1: Proc Natl Acad Sci U S A. 2006 Sep 12;103(37):13676-81. Epub 2006 Aug 31.

NikR-operator complex structure and the mechanism of repressor activation by
metal ions.

Schreiter ER, Wang SC, Zamble DB, Drennan CL.

Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA
02139, USA.

Metal ion homeostasis is critical to the survival of all cells. Regulation of
nickel concentrations in Escherichia coli is mediated by the NikR repressor via
nickel-induced transcriptional repression of the nickel ABC-type transporter,
NikABCDE. Here, we report two crystal structures of nickel-activated E. coli
NikR, the isolated repressor at 2.1 A resolution and in a complex with its
operator DNA sequence from the nik promoter at 3.1 A resolution. Along with the
previously published structure of apo-NikR, these structures allow us to evaluate
functional proposals for how metal ions activate NikR, delineate the drastic
conformational changes required for operator recognition, and describe the
formation of a second metal-binding site in the presence of DNA. They also
provide a rare set of structural views of a ligand-responsive transcription
factor in the unbound, ligand-induced, and DNA-bound states, establishing a model
system for the study of ligand-mediated effects on transcription factor function.

PMCID: PMC1564233
PMID: 16945905 [PubMed - indexed for MEDLINE]

Related Links

    Regulation of high affinity nickel uptake in bacteria. Ni2+-Dependent interaction
of NikR with wild-type and mutant operator sites. [J Biol Chem. 2000]
PMID:10787413

    Crystal structure of the nickel-responsive transcription factor NikR. [Nat Struct
Biol. 2003] PMID:12970756

    Metal-selective DNA-binding response of Escherichia coli NikR. [Biochemistry.
2004] PMID:15287730

    Protease digestion analysis of Escherichia coli NikR: evidence for conformational
stabilization with Ni(II). [J Biol Inorg Chem. 2005] PMID:16133200

    Nickel-specific response in the transcriptional regulator, Escherichia coli NikR.
[J Am Chem Soc. 2007] PMID:17397155

2: J Biol Chem. 2006 Sep 15;281(37):27492-502. Epub 2006 Jun 28.

Structural insights into HypB, a GTP-binding protein that regulates metal
binding.

Gasper R, Scrima A, Wittinghofer A.

Max-Planck-Institut für Molekulare Physiologie, Abteilung Strukturelle Biologie, 
Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.

HypB is a prokaryotic metal-binding guanine nucleotide-binding protein that is
essential for nickel incorporation into hydrogenases. Here we solved the x-ray
structure of HypB from Methanocaldococcus jannaschii. It shows that the G-domain 
has a different topology than the Ras-like proteins and belongs to the SIMIBI
(after Signal Recognition Particle, MinD and BioD) class of NTP-binding proteins.
We show that HypB undergoes nucleotide-dependent dimerization, which is
apparently a common feature of SIMIBI class G-proteins. The nucleotides are
located in the dimer interface and are contacted by both subunits. The active
site features residues from both subunits arguing that hydrolysis also requires
dimerization. Two metal-binding sites are found, one of which is dependent on the
state of bound nucleotide. A totally conserved ENV/IGNLV/ICP motif in switch II
relays the nucleotide binding with the metal ionbinding site. The homology with
NifH, the Fe protein subunit of nitrogenase, suggests a mechanistic model for the
switch-dependent incorporation of a metal ion into hydrogenases.


PMID: 16807243 [PubMed - indexed for MEDLINE]

Related Links

    GTP hydrolysis by HypB is essential for nickel insertion into hydrogenases of
Escherichia coli. [Eur J Biochem. 1995] PMID:7601092

    The crystal structure of the third signal-recognition particle GTPase FlhF
reveals a homodimer with bound GTP. [Proc Natl Acad Sci U S A. 2007]
PMID:17699634

    The product of the hypB gene, which is required for nickel incorporation into
hydrogenases, is a novel guanine nucleotide-binding protein. [J Bacteriol. 1993] 
PMID:8423137

    UreG, a chaperone in the urease assembly process, is an intrinsically
unstructured GTPase that specifically binds Zn2+. [J Biol Chem. 2005]
PMID:15542602

    Molecular basis for G protein control of the prokaryotic ATP sulfurylase. [Mol
Cell. 2006] PMID:16387658

3: Acta Crystallogr Sect F Struct Biol Cryst Commun. 2005 Nov 1;61(Pt 11):959-63.
Epub 2005 Oct 20.

