RÉSUMÉ
The discovery that enhancers are regulated transcription units, encoding eRNAs, has raised new questions about the mechanisms of their activation. Here, we report an unexpected molecular mechanism that underlies ligand-dependent enhancer activation, based on DNA nicking to relieve torsional stress from eRNA synthesis. Using dihydrotestosterone (DHT)-induced binding of androgen receptor (AR) to prostate cancer cell enhancers as a model, we show rapid recruitment, within minutes, of DNA topoisomerase I (TOP1) to a large cohort of AR-regulated enhancers. Furthermore, we show that the DNA nicking activity of TOP1 is a prerequisite for robust eRNA synthesis and enhancer activation and is kinetically accompanied by the recruitment of ATR and the MRN complex, followed by additional components of DNA damage repair machinery to the AR-regulated enhancers. Together, our studies reveal a linkage between eRNA synthesis and ligand-dependent TOP1-mediated nicking-a strategy exerting quantitative effects on eRNA expression in regulating AR-bound enhancer-dependent transcriptional programs.
Sujet(s)
ADN topoisomérases de type I/métabolisme , Éléments activateurs (génétique) , Régulation de l'expression des gènes , Récepteurs aux androgènes/métabolisme , Lignée cellulaire tumorale , Cassures simple-brin de l'ADN , Réparation de l'ADN , ADN topoisomérases de type I/génétique , Protéines de liaison à l'ADN/métabolisme , Techniques de knock-down de gènes , Protéines à homéodomaine/métabolisme , Humains , Protéine homologue de MRE11 , Facteurs de transcription/métabolisme , Transcription génétiqueRÉSUMÉ
The first structural representative of the domain of unknown function DUF2006 family, also known as Pfam family PF09410, comprises a lipocalin-like fold with domain duplication. The finding of the calycin signature in the N-terminal domain, combined with remote sequence similarity to two other protein families (PF07143 and PF08622) implicated in isoprenoid metabolism and the oxidative stress response, support an involvement in lipid metabolism. Clusters of conserved residues that interact with ligand mimetics suggest that the binding and regulation sites map to the N-terminal domain and to the interdomain interface, respectively.
Sujet(s)
Protéines bactériennes/composition chimique , Bases de données génétiques , Métabolisme lipidique , Nitrosomonas europaea/composition chimique , Séquence d'acides aminés , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Nitrosomonas europaea/métabolisme , Stress oxydatif , Structure tertiaire des protéines , Alignement de séquences , Similitude de séquences d'acides aminésRÉSUMÉ
The crystal structure of Dhaf4260 from Desulfitobacterium hafniense DCB-2 was determined by single-wavelength anomalous diffraction (SAD) to a resolution of 2.01â Å using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). This protein structure is the first representative of the PF04016 (DUF364) Pfam family and reveals a novel combination of two well known domains (an enolase N-terminal-like fold followed by a Rossmann-like domain). Structural and bioinformatic analyses reveal partial similarities to Rossmann-like methyltransferases, with residues from the enolase-like fold combining to form a unique active site that is likely to be involved in the condensation or hydrolysis of molecules implicated in the synthesis of flavins, pterins or other siderophores. The genome context of Dhaf4260 and homologs additionally supports a role in heavy-metal chelation.
Sujet(s)
Protéines bactériennes/composition chimique , Desulfitobacterium/composition chimique , Métaux lourds/composition chimique , Enolase/composition chimique , Pliage des protéines , Séquence d'acides aminés , Protéines bactériennes/métabolisme , Domaine catalytique , Cristallographie aux rayons X , Desulfitobacterium/métabolisme , Métaux lourds/métabolisme , Modèles moléculaires , Données de séquences moléculaires , Liaison aux protéines , Structure tertiaire des protéinesRÉSUMÉ
Proteins with the DUF2063 domain constitute a new Pfam family, PF09836. The crystal structure of a member of this family, NGO1945 from Neisseria gonorrhoeae, has been determined and reveals that the N-terminal DUF2063 domain is likely to be a DNA-binding domain. In conjunction with the rest of the protein, NGO1945 is likely to be involved in transcriptional regulation, which is consistent with genomic neighborhood analysis. Of the 216 currently known proteins that contain a DUF2063 domain, the most significant sequence homologs of NGO1945 (â¼40-99% sequence identity) are from various Neisseria and Haemophilus species. As these are important human pathogens, NGO1945 represents an interesting candidate for further exploration via biochemical studies and possible therapeutic intervention.
