Evaluation of novel pyrazol-4-yl pyridine derivatives possessing arylsulfonamide tethers as c-Jun N-terminal kinase (JNK) inhibitors in leukemia cells

A series of 36 pyrazol-4-yl pyridine derivatives (8a-i, 9a-i, 10a-i, and 11a-i) was designed, synthesized, and evaluated for its antiproliferative activity over NCI-60 cancer cell line panel and inhibitory effect against JNK isoforms (JNK1, JNK2, and JNK3). All the synthesized compounds were tested against the NCI-60 cancer cell line panel. Compounds 11b, 11c, 11g, and 11i were selected to determine their GI50s and exerted a superior potency over the reference standard SP600125 against the tested cell lines. 11c showed a GI50 of 1.28 μM against K562 leukemic cells. Vero cells were used to assess 11c cytotoxicity compared to the tested cancer cells. The target compounds were tested against hJNK isoforms in which compound 11e exhibited the highest potency against JNK isoforms with IC50 values of 1.81, 12.7, and 10.5 nM against JNK1, JNK2, and JNK3, respectively. Kinase profiling of 11e showed higher JNK selectivity in 50 kinase panels. Compounds 11c and 11e showed cell population arrest at the G2/M phase, induced early apoptosis, and slightly inhibited beclin-1 production at higher concentrations in K562 leukemia cells relative to SP600125. NanoBRET assay of 11e showed intracellular JNK1 inhibition with an IC50 of 2.81 μM. Also, it inhibited CYP2D6 and 3A4 with different extent and its hERG activity showed little cardiac toxicity with an IC50 of 4.82 μM. hJNK3 was used as a template to generate the hJNK1 crystal structure to explore the binding mode of 11e (PDB ID: 8ENJ) with a resolution of 2.8 °A and showed a typical type I kinase inhibition against hJNK1. Binding energy scores showed that selectivity of 11e towards JNK1 could be attributed to additional hydrophobic interactions relative to JNK3.

Post-insertion technique to introduce targeting moieties in milk exosomes for targeted drug delivery

BACKGROUND

Recently, increased attention has been given on exosomes as ideal nanocarriers of drugs owing to their intrinsic properties that facilitate the transport of biomolecular cargos. However, large-scale exosome production remains a major challenge in the clinical application of exosome-based drug delivery systems. Considering its biocompatibility and stability, bovine milk is a suitable natural source for large-scale and stable exosome production. Because the active-targeting ability of drug carriers is essential to maximize therapeutic efficacy and minimize side effects, precise membrane functionalization strategies are required to enable tissue-specific delivery of milk exosomes with difficulty in post-isolation modification.

METHODS

In this study, the membrane functionalization of a milk exosome platform modified using a simple post-insertion method was examined comprehensively. Exosomes were engineered from bovine milk (mExo) with surface-tunable modifications for the delivery of tumor-targeting doxorubicin (Dox). The surface modification of mExo was achieved through the hydrophobic insertion of folate (FA)-conjugated lipids.

RESULTS

We have confirmed the stable integration of functionalized PE-lipid chains into the mExo membrane through an optimized post-insertion technique, thereby effectively enhancing the surface functionality of mExo. Indeed, the results revealed that FA-modified mExo (mExo-FA) improved cellular uptake in cancer cells via FA receptor (FR)-mediated endocytosis. The designed mExo-FA selectively delivered Dox to FR-positive tumor cells and triggered notable tumor cell death, as confirmed by in vitro and in vivo analyses.

CONCLUSIONS

This simple and easy method for post-isolation modification of the exosomal surface may be used to develop milk-exosome-based drug delivery systems.

Structural and functional characterization of USP47 reveals a hot spot for inhibitor design

USP47 is widely involved in tumor development, metastasis, and other processes while performing a more regulatory role in inflammatory responses, myocardial infarction, and neuronal development. In this study, we investigate the functional and biochemical properties of USP47, whereby depleting USP47 inhibited cancer cell growth in a p53-dependent manner-a phenomenon that enhances during the simultaneous knockdown of USP7. Full-length USP47 shows higher deubiquitinase activity than the catalytic domain. The crystal structures of the catalytic domain, in its free and ubiquitin-bound states, reveal that the misaligned catalytic triads, ultimately, become aligned upon ubiquitin-binding, similar to USP7, thereby becoming ready for catalysis. Yet, the composition and lengths of BL1, BL2, and BL3 of USP47 differ from those for USP7, and they contribute to the observed selectivity. Our study provides molecular details of USP47 regulation, substrate recognition, and the hotspots for drug discovery by targeting USP47.

Structural basis for CEP192-mediated regulation of centrosomal AURKA

Aurora kinase A (AURKA) performs critical functions in mitosis. Thus, the activity and subcellular localization of AURKA are tightly regulated and depend on diverse factors including interactions with the multiple binding cofactors. How these different cofactors regulate AURKA to elicit different levels of activity at distinct subcellular locations and times is poorly understood. Here, we identified a conserved region of CEP192, the major cofactor of AURKA, that mediates the interaction with AURKA. Quantitative binding studies were performed to map the interactions of a conserved helix (Helix-1) within CEP192. The crystal structure of Helix-1 bound to AURKA revealed a distinct binding site that is different from other cofactor proteins such as TPX2. Inhibiting the interaction between Helix-1 and AURKA in cells led to the mitotic defects, demonstrating the importance of the interaction. Collectively, we revealed a structural basis for the CEP192-mediated AURKA regulation at the centrosome, which is distinct from TPX2-mediated regulation on the spindle microtubule.

