L-arabinose-binding periplasmic protein (ABP)

The L-arabinose-binding periplasmic protein (commonly abbreviated as ABP or known as the AraF protein in *Escherichia coli*) is a periplasmic substrate-binding protein essential for the high-affinity uptake of L-arabinose in Gram-negative bacteria, such as *E. coli*[1][7][10]. It is part of the ATP-binding cassette (ABC) transporter apparatus specific for L-arabinose import; this system enables bacteria to utilize arabinose as a carbon source, especially under low nutrient conditions[1][7][9]. ABP binds L-arabinose with high affinity and can also interact, though more weakly, with related sugars such as D-galactose and D-fucose[1][9][6]. Structurally, the protein is located in the periplasmic space—between the inner and outer membranes in Gram-negative bacteria[7][10]. Crystal structures reveal it possesses a bilobal (two-lobe) fold with a sugar-binding cleft in between, which accommodates both the alpha- and beta-anomers of L-arabinose[6][2][5]. ABP is not considered a human therapeutic target, has no direct disease role, and is not relevant for drug targeting, biomarker use, or therapeutic safety in a clinical context[3][10].

Other names

AraF proteinarabinose-binding proteinABP