The ybeY protein from Escherichia coli is a metalloprotein.

Zhan C, Fedorov EV, Shi W, Ramagopal UA, Thirumuruhan R, Manjasetty BA, Almo SC, 
Fiser A, Chance MR, Fedorov AA.

New York Structural Genomics Research Consortium (NYSGXRC), Albert Einstein
College of Medicine, Bronx, New York 10461, USA.

The three-dimensional crystallographic structure of the ybeY protein from
Escherichia coli (SwissProt entry P77385) is reported at 2.7 A resolution. YbeY
is a hypothetical protein that belongs to the UPF0054 family. The structure
reveals that the protein binds a metal ion in a tetrahedral geometry. Three
coordination sites are provided by histidine residues, while the fourth might be 
a water molecule that is not seen in the diffraction map because of its
relatively low resolution. X-ray fluorescence analysis of the purified protein
suggests that the metal is a nickel ion. The structure of ybeY and its sequence
similarity to a number of predicted metal-dependent hydrolases provides a
functional assignment for this protein family. The figures and tables of this
paper were prepared using semi-automated tools, termed the Autopublish server,
developed by the New York Structural GenomiX Research Consortium, with the goal
of facilitating the rapid publication of crystallographic structures that emanate
from worldwide Structural Genomics efforts, including the NIH-funded Protein
Structure Initiative.

PMCID: PMC1978141
PMID: 16511207 [PubMed - indexed for MEDLINE]

Related Links

    Crystal structure of a conserved hypothetical protein from Escherichia coli. [J
Struct Funct Genomics. 2002] PMID:12836674

    Metalloproteomics: high-throughput structural and functional annotation of
proteins in structural genomics. [Structure. 2005] PMID:16216579

    Crystal structure of the copper homeostasis protein (CutCm) from Shigella
flexneri at 1.7 A resolution: the first structure of a new sequence family of TIM
barrels. [Proteins. 2005] PMID:15624211

    The structure at 1.7 A resolution of the protein product of the At2g17340 gene
from Arabidopsis thaliana. [Acta Crystallogr Sect F Struct Biol Cryst Commun.
2005] PMID:16511115

    Structure of the molybdenum-cofactor biosynthesis protein MoaB of Escherichia
coli. [Acta Crystallogr D Biol Crystallogr. 2004] PMID:15159566

4: Protein Sci. 2006 Feb;15(2):269-80.

Crystal structural analysis and metal-dependent stability and activity studies of
the ColE7 endonuclease domain in complex with DNA/Zn2+ or inhibitor/Ni2+.

Doudeva LG, Huang H, Hsia KC, Shi Z, Li CL, Shen Y, Cheng YS, Yuan HS.

Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, Republic
of China.

The nuclease domain of ColE7 (N-ColE7) contains an H-N-H motif that folds in a
beta beta alpha-metal topology. Here we report the crystal structures of a
Zn2+-bound N-ColE7 (H545E mutant) in complex with a 12-bp duplex DNA and a
Ni2+-bound N-ColE7 in complex with the inhibitor Im7 at a resolution of 2.5 A and
2.0 A, respectively. Metal-dependent cleavage assays showed that N-ColE7 cleaves 
double-stranded DNA with a single metal ion cofactor, Ni2+, Mg2+, Mn2+, and Zn2+.
ColE7 purified from Escherichia coli contains an endogenous zinc ion that was not
replaced by Mg2+ at concentrations of <25 mM, indicating that zinc is the
physiologically relevant metal ion in N-ColE7 in host E. coli. In the crystal
structure of N-ColE7/DNA complex, the zinc ion is directly coordinated to three
histidines and the DNA scissile phosphate in a tetrahedral geometry. In contrast,
Ni2+ is bound in N-ColE7 in two different modes, to four ligands (three
histidines and one phosphate ion), or to five ligands with an additional water
molecule. These data suggest that the divalent metal ion in the His-metal finger 
motif can be coordinated to six ligands, such as Mg2+ in I-PpoI, Serratia
nuclease and Vvn, five ligands or four ligands, such as Ni2+ or Zn2+ in ColE7.
Universally, the metal ion in the His-metal finger motif is bound to the DNA
scissile phosphate and serves three roles during hydrolysis: polarization of the 
P-O bond for nucleophilic attack, stabilization of the phosphoanion transition
state and stabilization of the cleaved product.