USP35 dimer prevents its degradation by E3 ligase CHIP through auto-deubiquitinating activity

Recently, a number of reports on the importance of USP35 in cancer have been published. However, very little is known about the exact mechanism by which USP35 activity is regulated. Here, we show the possible regulation of USP35 activity and the structural specificity affecting its function by analyzing various fragments of USP35. Interestingly, the catalytic domain of USP35 alone does not exhibit deubiquitinating activity; in contrast, the C-terminal domain and insertion region in the catalytic domain is required for full USP35 activity. Additionally, through its C-terminal domain, USP35 forms a homodimer that prevents USP35 degradation. CHIP bound to HSP90 interacts with and ubiquitinates USP35. However, when fully functional USP35 undergoes auto-deubiquitination, which attenuates CHIP-mediated ubiquitination. Finally, USP35 dimer is required for deubiquitination of the substrate Aurora B and regulation of faithful mitotic progression. The properties of USP35 identified in this study are a unique homodimer structure, regulation of deubiquitinating activity through this, and utilization of a novel E3 ligase involved in USP35 auto-deubiquitination, which adds another complexity to the regulation of deubiquitinating enzymes.

The complex of Fas-associated factor 1 with Hsp70 stabilizes the adherens junction integrity by suppressing RhoA activation

Fas-associated factor 1 (FAF1) is a scaffolding protein that plays multiple functions, and dysregulation of FAF1 is associated with many types of diseases such as cancers. FAF1 contains multiple ubiquitin-related domains (UBA, UBL1, UBL2, UAS, and UBX), each domain interacting with a specific partner. In particular, the interaction of UBL1 with heat shock protein 70 (Hsp70) is associated with tumor formation, although the molecular understanding remains unknown. In this study, the structural analysis revealed that His160 of FAF1 is important for its interaction with Hsp70. The association of Hsp70 with FAF1 is required for the interaction with IQGAP1. FAF1 negatively regulates RhoA activation by FAF1–Hsp70 complex formation, which then interacts with IQGAP1. These steps play a key role in maintaining the stability of cell-to-cell junction. We conclude that FAF1 plays a critical role in the structure and function of adherens junction during tissue homeostasis and morphogenesis by suppressing RhoA activation, which induces the activation of Rho-associated protein kinase, phosphorylation of myosin light chain, formation of actin stress fiber, and disruption of adherens junction. In addition, depletion of FAF1 increased collective invasion in a 3D spheroid cell culture. These results provide insight into how the FAF1–Hsp70 complex acts as a novel regulator of the adherens junction integrity. The complex can be a potential therapeutic target to inhibit tumorigenesis and metastasis.

Structural optimization of 4-(imidazol-5-yl)pyridine derivatives affords broad-spectrum anticancer agents with selective B-RAFV600E/p38α kinase inhibitory activity: Synthesis, in vitro assays and in silico study

In the current article, we introduce design of a new series of 4-(imidazol-5-yl)pyridines with improved anticancer activity and selective B-RAF^V600E/p38α kinase inhibitory activity. Based on a previous work, a group of structural modifications were applied affording the new potential antiproliferative agents. Towards extensive biological assessment of the target compounds, an in vitro anticancer assay was conducted over NCI 60-cancer cell lines panel representing blood, lung, colon, CNS, skin, ovary, renal, prostate, and breast cancers. Compounds 7c, 7d, 8b, 9b, 9c, 10c, 10d, and 11b exhibited the highest potency among the tested compounds and demonstrated sub-micromolar or one-digit micromolar GI₅₀ values against the majority of the employed cell lines. Compound 10c emerged as the most potent agent with nano-molar activity over most of the cells and incredible activity against melanoma (MDA-MB-435) cell line (GI₅₀ 70 nM). It is much more potent than sorafenib, the clinically used anticancer drug, against almost all the NCI-60 cell lines. Further cell-based mechanistic assays showed that compound 10c induced cell cycle arrest and promoted apoptosis in K562, MCF-7 and HT29 cancer cell lines. In addition, compound 10c induced autophagy in the three cancer cell lines. Kinase profiling of 10c showed its inhibitory effects and selectivity towards B-RAF^V600E and p38α kinases with IC₅₀ values of 1.84 and 0.726 µM, respectively. Docking of compound 10c disclosed its high affinity in the kinases pockets. Compound 10c represent a promising anticancer agent, that could be optimized in order to improve its kinase activity aiming at developing potential anticancer agents. The conformational stability of compound 10c in the active site of B-RAF^V600E and p38α kinases was studied by applying molecular dynamic simulation of the compound in the two kinases for 600 ns in comparison to the native ligands.

Biological Aging and Periodontal Disease: Analysis of NHANES (2001-2002)

INTRODUCTION

Periodontitis is a chronic inflammatory disease caused by multiple potential contributing factors such as bacterial biofilm infection of the tissues surrounding the teeth and environmental determinants and a dysregulated host response for modifying and resolving the inflammation. Because periodontal disease is a major public health concern with substantial increases in the prevalence and severity in aging populations, previous studies of periodontitis tended to approach the disease as an age-associated outcome across the life span. However, few investigations have considered that, as a chronic noncommunicable disease, periodontitis may not simply be a disease that increases with age but may contribute to more rapid biologic aging.

