Misplaced Pages

Lysine Exporters are a superfamily of transmembrane proteins which export amino acids, lipids and heavy metal ions. They provide ionic homeostasis, play a role in cell envelope assembly, and protect from excessive concentrations of heavy metals in cytoplasm. The superfamily was named based on the early discovery of the LysE carrier protein of Corynebacterium glutamicum.

Families

2.A.75 - The L-Lysine Exporter (LysE) Family

2.A.76 - The Resistance to Homoserine/Threonine (RhtB) Family

2.A.77 - The Cadmium Resistance (CadD) Family

2.A.95 - The 6TMS Neutral Amino Acid Transporter (NAAT) Family

2.A.106 - The Ca:H Antiporter-2 (CaCA2) Family

2.A.107 - The Mn exporter (MntP) Family

2.A.108 - The Iron/Lead Transporter (ILT) Family

2.A.109 - The Tellurium Ion Resistance (TerC) Family

2.A.113 - The Nickel/Cobalt Transporter (NicO) Family

2.A.116 - The Peptidoglycolipid Addressing Protein (GAP) Family

5.A.1 - The Disulfide Bond Oxidoreductase D (DsbD) Family

The LysE family

Two members of the LysE family (LysE of Corynebacterium glutamicum (TC# 2.A.75.1.1) and ArgO of E. coli) have been functionally characterized, but functionally uncharacterized homologues are encoded within the genomes of many bacteria including Bacillus subtilis, Mycobacterium tuberculosis, Aeromonas salmonicida, Helicobacter pylori, Vibrio cholerae and Yersinia pestis. Thus, LysE family members are found widely distributed in Gram-negative and Gram-positive bacteria.

Structure

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. However, some evidence suggests a 6 TMS topology.

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.

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.

Generalized Transport Reaction

The generalized transport reaction for LysE is:

Lysine (in) Lysine (out) .

References

 This article incorporates text available under the CC BY 4.0 license.

1. 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. PMID 10943564.
2. ^ Tsu BV, Saier MH (2015-01-01). "The LysE Superfamily of Transport Proteins Involved in Cell Physiology and Pathogenesis". PLOS ONE. 10 (10): e0137184. Bibcode:2015PLoSO..1037184T. doi:10.1371/journal.pone.0137184. PMC 4608589. PMID 26474485.
3. ^ Vrljic 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. PMID 8971704. S2CID 26112791.
4. Saier, MH Jr. "2.A.75 The L-Lysine Exporter (LysE) Family". Transporter Classification Database. Saier Lab Bioinformatics Group / SDSC.
5. Nandineni MR, Gowrishankar J (June 2004). "Evidence for an arginine exporter encoded by yggA (argO) that is regulated by the LysR-type transcriptional regulator ArgP in Escherichia coli". Journal of Bacteriology. 186 (11): 3539–46. doi:10.1128/JB.186.11.3539-3546.2004. PMC 415761. PMID 15150242.

• Biology

• Solute carrier family
• Protein families