title: Probing protein sequences as sources for encrypted antimicrobial peptides.
abstract: Starting from the premise that a wealth of potentially biologically active peptides may lurk within proteins, we describe here a methodology to identify putative antimicrobial peptides encrypted in protein sequences. Candidate peptides were identified using a new screening procedure based on physicochemical criteria to reveal matching peptides within protein databases. Fifteen such peptides, along with a range of natural antimicrobial peptides, were examined using DSC and CD to characterize their interaction with phospholipid membranes. Principal component analysis of DSC data shows that the investigated peptides group according to their effects on the main phase transition of phospholipid vesicles, and that these effects correlate both to antimicrobial activity and to the changes in peptide secondary structure. Consequently, we have been able to identify novel antimicrobial peptides from larger proteins not hitherto associated with such activity, mimicking endogenous and/or exogenous microorganism enzymatic processing of parent proteins to smaller bioactive molecules. A biotechnological application for this methodology is explored. Soybean (Glycine max) plants, transformed to include a putative antimicrobial protein fragment encoded in its own genome were tested for tolerance against Phakopsora pachyrhizi, the causative agent of the Asian soybean rust. This procedure may represent an inventive alternative to the transgenic technology, since the genetic material to be used belongs to the host organism and not to exogenous sources.
authors.affiliation: Laboratório de Espectrometria de Massa, Embrapa Recursos Genéticos e Biotecnologia, Brasília, Distrito Federal, Brazil.
authors.forename: Guilherme D
authors.initials: GD
authors.lastname: Brand
authors.forename: Mariana T Q
authors.initials: MT
authors.lastname: Magalhães
authors.forename: Maria L P
authors.initials: ML
authors.lastname: Tinoco
authors.forename: Francisco J L
authors.initials: FJ
authors.lastname: Aragão
authors.forename: Jacques
authors.initials: J
authors.lastname: Nicoli
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Kelly
authors.forename: Alan
authors.initials: A
authors.lastname: Cooper
authors.forename: Carlos
authors.initials: C
authors.lastname: Bloch
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D001487:Basidiomycota / Q000187:drug effects; D002152:Calorimetry, Differential Scanning; D004926:Escherichia coli / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D025341:Principal Component Analysis; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D020539:Sequence Analysis, Protein; D013025:Glycine max / Q000235:genetics / Q000382:microbiology; D013172:Spores, Fungal / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D010446:Peptide Fragments; D010940:Plant Proteins