OBJECTIVES

Increasing population data supports the potential disconnect between chronological aging and biologic aging, which would contribute to the heterogeneity of aging phenotypes within chronologic ages across populations. Thus, our aim was to test whether periodontal disease affects biological aging across the life span.

METHODS

The prevalence of periodontitis in the adult US population is a portion of the assessment of the National Health and Nutrition Examination Survey (NHANES), which has been ongoing since 1971 through 2-y cycles sampling populations across the country. We used NHANES 2001-2002 to test the hypothesis that the presence/severity of periodontal disease as an exposure variable would negatively affect telomere length, a measure of biological aging, and that this relationship is modified by factors that also affect the progression of periodontitis, such as sex, race/ethnicity, and smoking.

RESULTS

The data demonstrated a significant impact of periodontitis on decreasing telomere lengths across the life span. These differences were modulated by age, sex, race/ethnicity, and smoking within the population.

CONCLUSION

The findings lay the groundwork for future studies documenting broader effects on biological aging parameters as well as potential intervention strategies for periodontitis in driving unhealthy aging processes.

KNOWLEDGE TRANSFER STATEMENT

Periodontitis is a chronic inflammatory disease and dysregulated host response. Shortening of telomeres is a reflection of biologic aging. Decreased telomere lengths with periodontitis are seemingly related to chronic infection and persistent local and systemic inflammation. These findings suggest that periodontitis is not simply a disease of aging but may also transmit chronic systemic signals that could affect more rapid biological aging. Clinicians can use this outcome to recognize the role of periodontitis in driving unhealthy aging processes in patients.

2-Anilinoquinoline based arylamides as broad spectrum anticancer agents with B-RAFV600E/C-RAF kinase inhibitory effects: Design, synthesis, in vitro cell-based and oncogenic kinase assessments

Prompted by the urgent demand for identification of new anticancer agents with improved potency and efficacy, a new series of arylamides incorporating the privileged 2-anilinoquinoline scaffold has been designed, synthesized, and biologically assessed. Aiming at extensive evaluation of the target compounds' potency and spectrum, a panel of 60 clinically important cancer cell lines representing nine cancer types has been used. Compounds 9a and 9c, with piperazine substituted phenyl ring, emerged as the most active members surpassing the anticancer potencies of the FDA-approved drug imatinib. They elicited sub-micromolar or one-digit micromolar GI₅₀ values over the majority of tested cancer cells including multidrug resistant (MDR) cells like colon HCT-15, renal TK-10 and UO-31, and ovarian NCI/ADR-RES. In vitro mechanistic study showed that compounds 9a and 9c could trigger morphological changes, apoptosis and cell cycle arrest in HCT-116 colon cancer cells. Besides, compound 9c altered microtubule polymerization pattern in a similar fashion to paclitaxel. Kinase screening of 9c disclosed its inhibitory activity over B-RAF^V600E and C-RAF kinases with IC₅₀ values of 0.888 μM and 0.229 μM, respectively. Taken together, the current report presents compounds 9a and 9c as promising broad-spectrum potent anticancer candidates, which could be considered for further development of new anticancer drugs.

Development of a Polo-like Kinase-1 Polo-Box Domain Inhibitor as a Tumor Growth Suppressor in Mice Models

Polo-like kinase-1 (Plk1) plays a key role in mitosis and has been identified as an attractive anticancer drug target. Plk1 consists of two drug-targeting sites, namely, N-terminal kinase domain (KD) and C-terminal polo-box domain (PBD). As KD-targeting inhibitors are associated with severe side effects, here we report on the pyrazole-based Plk1 PBD inhibitor, KBJK557, which showed a remarkable in vitro anticancer effect by inducing Plk1 delocalization, mitotic arrest, and apoptosis in HeLa cells. Further, in vivo optical imaging analysis and antitumorigenic activities in mouse xenograft models demonstrate that KBJK557 preferentially accumulates in cancer cells and selectively inhibits cancer cell proliferation. Pharmacokinetic profiles and partition coefficients suggest that KBJK557 was exposed in the blood and circulated through the organs with an intermediate level of clearance (t1/2, 7.73 h). The present investigation offers a strategy for specifically targeting cancer using a newly identified small-molecule inhibitor that targets the Plk1 PBD.

Assay Systems for Profiling Deubiquitinating Activity

Deubiquitinating enzymes regulate various cellular processes, particularly protein degradation, localization, and protein-protein interactions. The dysregulation of deubiquitinating enzyme (DUB) activity has been linked to several diseases; however, the function of many DUBs has not been identified. Therefore, the development of methods to assess DUB activity is important to identify novel DUBs, characterize DUB selectivity, and profile dynamic DUB substrates. Here, we review various methods of evaluating DUB activity using cell lysates or purified DUBs, as well as the types of probes used in these methods. In addition, we introduce some techniques that can deliver DUB probes into the cells and cell-permeable activity-based probes to directly visualize and quantify DUB activity in live cells. This review could contribute to the development of DUB inhibitors by providing important information on the characteristics and applications of various probes used to evaluate and detect DUB activity in vitro and in vivo.

