Isolation and structural characterization of a Zn2+-bound single-domain antibody against NorC, a putative multidrug efflux transporter in bacteria.
J Biol Chem
; 295(1): 55-68, 2020 01 03.
Article
em En
| MEDLINE
| ID: mdl-31699895
ABSTRACT
Single-chain antibodies from camelids have served as powerful tools ranging from diagnostics and therapeutics to crystallization chaperones meant to study protein structure and function. In this study, we isolated a single-chain antibody from an Indian dromedary camel (ICab) immunized against a bacterial 14TM helix transporter, NorC, from Staphylococcus aureus We identified this antibody in a yeast display screen built from mononuclear cells isolated from the immunized camel and purified the antibody from Escherichia coli after refolding it from inclusion bodies. The X-ray structure of the antibody at 2.15 Å resolution revealed a unique feature within its CDR3 loop, which harbors a Zn2+-binding site that substitutes for a loop-stabilizing disulfide bond. We performed mutagenesis to compromise the Zn2+-binding site and observed that this change severely hampered antibody stability and its ability to interact with the antigen. The lack of bound Zn2+ also made the CDR3 loop highly flexible, as observed in all-atom simulations. Using confocal imaging of NorC-expressing E. coli spheroplasts, we found that the ICab interacts with the extracellular surface of NorC. This suggests that the ICab could be a valuable tool for detecting methicillin-resistant S. aureus strains that express efflux transporters such as NorC in hospital and community settings.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Zinco
/
Proteínas Associadas à Resistência a Múltiplos Medicamentos
/
Anticorpos de Domínio Único
/
Anticorpos Antibacterianos
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Índia