Involved in the biosynthesis of the proteosome inhibitor salinosporamide A (SalA). Catalyzes the halogenation of S-adenosyl-L-methionine (SAM) with chloride to generate 5'-chloro-5'-deoxyadenosine (5'-CIDA) and L-methionine. It can also use bromide and iodide, producing halogenated 5'-deoxyadenosine (5'-XDA) and L-methionine, however no halogenase activity is detected in the presence of fluoride. chloride + S-adenosyl-L-methionine = 5'-chloro-5'-deoxyadenosine + L-methionine Homotrimer. Cells lacking this gene are not able to produce salinosporamide A (SalA), however they produce salinosporamide B. Belongs to the SAM hydrolase / SAM-dependent halogenase family.