Identification of a novel storage glycine-rich peptide from guava ( Psidium guajava) seeds with activity against Gram-negative bacteria

• Published in: Peptides (New York, N.Y. : 1980) Vol. 29; no. 8; pp. 1271 - 1279
• Main Authors: Pelegrini, Patricia B., Murad, André M., Silva, Luciano P., dos Santos, Rachel C.P., Costa, Fabio T., Tagliari, Paula D., Bloch Jr, Carlos, Noronha, Eliane F., Miller, Robert N.G., Franco, Octavio L.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-08-2008; Elsevier Science
• Subjects: Amino Acid Sequence; Anti-Infective Agents - chemistry; Anti-Infective Agents - isolation & purification; Anti-Infective Agents - pharmacology; Antimicrobial peptides; Biological and medical sciences; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Glycine - chemistry; Glycine-rich proteins; Gram-Negative Bacteria - drug effects; Microbial Sensitivity Tests; Models, Molecular; Molecular Sequence Data; Plant Proteins - chemistry; Plant Proteins - isolation & purification; Plant Proteins - pharmacology; Protein Conformation; Psidium - chemistry; Psidium guajava; Seeds - chemistry; Sequence Alignment; Toxin; Vertebrates: endocrinology; BtuB; GRP; MALDI-ToF; Glycine-rich proteins; MIC; MS; LTP; Pg-AMP1; HCl; SDS-PAGE; Toxin; ESI-Q-ToF; Tu-AMP1; DDR; Psidium guajava; LB; Antimicrobial peptides; RIP; GlcNAc; Pp-TH; HPLC; Peptides; Glycine; Antimicrobial agent; Protein; Storage; Aminoacid; Neurotransmitter; Bacteria; Antibacterial agent
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/j.peptides.2008.03.013

Bacterial pathogens cause an expressive negative impact worldwide on human health, with ever increasing treatment costs. A significant rise in resistance to commercial antibiotics has been observed in pathogenic bacteria responsible for urinary and gastro-intestinal infections. Towards the development of novel approaches to control such common infections, a number of defense peptides with antibacterial activities have been characterized. In this report, the peptide
Pg-AMP1 was isolated from guava seeds (
Psidium guajava) and purified using a Red-Sepharose Cl-6B affinity column followed by a reversed-phase HPLC (Vydac C18-TP).
Pg-AMP1 showed no inhibitory activity against fungi, but resulted in a clear growth reduction in
Klebsiella sp. and
Proteus sp., which are the principal pathogens involved in urinary and gastro-intestinal hospital infections. SDS-PAGE and mass spectrometry (MALDI-ToF) characterized
Pg-AMP1 a monomer with a molecular mass of 6029.34
Da and small quantities of a homodimer. Amino acid sequencing revealed clear identity to the plant glycine-rich protein family, with
Pg-AMP1 the first such protein with activity towards Gram-negative bacteria. Furthermore,
Pg-AMP1 showed a 3D structural homology to an enterotoxin from
Escherichia coli, and other antibacterial proteins, revealing that it might act by formation of a dimer.
Pg-AMP1 shows potential, in a near future, to contribute to development of novel antibiotics from natural sources.