Methionine ABC transporter (MetNIQ) (MetNIQ)

The Methionine ABC transporter, commonly referred to as the MetNIQ or MetD system, is a high-affinity nutrient uptake complex found in a wide range of bacteria, including Escherichia coli, Streptococcus pneumoniae, and Neisseria species. It is composed of three essential subunits: the ATPase MetN, the transmembrane permease MetI, and the substrate-binding protein MetQ. This system is responsible for the energy-dependent transport of L- and D-methionine from the extracellular environment into the bacterial cytoplasm, where it supports critical functions such as protein synthesis, S-adenosylmethionine (SAM) production, and bacterial virulence. In human pathogens like Neisseria gonorrhoeae, the surface-exposed MetQ protein is a major vaccine candidate due to its high conservation and ability to elicit protective immune responses. While the bacterial system is a target for novel antibacterials, the human functional equivalent is the L-type amino acid transporter 1 (LAT1/SLC7A5), which is a significant therapeutic target in oncology. Cancer cells often exhibit methionine addiction, and inhibitors like JPH203 (Nanvuranlat) are being developed to disrupt methionine uptake and suppress tumor growth.

Other names

MetDMethionine transport systemMetNIMetQNIL-methionine-binding lipoprotein MetQSystem L (human functional equivalent)D-methionine transport system