PMID: 16434744 [PubMed - indexed for MEDLINE]

Related Links

    The conserved asparagine in the HNH motif serves an important structural role in 
metal finger endonucleases. [J Mol Biol. 2007] PMID:17368670

    Metal ions and phosphate binding in the H-N-H motif: crystal structures of the
nuclease domain of ColE7/Im7 in complex with a phosphate ion and different
divalent metal ions. [Protein Sci. 2002] PMID:12441392

    The zinc ion in the HNH motif of the endonuclease domain of colicin E7 is not
required for DNA binding but is essential for DNA hydrolysis. [Nucleic Acids Res.
2002] PMID:11917029

    The crystal structure of the nuclease domain of colicin E7 suggests a mechanism
for binding to double-stranded DNA by the H-N-H endonucleases. [J Mol Biol. 2002]
PMID:12441102

    The crystal structure of the DNase domain of colicin E7 in complex with its
inhibitor Im7 protein. [Structure. 1999] PMID:10368275

5: J Biol Chem. 2006 Apr 21;281(16):10968-75. Epub 2006 Jan 23.

Structure and activity of two metal ion-dependent acetylxylan esterases involved 
in plant cell wall degradation reveals a close similarity to peptidoglycan
deacetylases.

Taylor EJ, Gloster TM, Turkenburg JP, Vincent F, Brzozowski AM, Dupont C, Shareck
F, Centeno MS, Prates JA, Puchart V, Ferreira LM, Fontes CM, Biely P, Davies GJ.

Structural Biology Laboratory, Department of Chemistry, University of York,
Heslington, York YO10 5YW, United Kingdom.

The enzymatic degradation of plant cell wall xylan requires the concerted action 
of a diverse enzymatic syndicate. Among these enzymes are xylan esterases, which 
hydrolyze the O-acetyl substituents, primarily at the O-2 position of the xylan
backbone. All acetylxylan esterase structures described previously display a
alpha/beta hydrolase fold with a "Ser-His-Asp" catalytic triad. Here we report
the structures of two distinct acetylxylan esterases, those from Streptomyces
lividans and Clostridium thermocellum, in native and complex forms, with x-ray
data to between 1.6 and 1.0 A resolution. We show, using a novel linked assay
system with PNP-2-O-acetylxyloside and a beta-xylosidase, that the enzymes are
sugar-specific and metal ion-dependent and possess a single metal center with a
chemical preference for Co2+. Asp and His side chains complete the catalytic
machinery. Different metal ion preferences for the two enzymes may reflect the
surprising diversity with which the metal ion coordinates residues and ligands in
the active center environment of the S. lividans and C. thermocellum enzymes.
These "CE4" esterases involved in plant cell wall degradation are shown to be
closely related to the de-N-acetylases involved in chitin and peptidoglycan
degradation (Blair, D. E., Schuettelkopf, A. W., MacRae, J. I., and Aalten, D. M.
(2005) Proc. Natl. Acad. Sci. U. S. A., 102, 15429-15434), which form the NodB
deacetylase "superfamily."


PMID: 16431911 [PubMed - indexed for MEDLINE]

Related Links

    Structures of Bacillus subtilis PdaA, a family 4 carbohydrate esterase, and a
complex with N-acetyl-glucosamine. [FEBS Lett. 2004] PMID:15251431

    The structure of the feruloyl esterase module of xylanase 10B from Clostridium
thermocellum provides insights into substrate recognition. [Structure. 2001]
PMID:11738044

    The vicinal hydroxyl group is prerequisite for metal activation of Clostridium
thermocellum acetylxylan esterase. [Biochim Biophys Acta. 2007] PMID:17261352

    Identification of catalytically important amino acid residues of Streptomyces
lividans acetylxylan esterase A from carbohydrate esterase family 4. [Biochim
Biophys Acta. 2006] PMID:16434244

    Three-dimensional structure of the catalytic core of acetylxylan esterase from
Trichoderma reesei: insights into the deacetylation mechanism. [J Struct Biol.
2000] PMID:11243887

6: Biochemistry. 2005 Aug 23;44(33):11014-23.

Metal binding sites in proteins: identification and characterization by
paramagnetic NMR relaxation.

