Catalyzes the nucleophilic attack of one alpha-aminobutanoate moiety from SAM onto D-histidine to produce the intermediate (2S)-2-amino-4-{[(1R)-1-carboxy-2-(1H-imidazol-4-yl)ethyl]amino}butanoate. Functions in the biosynthesis of the metallophore staphylopine, which is involved in the acquisition of nickel, cobalt, zinc, copper, and iron, and thus enables bacterial growth inside the host, where metal access is limited. Therefore, this enzyme probably contributes to staphylococcal virulence (PubMed:27230378, PubMed:29091735). Appears to be specific for D-histidine as substrate (PubMed:29091735). D-histidine + S-adenosyl-L-methionine = (2S)-2-amino-4-{[(1R)-1-carboxy-2-(1H-imidazol-4-yl)ethyl]amino}butanoate + H(+) + S-methyl-5'-thioadenosine kcat is 1.79 min(-1). Up-regulated in metal-poor media. Cells lacking this gene produce neither staphylopine nor the biosynthetic intermediate 2-amino-4-{[1-carboxy-2-(1H-imidazol-4-yl)ethyl]amino}butanoate. They also show a decrease in the intracellular content of nickel, copper, cobalt, iron, and zinc. Belongs to the methyltransferase superfamily. CntL family.