Probable S-adenosyl-L-methionine-dependent methyltransferase. Plays a role in both resistance to oxidative damage and heme uptake/utilization. Also protects H.influenzae from tellurite exposure in vitro; however, since H.influenzae grows only in humans, it is unlikely to encounter tellurite in its natural environment, and it is thus probable that tellurite resistance does not represent a biologically relevant role of TehB (By similarity). Transcription is significantly up-regulated during growth in iron/heme-restricted conditions. Belongs to the TehB family.