Jensen MR, Petersen G, Lauritzen C, Pedersen J, Led JJ.

Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 
Copenhagen Ø, Denmark.

A method is presented that allows the identification and quantitative
characterization of metal binding sites in proteins using paramagnetic nuclear
magnetic resonance spectroscopy. The method relies on the nonselective
longitudinal relaxation rates of the amide protons and their dependence on the
paramagnetic metal ion concentration and the pH, and on the three-dimensional
structure of the protein. The method is demonstrated using Escherichia coli
thioredoxin as a model protein and Ni(2+) as the paramagnetic metal ion. Through 
a least-squares analysis of the relaxation rates, it is found that Ni(2+) binds
to a series of specific sites on the surface of thioredoxin. The strongest
binding site is found near the N-terminus of the protein, where the metal ion is 
coordinated to the free NH(2) group of the N-terminal serine residue and the side
chain carboxylate group of the aspartic acid residue in position 2. In addition, 
Ni(2+) binds specifically but more weakly to the surface-exposed side chain
carboxylate groups of residues D10, D20, D47, and E85.


PMID: 16101285 [PubMed - indexed for MEDLINE]

Related Links

    Binding ability of a HHP-tagged protein towards Ni2+ studied by paramagnetic NMR 
relaxation: the possibility of obtaining long-range structure information. [J
Biomol NMR. 2004] PMID:15014231

    Metal-protein interactions: structure information from Ni(2+)-induced
pseudocontact shifts in a native nonmetalloprotein. [Biochemistry. 2006]
PMID:16846221

    pH dependence of amide chemical shifts in natively disordered polypeptides
detects medium-range interactions with ionizable residues. [Biophys J. 2005]
PMID:16113108

    Structural characterization of a paramagnetic metal-ion-assembled three-stranded 
alpha-helical coiled coil. [J Am Chem Soc. 2002] PMID:12224949

    Determination of the electron relaxation rates in paramagnetic metal complexes:
applicability of available NMR methods. [J Magn Reson. 2004] PMID:15040973

7: J Am Chem Soc. 2005 Jul 20;127(28):10075-82.

Crystallographic and spectroscopic evidence for high affinity binding of
FeEDTA(H2O)- to the periplasmic nickel transporter NikA.

Cherrier MV, Martin L, Cavazza C, Jacquamet L, Lemaire D, Gaillard J,
Fontecilla-Camps JC.

Laboratoire de Cristallographie et de Cristallogenèse des Protéines and
Laboratoire de Spectroscopie de Masse des Protéines, Institut de Biologie
Structurale J.P. Ebel (CEA-CNRS-UJF), 41 rue Jules Horowitz, 38027 Grenoble Cedex
1, France.

Because nickel is both essential and toxic to a great variety of organisms, its
detection and transport is highly regulated. In Escherichia coli and other
related Gram-negative bacteria, high affinity nickel transport depends on
proteins expressed by the nik operon. A central actor of this process is the
periplasmic NikA transport protein. A previous structural report has proposed
that nickel binds to NikA as a pentahydrate species. However, both stereochemical
considerations and X-ray absorption spectroscopic results are incompatible with
that interpretation. Here, we report the 1.8 A resolution structure of NikA and
show that it binds FeEDTA(H2O)- with very high affinity. In addition, we provide 
crystallographic evidence that a metal-EDTA complex was also bound to the
previously reported NikA structure. Our observations strongly suggest that nickel
transport in E. coli requires the binding of this metal ion to a metallophore
that bears significant resemblance to EDTA. They also provide a basis for the
potential use of NikA in the bioremediation of toxic transition metals and the
design of artificial metalloenzymes.


PMID: 16011372 [PubMed - indexed for MEDLINE]

Related Links

    Nickel binding to NikA: an additional binding site reconciles spectroscopy,
calorimetry and crystallography. [Acta Crystallogr D Biol Crystallogr. 2007]
PMID:17242515

    NikA binds heme: a new role for an Escherichia coli periplasmic nickel-binding
protein. [Biochemistry. 2007] PMID:17411076

    Identification of the nik gene cluster of Brucella suis: regulation and
contribution to urease activity. [J Bacteriol. 2001] PMID:11133934

    Crystal structures of the liganded and unliganded nickel-binding protein NikA
from Escherichia coli. [J Biol Chem. 2003] PMID:12960164

    Purification and characterization of the periplasmic nickel-binding protein NikA 
of Escherichia coli K12. [Eur J Biochem. 1995] PMID:7867647

8: J Bacteriol. 2005 Jul;187(14):4689-97.