Rationally designed redirection of natural killer cells anchoring a cytotoxic ligand for pancreatic cancer treatment

The emergence of T-cell engineering with chimeric antigen receptors (CARs) has led to attractive therapeutics; however, autologous CAR-T cells are associated with poor clinical outcomes in solid tumors because of low safety and efficacy. Therefore, the aim of our study was to develop a CAR therapy with enhanced cytotoxicity against solid cancer using allogeneic NK cells. In this study, we engineered "off-the-shelf" NK cells to redirect them towards pancreatic ductal adenocarcinoma (PDAC) by improving their target-specific cytotoxic potential. By integrated bioinformatic and clinicopathological analyses, folate receptor alpha (FRα) and death receptor 4 (DR4) were significantly highly expressed in patient-derived tumor cells. The combined expression of FRα and DR4/5 was associated with inferior clinical outcomes, therefore indicating their use as potential targets for biomolecular treatment. Thus, FRα and DR4 expression pattern can be a strong prognostic factor as promising therapeutic targets for the treatment of PDAC. For effective PDAC treatment, allogeneic CAR-NK cells were reprogrammed to carry an apoptosis-inducing ligand and to redirect them towards FRα and initiate DR4/5-mediated cancer-selective cell death in FRα- and DR4/5-positive tumors. As a result, the redirected cytotoxic ligand-loaded NK cells led to a significantly enhanced tumor-selective apoptosis. Accordingly, use of allogeneic CAR-NK cells that respond to FRα and DR4/5 double-positive cancers might improve clinical outcomes based on personal genome profiles. Thus, therapeutic modalities based on allogeneic NK cells can potentially be used to treat large numbers of patients with optimally selective cytotoxicity.

USP47 Promotes Tumorigenesis by Negative Regulation of p53 through Deubiquitinating Ribosomal Protein S2

p53 is activated in response to cellular stresses such as DNA damage, oxidative stress, and especially ribosomal stress. Although the regulations of p53 by E3 ligase and deubiquitinating enzymes (DUBs) have been described, the cellular roles of DUB associated with ribosomal stress have not been well studied. In this study, we report that Ubiquitin Specific Protease 47 (USP47) functions as an important regulator of p53. We show that ubiquitinated ribosomal protein S2 (RPS2) by Mouse double minute 2 homolog (MDM2) is deubiquitinated by USP47. USP47 inhibits the interaction between RPS2 and MDM2 thereby alleviating RPS2-mediated suppression of MDM2 under normal conditions. However, dissociation of USP47 leads to RPS2 binding to MDM2, which is required for the suppression of MDM2, consequently inducing up-regulation of the p53 level under ribosomal stress. Finally, we show that depletion of USP47 induces p53 and therefore inhibits cell proliferation, colony formation, and tumor progression in cancer cell lines and a mouse xenograft model. These findings suggest that USP47 could be a potential therapeutic target for cancer.

Structural and Molecular Basis for Katanin-Mediated Severing of Glutamylated Microtubules

Katanin was the first microtubule (MT)-severing enzyme discovered, but how katanin executes MT severing remains poorly understood. Here, we report X-ray crystal structures of the apo and ATPγS-bound states of the catalytic AAA domain of human katanin p60 at 3.0 and 2.9 Å resolution, respectively. Comparison of the two structures reveals conformational changes induced by ATP binding and how such changes ensure hexamer stability. Moreover, we uncover structural details of pore loops (PLs) and show that Arg283, a residue unique to katanin among MT-severing enzymes, protrudes from PL1 and lines the entry of the catalytic pore. Functional studies suggest that PL1 and Arg283 play essential roles in the recognition and remodeling of the glutamylated, C-terminal tubulin tail and regulation of axon growth. In addition, domain-swapping experiments in katanin and spastin suggest that the non-homologous N-terminal region, which contains the MT-interacting and trafficking domain and a linker, confers specificity to the severing process.

Ribosomal protein S2 interplays with MDM2 to induce p53

The MDM2-p53 pathway is crucial for maintenance of p53 homeostasis. Some ribosomal proteins (RPs) play critical roles in regulating p53 by interacting with MDM2. However, the role and functional mechanism of each RP in MDM2-p53 pathway still remain unknown. In this study, we found that Ribosomal Protein S2 (RPS2) is a new regulator of MDM2-P53 signaling pathway to regulate p53 protein level. Here, we characterized that RPS2 interacts with MDM2 through the RING finger domain of MDM2. RPS2 is ubiquitinated by MDM2 and the ubiquitinated status of RPS2 regulates the stability of p53, which is activated in response to cellular stresses such as DNA damage, oxidative stress, and especially ribosomal stress. In addition, p53 is not induced in RPS2 knockdown even in the ribosomal stressed condition, indicating that RPS2 is essential for the stabilization of p53. Collectively, our data suggest that RPS2 plays a critical role in the regulation of p53 signaling including the ribosomal stress response.

MiR-195 and miR-497 suppress tumorigenesis in lung cancer by inhibiting SMURF2-induced TGF-β receptor I ubiquitination

SMURF2 is a member of the HECT family of E3 ubiquitin ligases that have important roles as a negative regulator of transforming growth factor‐β (TGF‐β) signaling through ubiquitin‐mediated degradation of TGF‐β receptor I. However, the regulatory mechanism of SMURF2 is largely unknown. In this study, we identified that micro(mi)R‐195 and miR‐497 putatively target SMURF2 using several target prediction databases. Both miR‐195 and miR‐497 bind to the 3′‐UTR of the SMURF2 mRNA and inhibit SMURF2 expression. Furthermore, miR‐195 and miR‐497 regulate SMURF2‐dependent TβRI ubiquitination and cause the activation of the TGF‐β signaling pathway in lung cancer cells. Upregulation of miR‐195 and miR‐497 significantly reduced cell viability and colony formation through the activation of TGF‐β signaling. Interestingly, miR‐195 and miR‐497 also reduced the invasion ability of lung cancer cells when cells were treated with TGF‐β1. Subsequent in vivo studies in xenograft nude mice model revealed that miR‐195 and miR‐497 repress tumor growth. These findings demonstrate that miR‐195 and miR‐497 act as a tumor suppressor by suppressing ubiquitination‐mediated degradation of TGF‐β receptors through SMURF2, and suggest that miR‐195 and miR‐497 are potential therapeutic targets for lung cancer.

