Selection of Peptidoglycan-Specific Aptamers for Bacterial Cells Identification

• Published in: Applied biochemistry and biotechnology 2014-12, Vol.174 (7), p.2548-2556
• Main Authors: Ferreira, Iêda Mendes, de Souza Lacerda, Camila Maria, de Faria, Lígia Santana, Corrêa, Cristiane Rodrigues, de Andrade, Antero Silva Ribeiro
• Format: Article
• Language: English
• Subjects: Aptamers, Nucleotide - chemistry; Bacteria; Bacterial diseases; bacterial infections; Biochemistry; Biological and medical sciences; Biotechnology; Candida albicans; Candida albicans - chemistry; cell walls; Cells; Chemistry; Chemistry and Materials Science; crosslinking; dissociation; E coli; Escherichia coli; Escherichia coli - chemistry; evolution; fibroblasts; Fundamental and applied biological sciences. Psychology; Humans; image analysis; Molecules; oligonucleotides; Peptides; Peptidoglycan - analysis; Peptidoglycan - chemistry; peptidoglycans; radionuclides; RNA; single-stranded DNA; Staphylococcus aureus; Staphylococcus aureus - chemistry
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-014-1206-6

Peptidoglycan is a highly complex and essential macromolecule of bacterial outer cell wall; it is a heteropolymer made up of linear glycan strands cross-linked by peptides. Peptidoglycan has a particular composition which makes it a possible target for specific bacterial recognition. Aptamers are single-stranded DNA or RNA oligonucleotides that bind to target molecules with high affinity and specificity. Aptamers can be labeled with different radioisotopes and possess several properties that make them suitable for molecular imaging. The purpose of this study was to obtain aptamers for use as radiopharmaceutical in bacterial infection diagnosis. Two aptamers (Antibac1 and Antibac2) against peptidoglycan were selected through the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) methodology. The dissociation constant (Kd) for Antibac1 was 0.415 + 0.047 μM and for Antibac2 was 1.261 + 0.280 μM. These aptamers labeled with³²P showed high affinity for Staphylococcus aureus cells. The binding to S. aureus and Escherichia coli in vitro were significantly higher than for Candida albicans and human fibroblasts, demonstrating their specificity for bacterial cells. These results point Antibac1 and Antibac2 as promising tools for bacterial infections identification.