Sujet(s)
Protéines bactériennes/composition chimique , Régulation de l'expression des gènes , Neisseria gonorrhoeae/composition chimique , Transcription génétique , Séquence d'acides aminés , Protéines bactériennes/génétique , Cristallographie aux rayons X , Génome bactérien , Modèles moléculaires , Données de séquences moléculaires , Neisseria gonorrhoeae/génétique , Structure quaternaire des protéines , Structure tertiaire des protéines , Similitude structurale de protéinesRÉSUMÉ
The crystal structures of BB2672 and SPO0826 were determined to resolutions of 1.7 and 2.1â Å by single-wavelength anomalous dispersion and multiple-wavelength anomalous dispersion, respectively, using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). These proteins are the first structural representatives of the PF06684 (DUF1185) Pfam family. Structural analysis revealed that both structures adopt a variant of the Bacillus chorismate mutase fold (BCM). The biological unit of both proteins is a hexamer and analysis of homologs indicates that the oligomer interface residues are highly conserved. The conformation of the critical regions for oligomerization appears to be dependent on pH or salt concentration, suggesting that this protein might be subject to environmental regulation. Structural similarities to BCM and genome-context analysis suggest a function in amino-acid synthesis.
Sujet(s)
Acides aminés/métabolisme , Bordetella bronchiseptica/enzymologie , Chorismate mutase/composition chimique , Pliage des protéines , Rhodobacteraceae/enzymologie , Séquence d'acides aminés , Bacillus/enzymologie , Chorismate mutase/métabolisme , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Structure quaternaire des protéines , Structure tertiaire des protéines , Similitude structurale de protéinesRÉSUMÉ
The crystal structure of Jann_2411 from Jannaschia sp. strain CCS1, a member of the Pfam PF07336 family classified as a domain of unknown function (DUF1470), was solved to a resolution of 1.45â Å by multiple-wavelength anomalous dispersion (MAD). This protein is the first structural representative of the DUF1470 Pfam family. Structural analysis revealed a two-domain organization, with the N-terminal domain presenting a new fold called the ABATE domain that may bind an as yet unknown ligand. The C-terminal domain forms a treble-clef zinc finger that is likely to be involved in DNA binding. Analysis of the Jann_2411 protein and the broader ABATE-domain family suggests a role as stress-induced transcriptional regulators.
Sujet(s)
Protéines bactériennes/composition chimique , Rhodobacteraceae/composition chimique , Séquence d'acides aminés , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Structure quaternaire des protéines , Structure tertiaire des protéines , Alignement de séquences , Doigts de zincRÉSUMÉ
The structure of LP2179, a member of the PF08866 (DUF1831) family, suggests a novel α+ß fold comprising two ß-sheets packed against a single helix. A remote structural similarity to two other uncharacterized protein families specific to the Bacillus genus (PF08868 and PF08968), as well as to prokaryotic S-adenosylmethionine decarboxylases, is consistent with a role in amino-acid metabolism. Genomic neighborhood analysis of LP2179 supports this functional assignment, which might also then be extended to PF08868 and PF08968.
Sujet(s)
Acides aminés/métabolisme , Protéines bactériennes/composition chimique , Lactobacillus plantarum/composition chimique , Pliage des protéines , Séquence d'acides aminés , Protéines bactériennes/métabolisme , Cristallographie aux rayons X , Lactobacillus plantarum/métabolisme , Modèles moléculaires , Données de séquences moléculaires , Structure tertiaire des protéines , Alignement de séquences , Similitude structurale de protéinesRÉSUMÉ
The crystal structure of PA1994 from Pseudomonas aeruginosa, a member of the Pfam PF06475 family classified as a domain of unknown function (DUF1089), reveals a novel fold comprising a 15-stranded ß-sheet wrapped around a single α-helix that assembles into a tight dimeric arrangement. The remote structural similarity to lipoprotein localization factors, in addition to the presence of an acidic pocket that is conserved in DUF1089 homologs, phospholipid-binding and sugar-binding proteins, indicate a role for PA1994 and the DUF1089 family in glycolipid metabolism. Genome-context analysis lends further support to the involvement of this family of proteins in glycolipid metabolism and indicates possible activation of DUF1089 homologs under conditions of bacterial cell-wall stress or host-pathogen interactions.