Phosphorylation of USP15 and USP4 Regulates Localization and Spliceosomal Deubiquitination

Deubiquitinating enzymes have key roles in diverse cellular processes whose enzymatic activities are regulated by different mechanisms including post-translational modification. Here, we show that USP15 is phosphorylated, and its localization and activity are dependent on the phosphorylation status. Nuclear-cytoplasmic fractionation and mass spectrometric analysis revealed that Thr149 and Thr219 of human USP15, which is conserved among different species, are phosphorylated in the cytoplasm. The phosphorylation status of USP15 at these two positions alters the interaction with its partner protein SART3, consequently leading to its nuclear localization and deubiquitinating activity toward the substrate PRP31. Treatment of cells with purvalanol A, a cyclin-dependent kinase inhibitor, results in nuclear translocation of USP15. USP4, another deubiquitinating enzyme with a high sequence homology and domain structure as USP15, also showed purvalanol A-dependent changes in activity and localization. Collectively, our data suggest that modifications of USP15 and USP4 by phosphorylation are important for the regulation of their localization required for cellular function in the spliceosome.

A carrier-free multiplexed gene editing system applicable for suspension cells

Genetically engineered cells via CRISPR/Cas9 system can serve as powerful sources for cancer immunotherapeutic applications. Furthermore, multiple genetic alterations are necessary to overcome tumor-induced immune-suppressive mechanisms. However, one of the major obstacles is the technical difficulty with efficient multiple gene manipulation of suspension cells due to the low transfection efficacy. Herein, we established a carrier-free multiplexed gene editing platform in a simplified method, which can enhance the function of cytotoxic CD8⁺ T cells by modulating suspension cancer cells. Our multiple Cas9 ribonucleoproteins (RNPs) enable simultaneous disruption of two programmed cell death 1 (PD-1) ligands, functioning as negative regulators in the immune system, by accessing engineered Cas9 proteins with abilities of complexation and cellular penetration. In addition, combination with electroporation enhanced multiple gene editing efficacy, compared with that by treatment of multiple Cas9 RNPs alone. This procedure resulted in high gene editing at multiple loci of suspension cells. The treatment of multiple Cas9 RNPs targeting both ligands strongly improved Th1-type cytokine production of cytotoxic CD8⁺ T cells, resulting in synergistic cytotoxic effects against cancer. Simultaneous suppression of PD-L1 and PD-L2 on cancer cells via our developed editing system allows effective anti-tumor immunity. Furthermore, the treatment of multiple Cas9 RNPs targeting PD-L1, PD-L2, and TIM-3 had approximately 70-90% deletion efficacy. Thus, our multiplexed gene editing strategy endows potential clinical utilities in cancer immunotherapy.

Solitary Parathyroid Adenoma Localization in Technetium Tc99m Sestamibi SPECT and Multiphase Multidetector 4D CT

BACKGROUND AND PURPOSE

Minimally invasive parathyroid surgery relies critically on image guidance, but data comparing the efficacy of various imaging modalities are scarce. Our aim was to perform a blinded comparison of the localizing capability of technetium Tc99m sestamibi SPECT, multiphase multidetector 4D CT, and the combination of these 2 modalities (technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT).

MATERIALS AND METHODS

We reviewed the records of 31 (6 men, 25 women; median age, 56 years) consecutive patients diagnosed with biochemically confirmed primary hyperparathyroidism between November 2009 and March 2010 who underwent preoperative technetium Tc99m sestamibi SPECT and multiphase multidetector 4D CT performed on the same scanner with pathologic confirmation by resection of a single parathyroid adenoma. Accuracy was determined separately for localization to the correct side and quadrant using surgical localization as the standard of reference.

RESULTS

Surgical resection identified 14 left and 17 right parathyroid adenomas and 2 left inferior, 12 left superior, 11 right inferior, and 6 right superior parathyroid adenomas. For left/right localization, technetium Tc99m sestamibi SPECT achieved an accuracy of 93.5% (29 of 31), multiphase multidetector 4D CT achieved 96.8% accuracy (30 of 31), and technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT achieved 96.8% accuracy (30 of 31). For quadrant localization, technetium Tc99m sestamibi SPECT accuracy was 67.7% (21 of 31), multiphase multidetector 4D CT accuracy was 87.1% (27 of 31), and technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT accuracy was 93.5% (29 of 31). Reader diagnostic confidence was consistently ranked lowest for technetium Tc99m sestamibi SPECT and highest for technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT.

CONCLUSIONS

For left/right localization of parathyroid adenomas, all modalities performed equivalently. For quadrant localization, technetium Tc99m sestamibi SPECT + multiphase multidetector 4D CT is superior to technetium Tc99m sestamibi SPECT.

