title: Small cationic protein from a marine turtle has beta-defensin-like fold and antibacterial and antiviral activity.
abstract: Egg white of marine turtle Caretta caretta contains a small cationic protein but lacks lysozyme. The protein was sequenced by a combination of sequential Edman degradation, carboxypeptidase digestion, nuclear magnetic resonance (NMR) and electrospray ionization tandem mass spectrometry. The protein contains 36 amino acid residues of which six are half-cysteines. The three-dimensional structure of the protein was deduced from two-dimensional NMR experiments and was observed to be similar to vertebrate beta-defensins. However, disulfide connectivity is C1-C6/C2-C5/C3-C4; different from that of the vertebrate beta-defensins. The protein showed strong antibacterial activity against Escherichia coli and Salmonella typhimurium. The protein also showed significant antiviral activity against an enveloped rhabdovirus, Chandipura virus, which is an emerging human pathogen. This virus is also closely related to the vesicular stomatitis virus, whose growth was also inhibited. This small cationic protein is part of the innate immunity of this organism and replaces lysozyme in the egg. It has the potential to be developed as an antibacterial and antiviral agent.
authors.affiliation: Department of Biophysics, Bose Institute, Calcutta, India.
authors.forename: Suranjana
authors.initials: S
authors.lastname: Chattopadhyay
authors.forename: Nirmal Kumar
authors.initials: NK
authors.lastname: Sinha
authors.forename: Shuvojit
authors.initials: S
authors.lastname: Banerjee
authors.forename: Debjani
authors.initials: D
authors.lastname: Roy
authors.forename: Dhrubajyoti
authors.initials: D
authors.lastname: Chattopadhyay
authors.forename: Siddhartha
authors.initials: S
authors.lastname: Roy
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology; D002412:Cations; D003545:Cysteine / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011487:Protein Conformation; D012486:Salmonella typhimurium / Q000378:metabolism; D014426:Turtles; D018116:Vesiculovirus / Q000378:metabolism; D023083:beta-Defensins / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D000998:Antiviral Agents; D002412:Cations; D023083:beta-Defensins; D003545:Cysteine