Escherichia coli HypA is a zinc metalloprotein with a weak affinity for nickel.

Atanassova A, Zamble DB.

Department of Chemistry, University of Toronto, Lash Miller Chemical
Laboratories, Ontario, Canada.

The hyp operon encodes accessory proteins that are required for the maturation of
the [NiFe] hydrogenase enzymes and, in some organisms, for the production of
urease enzymes as well. HypA or a homologous protein is required for nickel
insertion into the hydrogenase precursor proteins. In this study, recombinant
HypA from Escherichia coli was purified and characterized in vitro. Metal
analysis was used to demonstrate that HypA simultaneously binds stoichiometric
Zn(2+) and stoichiometric Ni(2+). Competition experiments with a metallochromic
indicator reveal that HypA binds zinc with nanomolar affinity. Spectroscopic
analysis of cobalt-containing HypA provides evidence for a tetrathiolate
coordination sphere, suggesting that the zinc site has a structural role. In
addition, HypA can exist as several oligomeric complexes and the zinc content
modulates the quaternary structure of the protein. Fluorescence titration
experiments demonstrate that HypA binds nickel with micromolar affinity and that 
the presence of zinc does not dramatically affect the nickel-binding activity.
Finally, complex formation between HypA and HypB, another accessory protein
required for nickel insertion, was observed. These experiments suggest that HypA 
is an architectural component of the hydrogenase metallocenter assembly pathway
and that it may also have a direct role in the delivery of nickel to the
hydrogenase large subunit.

PMCID: PMC1169514
PMID: 15995183 [PubMed - indexed for MEDLINE]

Related Links

    Metal binding activity of the Escherichia coli hydrogenase maturation factor
HypB. [Biochemistry. 2005] PMID:16142921

    Characterization of Helicobacter pylori nickel metabolism accessory proteins
needed for maturation of both urease and hydrogenase. [J Bacteriol. 2003]
PMID:12533448

    Dependence of Helicobacter pylori urease activity on the nickel-sequestering
ability of the UreE accessory protein. [J Bacteriol. 2003] PMID:12896998

    Requirement of nickel metabolism proteins HypA and HypB for full activity of both
hydrogenase and urease in Helicobacter pylori. [Mol Microbiol. 2001]
PMID:11123699

    Interaction between the Helicobacter pylori accessory proteins HypA and UreE is
needed for urease maturation. [Microbiology. 2007] PMID:17464061

9: Trends Biochem Sci. 2005 Apr;30(4):213-9.

When X-rays modify the protein structure: radiation damage at work.

Carugo O, Djinović Carugo K.

Department of General Chemistry, University of Pavia, Via Taramelli 12, 27100
Pavia, Italy. carugo@tasc.infm.it

The majority of 3D structures of macromolecules are currently determined by
macromolecular crystallography, which employs the diffraction of X-rays on single
crystals. However, during diffraction experiments, the X-rays can damage the
protein crystals by ionization processes, especially when powerful X-ray sources 
at synchrotron facilities are used. This process of radiation damage generates
photo-electrons that can get trapped in protein moieties. The 3D structure
derived from such experiments can differ remarkably from the structure of the
native molecule. Recently, the crystal structures of different oxidation states
of horseradish peroxidase and nickel-containing superoxide dismutase were
determined using crystallographic redox titration performed during the exposure
of the crystals to the incident X-ray beam. Previous crystallographic analyses
have not shown the distinct structures of the active sites associated with the
redox state of the structural features of these enzymes. These new studies show
that, for protein moieties that are susceptible to radiation damage and prone to 
reduction by photo-electrons, care is required in both the design of the
diffraction experiment and the analysis and interpretation.


PMID: 15817398 [PubMed - indexed for MEDLINE]

Related Links

    Radiation damage to protein specimens from electron beam imaging and diffraction:
a mini-review of anti-damage approaches, with special reference to synchrotron
X-ray crystallography. [J Synchrotron Radiat. 2007] PMID:17211078

    Phasing macromolecular structures with UV-induced structural changes. [Structure.
2006] PMID:16615919

    On the coordination and oxidation states of the active-site copper ion in
prokaryotic Cu,Zn superoxide dismutases. [Biochem Biophys Res Commun. 1998]
PMID:9731178

    Reduction of X-ray-induced radiation damage of macromolecular crystals by data
collection at 15 K: a systematic study. [Acta Crystallogr D Biol Crystallogr.
2007] PMID:17327667

    Photoreduction of the active site of the metalloprotein putidaredoxin by
synchrotron radiation. [Acta Crystallogr D Biol Crystallogr. 2007] PMID:17704563

10: Biochemistry. 2004 Dec 14;43(49):15472-9.