Sujet(s)
Protéines bactériennes/composition chimique , Glycolipides/métabolisme , Pliage des protéines , Pseudomonas aeruginosa/composition chimique , Séquence d'acides aminés , Protéines bactériennes/génétique , Protéines bactériennes/métabolisme , Cristallographie aux rayons X , Génome bactérien , Modèles moléculaires , Données de séquences moléculaires , Structure quaternaire des protéines , Structure tertiaire des protéines , Pseudomonas aeruginosa/génétique , Pseudomonas aeruginosa/métabolismeRÉSUMÉ
The crystal structures of SPO0140 and Sbal_2486 were determined using the semiautomated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). The structures revealed a conserved core with domain duplication and a superficial similarity of the C-terminal domain to pleckstrin homology-like folds. The conservation of the domain interface indicates a potential binding site that is likely to involve a nucleotide-based ligand, with genome-context and gene-fusion analyses additionally supporting a role for this family in signal transduction, possibly during oxidative stress.
Sujet(s)
Protéines bactériennes/composition chimique , Pliage des protéines , Rhodobacteraceae/composition chimique , Shewanella/composition chimique , Transduction du signal , Séquence d'acides aminés , Protéines bactériennes/génétique , Protéines bactériennes/métabolisme , Cristallographie aux rayons X , Génome bactérien , Modèles moléculaires , Données de séquences moléculaires , Structure secondaire des protéines , Structure tertiaire des protéines , Rhodobacteraceae/génétique , Rhodobacteraceae/métabolisme , Shewanella/génétique , Shewanella/métabolisme , Similitude structurale de protéinesRÉSUMÉ
The crystal structure of a putative NTPase, YP_001813558.1 from Exiguobacterium sibiricum 255-15 (PF09934, DUF2166) was determined to 1.78â Å resolution. YP_001813558.1 and its homologs (dimeric dUTPases, MazG proteins and HisE-encoded phosphoribosyl ATP pyrophosphohydrolases) form a superfamily of all-α-helical NTP pyrophosphatases. In dimeric dUTPase-like proteins, a central four-helix bundle forms the active site. However, in YP_001813558.1, an unexpected intertwined swapping of two of the helices that compose the conserved helix bundle results in a `linked dimer' that has not previously been observed for this family. Interestingly, despite this novel mode of dimerization, the metal-binding site for divalent cations, such as magnesium, that are essential for NTPase activity is still conserved. Furthermore, the active-site residues that are involved in sugar binding of the NTPs are also conserved when compared with other α-helical NTPases, but those that recognize the nucleotide bases are not conserved, suggesting a different substrate specificity.
Sujet(s)
Bacillales/enzymologie , Pyrophosphatases/composition chimique , Séquence d'acides aminés , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Multimérisation de protéines , Structure quaternaire des protéines , Structure tertiaire des protéines , Similitude structurale de protéinesRÉSUMÉ
The crystal structures of the proteins encoded by the YP_749275.1 and YP_001095227.1 genes from Shewanella frigidimarina and S. loihica, respectively, have been determined at 1.8 and 2.25â Å resolution, respectively. These proteins are members of a novel family of bacterial proteins that adopt the α/ß SpoIIAA-like fold found in STAS and CRAL-TRIO domains. Despite sharing 54% sequence identity, these two proteins adopt distinct conformations arising from different dispositions of their α2 and α3 helices. In the `open' conformation (YP_001095227.1), these helices are 15â Å apart, leading to the creation of a deep nonpolar cavity. In the `closed' structure (YP_749275.1), the helices partially unfold and rearrange, occluding the cavity and decreasing the solvent-exposed hydrophobic surface. These two complementary structures are reminiscent of the conformational switch in CRAL-TRIO carriers of hydrophobic compounds. It is suggested that both proteins may associate with the lipid bilayer in their `open' monomeric state by inserting their amphiphilic helices, α2 and α3, into the lipid bilayer. These bacterial proteins may function as carriers of nonpolar substances or as interfacially activated enzymes.
