malF

malF is a gene found in Escherichia coli and many related bacteria that encodes the membrane protein MalF, a core component of the maltose/maltodextrin uptake system. This system is an ATP-binding cassette (ABC) transporter responsible for importing maltose and maltodextrins from the periplasm into the cytoplasm for metabolism. MalF, along with MalG, forms the transmembrane portion of the transporter, while MalK provides the ATPase activity that powers transport. The periplasmic maltose-binding protein MalE captures maltose and delivers it to the MalFGK2 complex, enabling substrate translocation across the inner membrane.

Genetically, malF is typically part of the maltose regulon, which also includes malE, malG, and malK. Expression of these genes is regulated by MalT, a transcriptional activator that responds to the presence of maltose or maltodextrins; cAMP-CRP–mediated signaling also influences regulon activity in various conditions. The operon architecture can vary among strains, but malE, malF, malG, and malK are commonly found in a coordinated cluster.

Functionally, the MalFGK2 transporter mediates the uptake of maltose and larger maltodextrins and is a classic model system for studying bacterial ABC transporters. The interaction between MalF, MalG, MalE, and MalK illustrates the cooperative mechanism by which binding protein–guided substrates are translocated with energy derived from ATP hydrolysis.

See also: maltose regulon, MalT, MalE, MalG, MalK, ABC transporter.