These proteins are 190-240 amino acyl residues in length and possess six hydrophobic regions. PhoA fusion analyses of LysE of C. glutamicum provided evidence for a 5 transmembrane α-helical spanner (TMS) typology with the N-terminus inside and the C-terminus outside.[3] However, some evidence suggests a 6 TMS topology.[4]
Function
LysE appears to catalyze unidirectional efflux of L-lysine (and other basic amino acids such as L-arginine), and it provides the sole route for L-lysine excretion. The energy source is believed to be the proton motive force (H+ antiport). The E. coli ArgO homologue (TC# 2.A.75.1.2) effluxes arginine and possibly lysine and canavanine as well.[5]
Early studies showed that the LysE family is related to the RhtB family (TC #2.A.76) as well as the CadD family (TC #2.A.77) based both on the similar sizes and topologies of their members and on PSI-BLAST results.[3]
Generalized Transport Reaction
The generalized transport reaction for LysE is:
Lysine (in) + [nH+ (out) or nOH− (in)] Lysine (out) + [nH+ (in) or nOH− (out)].
References
This article incorporates text available under the CC BY 4.0 license.
^Vrljic M, Garg J, Bellmann A, Wachi S, Freudl R, Malecki MJ, Sahm H, Kozina VJ, Eggeling L, Saier MH, Eggeling L, Saier MH (November 1999). "The LysE superfamily: topology of the lysine exporter LysE of Corynebacterium glutamicum, a paradyme for a novel superfamily of transmembrane solute translocators". Journal of Molecular Microbiology and Biotechnology. 1 (2): 327–36. PMID10943564.
^ abVrljic M, Sahm H, Eggeling L (December 1996). "A new type of transporter with a new type of cellular function: L-lysine export from Corynebacterium glutamicum". Molecular Microbiology. 22 (5): 815–26. doi:10.1046/j.1365-2958.1996.01527.x. PMID8971704. S2CID26112791.
