserved, it might universally enhance biofilm resistance to host defense by binding IL-1¦Â during inflammation. %U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018929