Simple in Vivo Gene Editing via Direct Self-Assembly of Cas9 Ribonucleoprotein Complexes for Cancer Treatment

Cas9 ribonucleoprotein (RNP)-mediated delivery has emerged as an ideal approach for in vivo applications. However, the delivery of Cas9 RNPs requires electroporation or lipid- or cationic-reagent-mediated transfection. Here, we developed a carrier-free Cas9 RNP delivery system for robust gene editing in vivo. For simultaneous delivery of Cas9 and a guide RNA into target cells without the aid of any transfection reagents, we established a multifunctional Cas9 fusion protein (Cas9-LMWP) that forms a ternary complex with synthetic crRNA:tracrRNA hybrids in a simple procedure. Cas9-LMWP carrying both a nuclear localization sequence and a low-molecular-weight protamine (LMWP) enables the direct self-assembly of a Cas9:crRNA:tracrRNA ternary complex (a ternary Cas9 RNP) and allows for the delivery of the ternary Cas9 RNPs into the recipient cells, owing to its intrinsic cellular and nuclear translocation ability with low immunogenicity. To demonstrate the potential of this system, we showed extensive synergistic anti-KRAS therapy (CI value: 0.34) via in vitro and in vivo editing of the KRAS gene by the direct delivery of multifunctional Cas9 RNPs in lung cancer. Thus, our carrier-free Cas9 RNP delivery system could be an innovative platform that might serve as an alternative to conventional transfection reagents for simple gene editing and high-throughput genetic screening.

Small molecule activator of Nm23/NDPK as an inhibitor of metastasis

Nm23-H1/NDPK-A is a tumor metastasis suppressor having NDP kinase (NDPK) activity. Nm23-H1 is positively associated with prolonged disease-free survival and good prognosis of cancer patients. Approaches to increasing the cellular levels of Nm23-H1 therefore have significance in the therapy of metastatic cancers. We found a small molecule, (±)-trans-3-(3,4-dimethoxyphenyl)-4-[(E)-3,4-dimethoxystyryl]cyclohex-1-ene, that activates Nm23, hereafter called NMac1. NMac1 directly binds to Nm23-H1 and increases its NDPK activity. Employing various NMac1 derivatives and hydrogen/deuterium mass spectrometry (HDX-MS), we identified the pharmacophore and mode of action of NMac1. We found that NMac1 binds to the C-terminal of Nm23-H1 and induces the NDPK activation through its allosteric conformational changes. NMac1-treated MDA-MB-231 breast cancer cells showed dramatic changes in morphology and actin-cytoskeletal organization following inhibition of Rac1 activation. NMac1 also suppressed invasion and migration in vitro, and metastasis in vivo, in a breast cancer mouse model. NMac1 as an activator of NDPK has potential as an anti-metastatic agent.

Phosphorylation of human enhancer filamentation 1 (HEF1) stimulates interaction with Polo-like kinase 1 leading to HEF1 localization to focal adhesions

Elevated expression of human enhancer filamentation 1 (HEF1; also known as NEDD9 or Cas-L) is an essential stimulus for the metastatic process of various solid tumors. This process requires HEF1 localization to focal adhesions (FAs). Although the association of HEF1 with FAs is considered to play a role in cancer cell migration, the mechanism targeting HEF1 to FAs remains unclear. Moreover, up-regulation of Polo-like kinase 1 (Plk1) positively correlates with human cancer metastasis, yet how Plk1 deregulation promotes metastasis remains elusive. Here, we report that casein kinase 1δ (CK1δ) phosphorylates HEF1 at Ser-780 and Thr-804 and that these phosphorylation events promote a physical interaction between Plk1 and HEF1. We found that this interaction is critical for HEF1 translocation to FAs and for inducing migration of HeLa cells. Plk1-docking phosphoepitopes were mapped/confirmed in HEF1 by various methods, including X-ray crystallography, and mutated for functional analysis in HeLa cells. In summary, our results reveal the role of a phosphorylation-dependent HEF1-Plk1 complex in HEF1 translocation to FAs to induce cell migration. Our findings provide critical mechanistic insights into the HEF1-Plk1 complex-dependent localization of HEF1 to FAs underlying the metastatic process and may therefore contribute to the development of new cancer therapies.

Unique binding mode of Evogliptin with human dipeptidyl peptidase IV

Evogliptin ((R)-4-((R)-3-amino-4-(2,4,5-trifluorophenyl)butanoyl)-3-(tert-butoxymethyl) piperazine-2-one)) is a highly potent selective inhibitor of dipeptidyl peptidase IV (DPP4) that was approved for the treatment of type 2 diabetes in South Korea. In this study, we report the crystal structures of Evogliptin, DA-12166, and DA-12228 (S,R diastereomer of Evogliptin) complexed to human DPP4. Analysis of both the structures and inhibitory activities suggests that the binding of the trifluorophenyl moiety in the S₁ pocket and the piperazine-2-one moiety have hydrophobic interactions with Phe357 in the S₂ extensive subsite, and that the multiple hydrogen bonds made by the (R)-β-amine group in the S₂ pocket and the contacts made by the (R)-tert-butyl group with Arg125 contribute to the high potency observed for Evogliptin.

