Periplasmic binding proteins

The determination of the structure of the iron transporter, ferric-binding, protein (hFBP)t from Haemophilus influenzae (Bruns et ah, 1997) at 0.16 nm resolution shows that it is a member of the transferrin superfamily, which includes both the transferrins and a number of periplasmic binding proteins (PBP). The PBPs transport a wide variety of nutrients, including sugars, amino acids and ions, across the periplasm from the outer to the inner (plasma) membrane in bacteria (see Chapter 3). Iron binding by transferrins (see below) requires concomitant binding of a carbonate anion, which is located at the N-terminus of a helix. This corresponds to the site at which the anions are specifically bound in the bacterial periplasmic sulfate- and... 

The first of the haem uptake systems to be characterized at molecular level was that of Yersinia enterolitica, which closely resembles a typical siderophore uptake system (Stojiljkovic and Hantke, 1992, 1994), including a TonB-dependent outer membrane receptor for haem, a periplasmic binding protein, and a cytoplasmic membrane transport system. There also seems to be a protein that degrades haem and liberates haem iron within the cell. TonB-dependent outer membrane receptor proteins for haem have been cloned and sequenced from Shigella dysenteriae and E. coli (Mills and Payne, 1995 Torres and Payne, 1997), while in Vibrio cholera two genes are required for haem utilization, one an outer membrane receptor a second which may have a TonB-like function (Henderson and Payne, 1994). 

Baraquet, C., Theraulaz, L., Guiral, M., Lafitte, D., Mejean, V., and Jourlin-Castelli, C. (2006) TorT, a member of a new periplasmic binding protein family, triggers induction of the Tor respiratory system upon trimethylamine N-oxide electron-acceptor binding in Escherichia coli.J. Biol. Chem. 281, 38189-38199. 

Prossnitz, E., Nikaido, K., Ulbrich, S.J., and Ames, G.F. (1988) Formaldehyde and photoactivatable cross-linking of the periplasmic binding protein to a membrane component of the histidine transport system of Salmonella typhimurium. J. Biol. Chem. 263, 17917-17920. 

O Hara, P. J., Sheppard, P. O., Thpgersen, H., et al. (1993) The ligand-binding domain in metabotropic glutamate receptor is related to bacterial periplasmic binding proteins. Neuron 11,41-52. 

Karpowich, N. K., Huang, H. H., Smith, P. C. and Hunt, J. F. (2003). Crystal structures of the BtuF periplasmic-binding protein for vitamin B12 suggest a functionally important reduction in protein mobility upon ligand binding, J. Biol. Chem., 278, 8429-8434. 

Angerer, A., Gaisser, S. and Braun, V. (1990). Nucleotide sequences of the sfuA, sfuB, and sfuC genes of Serratia marcescens suggest a periplasmic-binding-protein-dependent iron transport mechanism, J. Bacteriol., 172, 572-578. 

The uptake of siderophore-iron complexes by Gram-negative bacteria is energy dependent and occurs via specific outer membrane proteins. In the periplasmic space, it binds to its cognate periplasmic binding protein and is then actively transported across the cytoplasmic membrane by an ATP-trans-porter protein. Three principal mechanisms for transport through the outer membrane have been described ... 

Likewise, for zinc, bacteria have developed active uptake systems (Hantke, 2001). In many bacteria the high-affinity Zn2+ uptake system uses an ABC transporter of the cluster 9 family, which mostly transports zinc and manganese and is found in nearly all bacterial species. First identified in cyanobacteria and pathogenic streptococci, but also found in E. coli, the system is encoded by three genes ZnuABC and consists of an outer membrane permease ZnuB, a periplasmic-binding protein ZnuA and a cytoplasmic ATPase ZnuC. Low-affinity transporters of the ZIP family, described later in this chapter, such as ZupT, have also been shown to be involved in bacterial zinc uptake. 

Navarro, C., Wu, L. F. and Mandrand-Berthelot, M. A. (1993) The nik operon oi Escherichia coli encodes a periplasmic binding-protein-dependent transport system for nickel. Mol. 

The periplasmic binding proteins function together with the other subunits of the ABC transporter system. One of the best understood systems is encoded by the histidine transport operon of Salmonella typhimurium,445 453 There are four genes his (encoding the histidine-binding protein), hisQ, hisM, and hisP. 

In E. coli arsenate is reduced to arsenite by a glutare-doxin-andNADH-dependentsystem s Thearsenite as well as antimonite and tellurite are pumped out by an ATP-dependent transporter. The genes for reductase, periplasmic-binding protein, and transporter components are encoded in a conjugative plas-midA1 A quite similar system functions in yeast.)... 

Quiocho, F. A., Atomic Structures of periplasmic binding-proteins and the high-affinity active-transport systems in bacteria. Phil. Trans. Royal Soc. Ser. B, Biol. Sci. 1990, 326, 341-352. 

Sack JS, Saper MA, Quiocho FA. Periplasmic binding protein structure and function. Refined X-ray structures of the leucine/isoleucine/valine-binding protein and its complex with leucine. Journal of Molecular Biology 1989, 206, 171-191. 

Fig. 2. Possible evolutionary development of the transferrin family, showing also the proposed relationship of bacterial periplasmic binding proteins (Section III.D).

A remarkable feature of transferrin structure, discovered when the human lactoferrin structure was determined (67, 85), is the striking similarity with a group of bacterial binding proteins. These proteins, the bacterial periplasmic binding proteins, bind and transport certain small molecules, such as sugars, amino acids and oxyanions, through the periplasmic space before delivering them via specific receptors in the bacterial cell wall (111). They thus share with transferrins the... 

After Fe + siderophores have docked at the binding pocket of the outer-membrane receptors of E. colt, translocation into the periplasmic space is mediated by the TonB complex. Once released into the periplasm, siderophores are rapidly bound by the specific periplasmic binding proteins FhuD (hydroxamate siderophores), FepB (enterobactin), and FecB (ferric dicitrate).FhuD, for example, exhibits a broad substrate specificity for a variety of hydroxamate siderophores including ferrichrome, coprogen, aerobactin, ferrioxamine B, shizokinen, rhodotorulic acid, and the antibiotic albomycin. The dissociation constants of FhuD with these siderophores range from 0.3 to 5.4 X-ray structures of FhuD... 

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