Jiménez R, Cervantes C

Language: Spanish
References: 16
Page: 3-11
PDF size: 90.20 Kb.

ABSTRACT

Membrane transporters are proteins that play essential roles for the adequate functioning of all living organisms. In bacteria, nutrient uptake and extrusion of toxic compounds are among the main functions of these proteins. The structure of transporters is mainly given by their interactions with the cell membrane, thus making topological analysis, i.e. determination of the number and orientation of transmembrane segments (TMSs) with respect to the lipid bilayer, fundamental to understand their function. Information on membrane topology may be used for the identification of essential residues or as an approach to understand the evolutionary origin of transporters. A variety of methods has been designed to study the topology of membrane transporters. These methods are based on genetic modifications that allow to locate specific regions of the protein of interest within the membrane. In this work we summarize the reported findings on the topology of bacterial transporters, with emphasis on systems transporting inorganic ions. Of a total 111 transporters studied, two groups predominate: one that crosses only once the membrane and another group possessing 12 TMSs. In addition, many proteins contain 4, 6, 8 or 10 TMSs.

REFERENCES

1. von Heijne G (1992) Membrane protein structure prediction. Hydrophobicity analysis and the positiveinside rule. J Mol Biol 225:487-94.

2. Moller S, Croning MD, Apweiler R (2001) Evaluation of methods for the prediction of membrane spanning regions. Bioinformatics 17:646-53.

3. van Geest M, Lolkema JS (2000) Membrane topology and insertion of membrane proteins: search for topogenic signals. Microbiol Mol Biol Rev 64:13-33.

4. Derman AI, Beckwith J (1991) Escherichia coli alkaline phosphatase fails to acquire disulfide bonds when retained in the cytoplasm. J Bacteriol 173:7719-22.

5. Snyder WB, Silhavy TJ (1995) Beta-galactosidase is inactivated by intermolecular disulfide bonds and is toxic when secreted to the periplasm of Escherichia coli. J Bacteriol 177:953-63.

6. Feilmeier BJ, Iseminger G, Schroeder D, Webber H, Phillips GJ (2000) Green fluorescent protein functions as a reporter for protein localization in Escherichia coli. J Bacteriol 182:4068-76.

7. Adler J, Bibi E (2002) Membrane topology of the multidrug transporter MdfA: complementary gene fusion studies reveal a nonessential C-terminal domain. J Bacteriol 184:3313-20.

8. Gouffi K, Gerard F, Santini CL, Wu LF (2004) Dual topology of the Escherichia coli TatA protein. J Biol Chem 279:11608-15.

9. Newton SM, Klebba PE, Michel V, Hofnung M, Charbit A (1996) Topology of the membrane protein LamB by epitope tagging and a comparison with the X-ray model. J Bacteriol 178:3447-56.

10. Mondigler M, Ehrmann M (1996) Site-specific proteolysis of the Escherichia coli SecA protein in vivo. J Bacteriol 178:2986-88.

11. Aguilera S, Aguilar ME, Chávez MP, López-Meza JE, Pedraza-Reyes M, Campos-García J, Cervantes C (2004) Essential residues in the chromate transporter ChrA of Pseudomonas aeruginosa. FEMS Microbiol Lett 232:107-12.

12. Saier MH Jr (2003) Tracing pathways of transport protein evolution. Mol Microbiol 48:1145-56.

13. Rensing C, Ghosh M, Rosen BP (1999) Families of softmetal- ion-transporting ATPases. J Bacteriol 181:5891-97.

14. Saaf A, Baars L, von Heijne G (2001) The internal repeats in the Na+/Ca2+ exchanger-related Escherichia coli protein YrbG have opposite membrane topologies. J Biol Chem 276:18905-07.

15. Wallin E, von Heijne G (1998) Genome-wide analysis of integral membrane proteins from eubacterial, archaean, and eukaryotic organisms. Protein Sci 7:1029-38.

16. Manoil C, Beckwith J (1986) A genetic approach to analyzing membrane protein topology. Science 233:1403-08.