YfiT from Bacillus subtilis is a probable metal-dependent hydrolase with an
unusual four-helix bundle topology.

Rajan SS, Yang X, Shuvalova L, Collart F, Anderson WF.

Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine,
Northwestern University, Chicago, Illinois 60611, USA.

YfiT, a 19-kDa polypeptide from Bacillus subtilis, belongs to a small sequence
family with members predominantly from Gram positive bacteria. We have determined
the crystal structure of YfiT in complex with Ni(2+) to a resolution of 1.7 A.
YfiT exists as a dimer and binds Ni(2+) in a 1:1 stoichiometry. The protein has
an unusual four-helix bundle topology and coordinates Ni(2+) in an octahedral
geometry with three conserved histidines and three waters. Although there is no
similarity in their overall structures, the coordination geometry of the metal
and the residues that constitute the putative active site in YfiT are similar to 
those of metalloproteases such as thermolysin. Our structural analyses suggest
that YfiT might function as a metal-dependent hydrolase.


PMID: 15581359 [PubMed - indexed for MEDLINE]

Related Links

    Crystal structure of a putative CN hydrolase from yeast. [Proteins. 2003]
PMID:12833551

    The purine repressor of Bacillus subtilis: a novel combination of domains adapted
for transcription regulation. [J Bacteriol. 2003] PMID:12837783

    The structure and ligand binding properties of the B. subtilis YkoF gene product,
a member of a novel family of thiamin/HMP-binding proteins. [J Mol Biol. 2004]
PMID:15451668

    Crystal structure of a phosphatase-resistant mutant of sporulation response
regulator Spo0F from Bacillus subtilis. [Structure. 1996] PMID:8805550

    Structural and functional analysis of PucM, a hydrolase in the ureide pathway and
a member of the transthyretin-related protein family. [Proc Natl Acad Sci U S A. 
2006] PMID:16782815

11: J Biol Chem. 2003 Oct 31;278(44):43728-35. Epub 2003 Aug 8.

YodA from Escherichia coli is a metal-binding, lipocalin-like protein.

David G, Blondeau K, Schiltz M, Penel S, Lewit-Bentley A.

Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, CNRS, CEA, MdR, 
BP. 34, 91898 Orsay Cedex, France.

We have determined the crystal structure of YodA, an Escherichia coli protein of 
unknown function. YodA had been identified under conditions of cadmium stress,
and we confirm that it binds metals such as cadmium and zinc. We have also found 
nickel bound in one of the crystal forms. YodA is composed of two domains: a main
lipocalin/calycin-like domain and a helical domain. The principal metal-binding
site lies on one side of the calycin domain, thus making YodA the first
metal-binding lipocalin known. Our experiments suggest that YodA expression may
be part of a more general stress response. From sequence analogy with the
C-terminal domain of a metal-binding receptor of a member of bacterial
ATP-binding cassette transporters, we propose a three-dimensional model for this 
receptor and suggest that YodA may have a receptor-type partner in E. coli.


PMID: 12909634 [PubMed - indexed for MEDLINE]

Related Links

    The membrane bound bacterial lipocalin Blc is a functional dimer with binding
preference for lysophospholipids. [FEBS Lett. 2006] PMID:16920109

    Crystal structure of the zinc-binding transport protein ZnuA from Escherichia
coli reveals an unexpected variation in metal coordination. [J Mol Biol. 2007]
PMID:17399739

    Crystallization and preliminary analysis of Escherichia coli YodA. [Acta
Crystallogr D Biol Crystallogr. 2002] PMID:12077457

    The crystal structure of the Escherichia coli lipocalin Blc suggests a possible
role in phospholipid binding. [FEBS Lett. 2004] PMID:15044022

    Structural studies of the Cpx pathway activator NlpE on the outer membrane of
Escherichia coli. [Structure. 2007] PMID:17698001