USP15 regulates dynamic protein-protein interactions of the spliceosome through deubiquitination of PRP31

Post-translational modifications contribute to the spliceosome dynamics by facilitating the physical rearrangements of the spliceosome. Here, we report USP15, a deubiquitinating enzyme, as a regulator of protein-protein interactions for the spliceosome dynamics. We show that PRP31, a component of U4 snRNP, is modified with K63-linked ubiquitin chains by the PRP19 complex and deubiquitinated by USP15 and its substrate targeting factor SART3. USP15SART3 makes a complex with USP4 and this ternary complex serves as a platform to deubiquitinate PRP31 and PRP3. The ubiquitination and deubiquitination status of PRP31 regulates its interaction with the U5 snRNP component PRP8, which is required for the efficient splicing of chromosome segregation related genes, probably by stabilizing the U4/U6.U5 tri-snRNP complex. Collectively, our data suggest that USP15 plays a key role in the regulation of dynamic protein-protein interactions of the spliceosome.

Structural and biochemical characterization of FabK from Thermotoga maritima

TM0800 from Thermotoga maritima is one of the hypothetical proteins with unknown function. The crystal structure determined at 2.3 Å resolution reveals a two domain structure: the N-terminal domain forming a barrel and the C-terminal forming a lid. One FMN is bound between the two domains with the phosphate making intricate hydrogen bonds with protein and three tightly bound water molecules, and the isoalloxazine ring packed against the side chains of Met22 and Met276. The structure is almost identical to that of FabK (enoyl-acyl carrier protein (ACP) reductase, ENR II), a key enzyme in bacterial type II fatty-acid biosynthesis that catalyzes the final step in each elongation cycle; and the enzymatic activity confirms that TM0800 is an ENR. Enzymatic activity was almost completely abolished when the helices connecting the barrel and the lid were deleted. Also, the Met276Ala and Ser280Ala mutants showed a significant reduction in enzymatic activity. The crystal structure of Met276Ala mutant at 1.9 Å resolution showed an absence of FMN suggesting that FMN plays a role in catalysis, and Met276 is important in positioning FMN. TmFabK exists as a dimer in both solution and crystal. Together this study provides molecular basis for the catalytic activity of FabK.

Proteasome inhibitors attenuated cholesterol-induced cardiac hypertrophy in H9c2 cells

The Ubiquitin proteasome system (UPS) plays roles in protein degradation, cell cycle control, and growth and inflammatory cell signaling. Dysfunction of UPS in cardiac diseases has been seen in many studies. Cholesterol acts as an inducer of cardiac hypertrophy. In this study, the effect of proteasome inhibitors on the cholesterol-induced hypertrophic growth in H9c2 cells is examined in order to observe whether UPS is involved in cardiac hypertrophy. The treatment of proteasome inhibitors MG132 and Bortezomib markedly reduced cellular surface area and mRNA expression of β-MHC in cholesterol-induced cardiac hypertrophy. In addition, activated AKT and ERK were significantly attenuated by MG132 and Bortezomib in cholesterol-induced cardiac hypertrophy. We demonstrated that cholesterol-induced cardiac hypertrophy was suppressed by proteasome inhibitors. Thus, regulatory mechanism of cholesterol-induced cardiac hypertrophy by proteasome inhibitors may provide a new therapeutic strategy to prevent the progression of heart failure. [BMB Reports 2016; 49(5): 270-275]

[IDENTIFICATION OF CAUSATIVE AGENTS OF GLANDERS AND MELIOIDOSIS BASED ON PRINCIPLES OF POLYPHASE TAXONOMIC APPROACH]

AIM

Determine an optimal set of the most effective methods of identification and intraspecies typing ofcausative agents ofglanders and melioidosis. Materials andmethods. Bacteriologic, immunochemical, molecular-genetic methods were used.

RESULTS

A possibility to identify collection strains of pathogenic and closely related Burkholderia in semiautomatic systems is studied. Means of detection of informative variable genome segments ofthe specified microorganisms were developed, methods of their genetic typing were selected. Effectiveness of application of precipitating mAbs for differentiation of Burkholderia was established. Data on diagnostic possibilities of immunoglobulins fluorescing based on monoclonal antibodies of various etiotropic directionality for detection and identification of B. mallei and B. pseudomallei are generalized. Experimental series of amplification test-systems for identification of glanders and melioidosis causative agents in real-time PCR format are created.

CONCLUSION

A number of methods for identification and typing of glanders and melioidosis causative agents is proposed.

Structural Basis for the Interaction between the IUS-SPRY Domain of RanBPM and DDX-4 in Germ Cell Development

RanBPM and RanBP10 are non-canonical members of the Ran binding protein family that lack the Ran binding domain and do not associate with Ran GTPase in vivo. Rather, they have been shown to be scaffolding proteins that are important for a variety of cellular processes, and both of these proteins contain a SPRY domain, which has been implicated in mediating protein-protein interactions with a variety of targets including the DEAD-box containing ATP-dependent RNA helicase (DDX-4). In this study, we have determined the crystal structures of the SPIa and the ryanodine receptor domain and of approximately 70 upstream residues (immediate upstream to SPRY motif) of both RanBPM and RanBP10. They are almost identical, composed of a β-sandwich fold with a set of two helices on each side located at the edge of the sheets. A unique shallow binding surface is formed by highly conserved loops on the surface of the β-sheet with two aspartates on one end, a positive patch on the opposite end, and a tryptophan lining at the bottom of the surface. The 20-mer peptide (residues 228-247) of human DDX-4, an ATP-dependent RNA helicase known to regulate germ cell development, binds to this surface with a K_D of ~13μM. The crystal structure of the peptide complex and the mutagenesis studies elucidate how RanBPM can recognize its interaction partners to function in gametogenesis.

