L-arabinose-binding periplasmic protein (AraF) (AraF)

L-arabinose-binding protein AraF (also known as ABP) is a periplasmic substrate-binding protein found in Gram-negative bacteria, most notably Escherichia coli. It serves as the primary receptor for L-arabinose in the high-affinity AraFGH ATP-binding cassette (ABC) transport system, facilitating the uptake of this pentose sugar for catabolism (UniProt P02924). AraF binds L-arabinose with high specificity and affinity, undergoing a Venus flytrap conformational change to deliver the ligand to the membrane-bound permease complex (AraGH) (RCSB PDB 1ABE). While primarily a metabolic protein, AraF is a subject of interest in the development of targeted antimicrobial therapies, such as sugar-drug conjugates that exploit bacterial transport systems for selective drug entry (Preprints.org 2026). It is also a model system for studying protein-carbohydrate interactions and the regulation of bacterial transport under oxidative stress, where its function is modulated by the redox state of its cysteine residues (J. Biol. Chem. 2014). This protein should not be confused with the human A-Raf proto-oncogene (ARAF), which is a serine/threonine kinase involved in the MAPK/ERK signaling pathway and a target in oncology (GeneCards).

Other names

ABPL-arabinose-binding proteinArabinose-binding proteinABC transporter L-arabinose-binding periplasmic protein

Substrate binding and delivery to the AraGH permease complex of the ABC transporter system