C. elegans Multidrug Resistance Protein 5 (MRP-5) Transports Vitamin B12 from the Intestine to the Gonad to Support Embryonic Development

SUMMARY Vitamin B12 functions as a cofactor for methionine synthase to produce the anabolic methyl donor S-adenosylmethionine (SAM) and for methylmalonyl-CoA mutase to catabolize the short chain fatty acid propionate. In the nematode Caenorhabditis elegans, maternally supplied vitamin B12 is required for the development of her offspring. However, the mechanism for transporting vitamin B12 from the mother’s intestine into her gonad is not yet known. Here, we use RNAi of more than 200 transporters with a vitamin B12-sensor transgene to identify the ABC transporter MRP-5 as a candidate vitamin B12 exporter. We show that injection of vitamin B12 into the gonad of mrp-5 knockdown mothers rescues embryonic lethality in her offspring. Altogether, our findings identify a maternal mechanism for the transit of an essential vitamin to support the development of the next generation.