title: Identification and functional characterization of an uncharacterized antimicrobial peptide from a ciliate Paramecium caudatum.
abstract: The global ever-growing concerns about multi-drug resistant (MDR) microbes leads to urgent demands for exploration of new antibiotics including antimicrobial peptides (AMPs). Here we demonstrated that a cDNA from Ciliata Paramecium caudatum, designated Pcamp1, coded for a protein with features characteristic of AMPs, which is not homologous to any AMPs currently known. Both the C-terminal 91 amino acid residues of PcAMP1, cPcAMP1, expressed in Escherichia coli and the C-terminal 26 amino acid residues (predicted mature AMP), cPcAMP1/26, synthesized, underwent a coil-to-helix transition in the presence of TFE, SDS or DPC. Functional assays revealed that cPcAMP1 and cPcAMP1/26 were both able to kill Aeromonas hydrophila and Staphylococcus aureus. ELISA showed that cPcAMP1 and cPcAMP1/26 were able to bind to microbe-associated molecular pattern molecules LPS and LTA, which was further corroborated by the observations that cPcAMP1 could deposit onto the bacterial membranes. Importantly, both cPcAMP1 and cPcAMP1/26 were able to induce bacterial membrane permeabilization and depolarization, and to increase intracellular ROS levels. Additionally, cPcAMP1 and cPcAMP1/26 were not cytotoxic to mammalian cells. Taken together, our results show that PcAMP1 is a potential AMP with a membrane selectivity towards bacterial cells, which renders it a promising template for the design of novel peptide antibiotics against MDR microbes. It also shows that use of signal conserved sequence of AMPs can be an effective tool to identify potential AMPs across different animal classes.
authors.affiliation: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao, 266003, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Cui
authors.affiliation: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao, 266003, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao, 266003, China.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Li
authors.affiliation: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao, 266003, China.
authors.forename: Yubo
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, China. Electronic address: sczhang@ouc.edu.cn.
authors.forename: Shicui
authors.initials: S
authors.lastname: Zhang
mesh_terms: D016980:Aeromonas hydrophila / Q000187:drug effects / Q000378:metabolism; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects; D015870:Gene Expression; D006461:Hemolysis; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008564:Membrane Potentials; D048488:Paramecium caudatum / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D017433:Protein Structure, Secondary; D017382:Reactive Oxygen Species / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species
keywords: Antibiotics; Antimicrobial peptides; Ciliate; Multi-drug resistant microbes; Paramecium