Periplasmic L-arabinose-binding protein (ABP) is involved in the high-affinity L-arabinose membrane transport system. It binds with high affinity to arabinose, but can also bind D-galactose (at approximately 2-fold lower affinity) and D-fucose (at approximately 40-fold lower affinity) [, ].The periplasmic ABP consists of two alpha/beta globular domains connected by a three-stranded hinge, a Venus flytrap-like domain, which undergoes a transition from an open to a closed conformational state upon ligand binding. Moreover, ABP is homologous to the ligand-binding domain of eukaryotic receptors such as metabotropic glutamate receptor (mGluR) and DNA-binding transcriptional repressors such as LacI and GalR [].
Alpha-(1->3)-arabinofuranosyltransferase is involved in the biosynthesis of the arabinogalactan (AG) region of the mycolylarabinogalactan-peptidoglycan (mAGP) complex, an essential component of the mycobacterial cell wall. It catalyzes the addition of an arabinofuranosyl (Araf) residue from the sugar donor decaprenyl-phospho-arabinose (DPA) on the C-3 of an alpha-(1->5)-linked Araf from the arabinan backbone of AG [].
