Catalyzes the formation of N(7)-methylguanine at position 46 (m7G46) in tRNA (By similarity). trmB lp_1458 MRVRNKPWAPKLIAAHPELITEDPTQLKGRWQSRFAKPQPLQIEVGSGKGQFIIEMAKRHPEINYVAIEIQTSVIAIILKKLVEAPLPNLQLAHADGQAVTAFFEPHEVDRLYLNFSDPWPKSRHEKRRLTYKSFLSSYREVLKPNGQIEFKTDNRGLFEFSLTSMNNFGMQFEQVWLDLHAVATPEDNVETEYEQKFSAAGPIYKIIATFPAK 214 tRNA (guanine-N(7)-)-methyltransferase TRMB_LACPL tRNA(m7G46)-methyltransferase