Part of the cluster that mediates the biosynthesis of a highly modified cyclo-arginine-tryptophan dipeptide (cRW). The first step of the pathway is perfornmed by the arginine-containing cyclodipeptide synthase (RCPDS) avaA that acts as the scaffold-generating enzyme and is responsible for formation of the cyclo-Arg-Trp (cRW) diketopiperazine. AvaB then acts as a multifunctional flavoenzyme that is responsible for generating the cyclo-Arg-formylkynurenine DKP, which can be deformylated by avaC. AvaB then further catalyzes an additional N-oxidation followed by cyclization and dehydration. The next step is an N-acetylation of the guanidine group catalyzed by the arginine N-acetyltransferase avaD. The roles of the additional enzymes identified within the ava cluster still have to be determined