Involved in the biosynthesis of decaprenylphosphoryl arabinose (DPA) a precursor for arabinan synthesis in mycobacterial cell wall biosynthesis. Catalyzes the transfer of a 5-phosphoribosyl residue from phosphoribose diphosphate (pRpp) to decaprenyl phosphate (DP) to form decaprenylphosphoryl-5-phosphoribose (DPPR). 5-phospho-alpha-D-ribose 1-diphosphate + H(+) + trans,octa-cis-decaprenyl phosphate = diphosphate + trans,octa-cis-decaprenylphospho-beta-D-ribofuranose 5-phosphate Divalent metal cations such as Mg(2+), Mn(2+) or Ca(2+). Cell wall biogenesis; cell wall polysaccharide biosynthesis. Belongs to the UbiA prenyltransferase family.