Sujet(s)
Protéines bactériennes/composition chimique , Membrane cellulaire/composition chimique , Shewanella/composition chimique , Séquence d'acides aminés , Protéines bactériennes/métabolisme , Membrane cellulaire/métabolisme , Cristallographie aux rayons X , Ligands , Modèles moléculaires , Données de séquences moléculaires , Liaison aux protéines , Structure quaternaire des protéines , Structure tertiaire des protéines , Alignement de séquences , Similitude de séquences d'acides aminés , Shewanella/métabolisme , Similitude structurale de protéinesRÉSUMÉ
KPN03535 (gi|152972051) is a putative lipoprotein of unknown function that is secreted by Klebsiella pneumoniae MGH 78578. The crystal structure reveals that despite a lack of any detectable sequence similarity to known structures, it is a novel variant of the OB-fold and structurally similar to the bacterial Cpx-pathway protein NlpE, single-stranded DNA-binding (SSB) proteins and toxins. K. pneumoniae MGH 78578 forms part of the normal human skin, mouth and gut flora and is an opportunistic pathogen that is linked to about 8% of all hospital-acquired infections in the USA. This structure provides the foundation for further investigations into this divergent member of the OB-fold family.
Sujet(s)
Protéines bactériennes/composition chimique , Klebsiella pneumoniae/composition chimique , Lipoprotéines/composition chimique , Séquence d'acides aminés , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Pliage des protéines , Structure tertiaire des protéinesRÉSUMÉ
Proteins that contain the DUF2874 domain constitute a new Pfam family PF11396. Members of this family have predominantly been identified in microbes found in the human gut and oral cavity. The crystal structure of one member of this family, BVU2987 from Bacteroides vulgatus, has been determined, revealing a ß-lactamase inhibitor protein-like structure with a tandem repeat of domains. Sequence analysis and structural comparisons reveal that BVU2987 and other DUF2874 proteins are related to ß-lactamase inhibitor protein, PepSY and SmpA_OmlA proteins and hence are likely to function as inhibitory proteins.
Sujet(s)
Bacteroides/composition chimique , Protéines périplasmiques/composition chimique , Séquence d'acides aminés , Bacteroides/métabolisme , Séquence conservée , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Protéines périplasmiques/métabolisme , Liaison aux protéines , Structure tertiaire des protéines , Alignement de séquences , Similitude structurale de protéinesRÉSUMÉ
The crystal structure of the Bacteroides thetaiotaomicron protein BT_3984 was determined to a resolution of 1.7â Å and was the first structure to be determined from the extensive SusD family of polysaccharide-binding proteins. SusD is an essential component of the sus operon that defines the paradigm for glycan utilization in dominant members of the human gut microbiota. Structural analysis of BT_3984 revealed an N-terminal region containing several tetratricopeptide repeats (TPRs), while the signature C-terminal region is less structured and contains extensive loop regions. Sequence and structure analysis of BT_3984 suggests the presence of binding interfaces for other proteins from the polysaccharide-utilization complex.
Sujet(s)
Protéines bactériennes/composition chimique , Bacteroides/composition chimique , Séquence d'acides aminés , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Structure tertiaire des protéines , Similitude structurale de protéinesRÉSUMÉ
BT1062 from Bacteroides thetaiotaomicron is a homolog of Mfa2 (PGN0288 or PG0179), which is a component of the minor fimbriae in Porphyromonas gingivalis. The crystal structure of BT1062 revealed a conserved fold that is widely adopted by fimbrial components.
