Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The . gov means it’s official VSports app下载. Federal government websites often end in . gov or . mil. Before sharing sensitive information, make sure you’re on a federal government site. .

Https

The site is secure V体育官网. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. .

Review
. 2003 Apr 1;100(7):3584-8.
doi: 10.1073/pnas.0630018100. Epub 2003 Mar 24.

Enterobactin: an archetype for microbial iron transport

Kenneth N Raymond  1 , Emily A Dertz, Sanggoo S Kim
Affiliations
Review

Enterobactin: an archetype for microbial iron transport

Kenneth N Raymond et al. Proc Natl Acad Sci U S A. .

Abstract

Bacteria have aggressive acquisition processes for iron, an essential nutrient. Siderophores are small iron chelators that facilitate cellular iron transport VSports手机版. The siderophore enterobactin is a triscatechol derivative of a cyclic triserine lactone. Studies of the chemistry, regulation, synthesis, recognition, and transport of enterobactin make it perhaps the best understood of the siderophore-mediated iron uptake systems, displaying a lot of function packed into this small molecule. However, recent surprises include the isolation of corynebactin, a closely related trithreonine triscatechol derivative lactone first found in Gram-positive bacteria, and the crystal structure of a ferric enterobactin complex of a protein identified as an antibacterial component of the human innate immune system. .

PubMed Disclaimer

Figures

Figure 1
Figure 1
Schematic and space filling structures of enterobactin and its ferric complex. (Upper) The catechol, amide linkage and triserine ring components of enterobactin, and the conformation charge, driven by hydrogen bonding, following deprotonation (or metal complexation). (Lower Right) The structure of the V(IV) complex (30), considered to be a close model of the Fe(III) complex. (Lower Left) A computer-generated structure of uncomplexed enterobactin based on the trilactone structure of Seebach et al. (52) and appended catecholamide groups as seen in the crystal structure of an enterobactin analog (79). Note how hydrogen bonding locks the catechol group into one of two rigid conformations, the interconversion of which is triggered by deprotonation/metal complexation.
Scheme 1
Scheme 1
Figure 2
Figure 2
A pictorial scheme shows the transmembrane topology of the FeEnt uptake proteins and how they function. In an iron-deficient state, iron receptors proliferate among the outer membrane (OM) proteins. FepA is a channel protein composed of a β-barrel and an N-terminal gate protein (see Fig. 3). The FepA receptor is highly specific and recognizes the iron binding domain and amide linkage domains of FeEnt. The gating movement of FepA is transduced by the complex TonB–ExbB–ExbD, which is anchored in the cytoplamic membrane (CM). FepB delivers FeEnt to the cytoplasmic pores formed by FepD and FepG. It appears that the cytoplasmic ATPase, FepC, provides energy to assist the uptake through the inner membrane. FeEnt esterase, which is encoded by the fes gene, catalyzes hydrolytic cleavage of the backbone, leading to the intracellular release of iron.
Figure 3
Figure 3
The crystallographic structure of unliganded FepA (Protein Data Bank code 1FEB). (Left) A view perpendicular to the channel axis. The periplasm side of the outer membrane is at the bottom. (Right) A view down the axis from the extracellular space. FepA is monomeric (porins are trimeric) and composed of an antiparallel β-stranded barrel (571 residues) and an N-terminal plug domain (153 residues, colored blue) anchored within the barrel. The right-handed twist barrel is ≈70 Å in height and the ellipsoidal cross-section dimension is 30 × 40 Å. The β-barrel is tilted ≈45° to the axis of the barrel. The extracellular loops of the β-barrel extend ≈30 Å above the membrane.
Figure 4
Figure 4
The structures of the two trilactone siderophores: enterobactin (Left) and corynebactin (Right). (Center) The chemical structure of corynebactin (which has a glycine spacer between the catechol ligands and the trilactone ring) is shown (that for enterobactin is in Fig. 1). The conformation for the 12-membered triserine ring of enterobactin places both the lactone carbonyl and the exocyclic amine groups in axial positions. The conformation for the trithreonine ring of corynebactin is inverted, with ester carbonyls equatorial. The consequence is that, while the ferric enterobactin complex is Δ (Lower Left) the ferric corynebactin complex is Λ (Lower Right).
See this image and copyright information in PMC

References

    1. Raymond K N, Carrano C J. Acc Chem Res. 1979;12:183–190.
    1. Neilands J B. J Biol Chem. 1995;270:26723–26726. - "VSports" PubMed
    1. Aisen P, Enns C, Wessling-Resnick M. Int J Biochem Cell Biol. 2001;33:940–959. - PubMed
    1. De Freitas J M, Meneghini R. Mutat Res. 2001;475:153–159. - PubMed
    1. Braun V, Killmann H. Trends Biochem Sci. 1999;24:104–109. - PubMed

Publication types (VSports在线直播)

"VSports app下载" Substances

"VSports最新版本" LinkOut - more resources