9.A.4 The YggT or Fanciful K+ Uptake-B (FkuB; YggT) Family

Nakamura et al. (1996) identified a DNA fragment from Vibrio alginolyticus which complemented the growth defect of a K+ uptake deficient mutant of E. coli TK420. Two of the residing genes on this fragment were reported to be required for growth in synthetic medium containing 10 mM K+ and 100 mM Na+. K+ uptake was restored by introducing these genes.

Homologues of FkuB (most of 180-200 aas or of 80-100 aas) include the E. coli YggT protein. The larger members of this family contain a repeat found in many integral membrane proteins; the smaller members have just one.

In the E. coli YggT protein (188 aas), residues 1-91 are repeated (92-182). Half sized homologues (e.g., the YggT homologues of Geobacter uraniumreducens; 105 aas; gi#88936025, and Bacillus anthracis; YlmG; 87 aas; gi#49180675, both have just 2 TMSs). Other homologues are much larger with more than four TMSs (e.g., from Wolbachia; 992 aas; 6-8 putative TMSs with a large N-terminal hydrophilic domain and a smaller C-terminal hydrophilic domain) and the Type IV secretory pathway VirB6 component of Wolbachia (gi#58585051; 1040 aas; 8 putative TMSs with a long hydrophilic N-terminus of >600 aas).

The proposed transport function catalyzed by FkuB is:

K+ (out) → K+ (in)



This family belongs to the .

 

References:

Nakamura, T., Y. Katoh, Y. Shimizu, Y. Matsuba, and T. Unemoto. (1996). Cloning and sequencing of novel genes from Vibrio alginolyticus that support the growth of K+ uptake-deficient mutant of Escherichia coli. Biochim. Biophys. Acta 1277: 201-208.

Examples:

TC#NameOrganismal TypeExample
9.A.4.1.1The 185 aa, 4 putative TMS K+ uptake protein, FkuBBacteriaFkuB of Vibrio alginolyticus (P52059)
 
9.A.4.1.2The 188 aa, 4 putative TMS YggT protein of unknown functionBacteriaYggT of E. coli (P64564)
 
Examples:

TC#NameOrganismal TypeExample
9.A.4.2.1The 87 aa 2 putative TMS YlmG protein of unknown functionBacteriaYlmG of Bacillus anthracis (gi #49180675)
 
9.A.4.2.2

YggT family member of 181 aas

Red Algae

YggT homologue of Galdieria sulphuraria

 
9.A.4.2.3

YggT family protein of 157 aas

Algae

YggT homologue of Galdieria sulphuraria

 
9.A.4.2.4

Uncharacterized protein of 193 aas and 4 TMSs.

Spirochaetes

UP of Treponema pedis

 
Examples:

TC#NameOrganismal TypeExample
9.A.4.3.1

The 992 aa 6-8 putative TMS protein (PfamPF04610 family), TrbL

Bacteria

TrbL of Wolbachia endosymbiont of Drosophila melanogaster (gi #42410430)