Sujet(s)
Bacteroides/composition chimique , Protéines de fimbriae/composition chimique , Fimbriae bactériens/composition chimique , Pliage des protéines , Séquence d'acides aminés , Bacteroides/génétique , Cristallographie aux rayons X , Protéines de fimbriae/génétique , Modèles moléculaires , Données de séquences moléculaires , Structure tertiaire des protéines , Alignement de séquences , Similitude structurale de protéinesRÉSUMÉ
BT2081 from Bacteroides thetaiotaomicron (GenBank accession code NP_810994.1) is a member of a novel protein family consisting of over 160 members, most of which are found in the different classes of Bacteroidetes. Genome-context analysis lends support to the involvement of this family in carbohydrate metabolism, which plays a key role in B. thetaiotaomicron as a predominant bacterial symbiont in the human distal gut microbiome. The crystal structure of BT2081 at 2.05â Å resolution represents the first structure from this new protein family. BT2081 consists of an N-terminal domain, which adopts a ß-sandwich immunoglobulin-like fold, and a larger C-terminal domain with a ß-sandwich jelly-roll fold. Structural analyses reveal that both domains are similar to those found in various carbohydrate-active enzymes. The C-terminal ß-jelly-roll domain contains a potential carbohydrate-binding site that is highly conserved among BT2081 homologs and is situated in the same location as the carbohydrate-binding sites that are found in structurally similar glycoside hydrolases (GHs). However, in BT2081 this site is partially occluded by surrounding loops, which results in a deep solvent-accessible pocket rather than a shallower solvent-exposed cleft.
Sujet(s)
Protéines bactériennes/composition chimique , Bacteroides/composition chimique , Métabolisme glucidique , Séquence d'acides aminés , Protéines bactériennes/métabolisme , Bacteroides/métabolisme , Sites de fixation , Glucides/composition chimique , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Structure tertiaire des protéines , Alignement de séquences , Similitude structurale de protéinesRÉSUMÉ
Membrane-attack complex/perforin (MACPF) proteins are transmembrane pore-forming proteins that are important in both human immunity and the virulence of pathogens. Bacterial MACPFs are found in diverse bacterial species, including most human gut-associated Bacteroides species. The crystal structure of a bacterial MACPF-domain-containing protein BT_3439 (Bth-MACPF) from B. thetaiotaomicron, a predominant member of the mammalian intestinal microbiota, has been determined. Bth-MACPF contains a membrane-attack complex/perforin (MACPF) domain and two novel C-terminal domains that resemble ribonuclease H and interleukin 8, respectively. The entire protein adopts a flat crescent shape, characteristic of other MACPF proteins, that may be important for oligomerization. This Bth-MACPF structure provides new features and insights not observed in two previous MACPF structures. Genomic context analysis infers that Bth-MACPF may be involved in a novel protein-transport or nutrient-uptake system, suggesting an important role for these MACPF proteins, which were likely to have been inherited from eukaryotes via horizontal gene transfer, in the adaptation of commensal bacteria to the host environment.
Sujet(s)
Protéines bactériennes/composition chimique , Bacteroides/composition chimique , Perforine/composition chimique , Séquence d'acides aminés , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Structure tertiaire des protéines , Alignement de séquences , Similitude structurale de protéinesRÉSUMÉ
Chorismate mutase/prephenate dehydrogenase from Haemophilus influenzae Rd KW20 is a bifunctional enzyme that catalyzes the rearrangement of chorismate to prephenate and the NAD(P)(+)-dependent oxidative decarboxylation of prephenate to 4-hydroxyphenylpyruvate in tyrosine biosynthesis. The crystal structure of the prephenate dehydrogenase component (HinfPDH) of the TyrA protein from H. influenzae Rd KW20 in complex with the inhibitor tyrosine and cofactor NAD(+) has been determined to 2.0â Å resolution. HinfPDH is a dimeric enzyme, with each monomer consisting of an N-terminal α/ß dinucleotide-binding domain and a C-terminal α-helical dimerization domain. The structure reveals key active-site residues at the domain interface, including His200, Arg297 and Ser179 that are involved in catalysis and/or ligand binding and are highly conserved in TyrA proteins from all three kingdoms of life. Tyrosine is bound directly at the catalytic site, suggesting that it is a competitive inhibitor of HinfPDH. Comparisons with its structural homologues reveal important differences around the active site, including the absence of an α-ß motif in HinfPDH that is present in other TyrA proteins, such as Synechocystis sp. arogenate dehydrogenase. Residues from this motif are involved in discrimination between NADP(+) and NAD(+). The loop between ß5 and ß6 in the N-terminal domain is much shorter in HinfPDH and an extra helix is present at the C-terminus. Furthermore, HinfPDH adopts a more closed conformation compared with TyrA proteins that do not have tyrosine bound. This conformational change brings the substrate, cofactor and active-site residues into close proximity for catalysis. An ionic network consisting of Arg297 (a key residue for tyrosine binding), a water molecule, Asp206 (from the loop between ß5 and ß6) and Arg365' (from the additional C-terminal helix of the adjacent monomer) is observed that might be involved in gating the active site.
