2.A.79 The Threonine/Serine Exporter (ThrE) Family
A single member of the ThrE family has been characterized: the ThrE protein of Corynebacterium glutamicum (Simic et al., 2002). This protein (489aas) exhibits 10 putative TMSs and catalyzes the pmf-dependent efflux of threonine and serine (Kruse et al., 2002). It has close homologues in Mycobacterium tuberculosis (Rv 3737; 529aas; pirB70798) and Strepomyces coelicolor (578aas; pirT36336. However more distant homologues, some of which consist of 'spliced' two-component systems, are also found in E. coli, Vibrio cholera, Xylella fastidiosa, Saccharomyces cerevisiae, Schizosaccharomyces pombe and Methanobacterium thermoautotrophicum. Thus, members of the ThrE family are diverse in sequence and are ubiquitous, being found in bacteria, archaea and eukaryotes (Eggeling and Sahm, 2003; Yen et al., 2002).
The transport reaction catalyzed by ThrE is:
threonine or serine (in) + H+ (out) ⇌ threonine or serine (out) + H+ (in)
Threonine/Serine exporter, ThrE (10 TMSs; DUF1212; Eggeling & Sahm, 2003)
Bacteria, archaea and eukarya
ThrE of Corynebacterium glutamicum (Q79VD1)
Pheromone-regulated membrane protein 10 of 1150 aas and 10 - 12 TMSs. CDD shows YjjP (DUF1212) and ProP (MFS) domains overlapping in the C-terminal transmembrane region. The N-terminal soluble domains shows sequence similarity to Insecticidal Vegetative Protein-3 Family (TC# 1.C.105.2.7; e-8).
Pheromone-regulated protein 10 of Candida albicans (Yeast)
ThrE homologue of Myxococcus xanthus
ThrE homologue of Propionibacterium acnes
PF06738 family protein
PF06738 family protein of Fusobacterium nucleatum
Putative 2-component glycine/alanine porter
Putative gly/ala porter of Treponema denticola
Uncharacterized protein of 147 aas and 5 TMSs.
UP of Clostridium clariflavum
Uncharacterized protein of 142 aas
UP of Paenibacillus sp. FSL H8-237
Uncharacterized protein of 430 aas and 10 TMSs in a 5 + 5 spatial arrangement.
UP of Mobilicoccus pelagius
Uncharacterized protein of 606 aas and 9 or 10 TMSs
UP of Mucor circinelloides (Mucormycosis agent) (Calyptromyces circinelloides)
Protein of unknown function, YjjP (5TMSs; DUF1212). Regulated by H-NS (Stratmann et al. 2008).
YjjP of E.coli (Q8FA71)
DUF1212 homologue of Rhodopseudomonas palustris