English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Bacterial ABC importers catalyze the uptake of essential nutrients including transition metals and metal-containing co-factors. Recently, an IgG antibody targeting the external binding protein of the  Staphylococcus aureus  Mn(II) ABC importer was reported to inhibit transport activity and reduce bacterial cell growth. We here explored the possibility of using alpaca-derived nanobodies to inhibit the vitamin B12 transporter of  Escherichia coli , BtuCD-F, as a model system by generating nanobodies against the periplasmic binding protein BtuF. We isolated six nanobodies that competed with B12 for binding to BtuF, with inhibition constants between 10 −6  and 10 −9  M. Kinetic characterization of the nanobody-BtuF interactions revealed dissociation half-lives between 1.6 and 6 minutes and fast association rates between 10 4  and 10 6  M −1 s −1 . For the tightest-binding nanobody, we observed a reduction of  in vitro  transport activity of BtuCD-F when an excess of nanobody over B12 was used. The structure of BtuF in complex with the most effective nanobody Nb9 revealed the molecular basis of its inhibitory function. The CDR3 loop of Nb9 reached into the substrate-binding pocket of BtuF, preventing both B12 binding and BtuCD-F complex formation. Our results suggest that nanobodies can mediate ABC importer inhibition, providing an opportunity for novel antibiotic strategies.

Structural basis of nanobody-mediated blocking of BtuF, the cognate substrate-binding protein of the Escherichia coli vitamin B12 transporter BtuCD