Sujet(s)
Protéines bactériennes/composition chimique , Haemophilus influenzae/enzymologie , Complexes multienzymatiques/composition chimique , Prephenate dehydrogenase/composition chimique , Cristallographie aux rayons XRÉSUMÉ
Examination of the genomic context for members of the FmdE Pfam family (PF02663), such as the protein encoded by the fmdE gene from the methanogenic archaeon Methanobacterium thermoautotrophicum, indicates that 13 of them are co-transcribed with genes encoding subunits of molybdenum formylmethanofuran dehydrogenase (EC 1.2.99.5), an enzyme that is involved in microbial methane production. Here, the first crystal structures from PF02663 are described, representing two bacterial and one archaeal species: B8FYU2_DESHY from the anaerobic dehalogenating bacterium Desulfitobacterium hafniense DCB-2, Q2LQ23_SYNAS from the syntrophic bacterium Syntrophus aciditrophicus SB and Q9HJ63_THEAC from the thermoacidophilic archaeon Thermoplasma acidophilum. Two of these proteins, Q9HJ63_THEAC and Q2LQ23_SYNAS, contain two domains: an N-terminal thioredoxin-like α+ß core domain (NTD) consisting of a five-stranded, mixed ß-sheet flanked by several α-helices and a C-terminal zinc-finger domain (CTD). B8FYU2_DESHY, on the other hand, is composed solely of the NTD. The CTD of Q9HJ63_THEAC and Q2LQ23_SYNAS is best characterized as a treble-clef zinc finger. Two significant structural differences between Q9HJ63_THEAC and Q2LQ23_SYNAS involve their metal binding. First, zinc is bound to the putative active site on the NTD of Q9HJ63_THEAC, but is absent from the NTD of Q2LQ23_SYNAS. Second, whereas the structure of the CTD of Q2LQ23_SYNAS shows four Cys side chains within coordination distance of the Zn atom, the structure of Q9HJ63_THEAC is atypical for a treble-cleft zinc finger in that three Cys side chains and an Asp side chain are within coordination distance of the zinc.
Sujet(s)
Aldehyde oxidoreductases/composition chimique , Desulfitobacterium/enzymologie , Méthane/biosynthèse , Doigts de zinc , Séquence d'acides aminés , Cristallographie aux rayons X , Modèles moléculaires , Données de séquences moléculaires , Structure secondaire des protéines , Structure tertiaire des protéines , Similitude structurale de protéinesRÉSUMÉ
In the plant pathogen Xanthomonas campestris pv. campestris, the product of the tcmJ gene, XcTcmJ, encodes a protein belonging to the RmlC family of cupins. XcTcmJ was crystallized in a monoclinic space group (C2) in the presence of zinc acetate and the structure was determined to 1.6â Å resolution. Previously, the apo structure has been reported in the absence of any bound metal ion [Chin et al. (2006), Proteins, 65, 1046-1050]. The most significant difference between the apo structure and the structure of XcTcmJ described here is a reorganization of the binding site for zinc acetate, which was most likely acquired from the crystallization solution. This site is located in the conserved metal ion-binding domain at the putative active site of XcTcmJ. In addition, an acetate was also bound within coordination distance of the zinc. In order to accommodate this binding, rearrangement of a conserved histidine ligand is required as well as several nearby residues within and around the putative active site. These observations indicate that binding of zinc serves a functional role in this cupin protein.