Crystal structures of human peroxiredoxin 6 in different oxidation states

Peroxiredoxins (Prxs) are a family of antioxidant enzymes found ubiquitously. Prxs function not only as H2O2 scavengers but also as highly sensitive H2O2 sensors and signal transducers. Since reactive oxygen species are involved in many cellular metabolic and signaling processes, Prxs play important roles in various diseases. Prxs can be hyperoxidized to the sulfinic acid (SO2H) or sulfonic acid (SO3H) forms in the presence of high concentrations of H2O2. It is known that oligomerization of Prx is changed accompanying oxidation states, and linked to the function. Among the six Prxs in mammals, Prx6 is the only 1-Cys Prx. It is found in all organs in humans, unlike some 2-Cys Prxs, and is present in all species from bacteria to humans. In addition, Prx6 has Ca(2+)-independent phospholipase A2 (PLA2) activity. Thus far only the crystal structure of Prx in the oxidized state has been reported. In this study, we present the crystal structures of human Prx6 in the reduced (SH) and the sulfinic acid (SO2H) forms.

Structural basis for recruiting and shuttling of the spliceosomal deubiquitinase USP4 by SART3

Squamous cell carcinoma antigen recognized by T-cells 3 (SART3) is a U4/U6 recycling factor as well as a targeting factor of USP4 and USP15. However, the details of how SART3 recognizes these deubiquitinases and how they get subsequently translocated into the nucleus are not known. Here, we present the crystal structures of the SART3 half-a-tetratricopeptide (HAT) repeat domain alone and in complex with the domain present in ubiquitin-specific protease (DUSP)-ubiquitin-like (UBL) domains of ubiquitin specific protease 4 (USP4). The 12 HAT repeats of SART3 are in two sub-domains (HAT-N and HAT-C) forming a dimer through HAT-C. USP4 binds SART3 at the opposite surface of the HAT-C dimer interface utilizing the β-structured linker between the DUSP and the UBL domains. The binding affinities of USP4 and USP15 to SART3 are 0.9 μM and 0.2 μM, respectively. The complex structure of SART3 nuclear localization signal (NLS) and importin-α reveals bipartite binding, and removal of SART3 NLS prevents the entry of USP4 (and USP15) into the nucleus and abrogates the subsequent deubiquitinase activity of USP4.

A Food Effect Study of an Oral Thrombin Inhibitor and Prodrug Approach To Mitigate It

LB30870, a new direct thrombin inhibitor, showed 80% reduction in oral bioavailability in fed state. The present study aims to propose trypsin binding as a mechanism for such negative food effect and demonstrate a prodrug approach to mitigate food effect. Effect of food composition on fed state oral bioavailability of LB30870 was studied in dogs. Various prodrugs were synthesized, and their solubility, permeability, and trypsin binding affinity were measured. LB30870 and prodrugs were subject to cocrystallization with trypsin, and the X-ray structures of cocrystals were determined. Food effect was studied in dogs for selected prodrugs. Protein or lipid meal appeared to affect oral bioavailability of LB30870 in dogs more than carbohydrate meal. Blocking both carboxyl and amidine groups of LB30870 resulted in trypsin Ki values orders of magnitude higher than that of LB30870. Prodrugs belonged to either Biopharmaceutical Classification System I, II, or III. X-ray crystallography revealed that prodrugs did not bind to trypsin, but instead their hydrolysis product at the amidine blocking group formed cocrystal with trypsin. A prodrug with significantly less food effect than LB30870 was identified. Binding of prodrugs to food components such as dietary fiber appeared to counteract the positive effect brought with the prodrug approach. Further formulation research is warranted to enhance the oral bioavailability of prodrugs. In conclusion, this study is the first to demonstrate that the negative food effect of LB30870 can be attributed to trypsin binding. Trypsin binding study is proposed as a screening tool during lead optimization to minimize food effect.

Structure of mouse muskelin discoidin domain and biochemical characterization of its self-association

Muskelin is an intracellular kelch-repeat protein comprised of discoidin, LisH, CTLH and kelch-repeat domains. It is involved in cell adhesion and the regulation of cytoskeleton dynamics as well as being a component of a putative E3 ligase complex. Here, the first crystal structure of mouse muskelin discoidin domain (MK-DD) is reported at 1.55 Å resolution, which reveals a distorted eight-stranded β-barrel with two short α-helices at one end of the barrel. Interestingly, the N- and C-termini are not linked by the disulfide bonds found in other eukaryotic discoidin structures. A highly conserved MIND motif appears to be the determinant for MK-DD specific interaction together with the spike loops. Analysis of interdomain interaction shows that MK-DD binds the kelch-repeat domain directly and that this interaction depends on the presence of the LisH domain.

Quantitative analysis of a ubiquitin-dependent substrate using capillary electrophoresis with dual laser-induced fluorescence

Protein degradation by the ubiquitin-proteasome system (UPS) affects many biological processes. Inhibition of the proteasome has emerged as a potential therapeutic target for cancer treatment. In this study, we developed a method for monitoring the degradation and accumulation of UPS-dependent substrates in cells using CE with dual LIF. We used a green fluorescent protein (GFP)-fusion of the ubiquitin substrate ribophorin 1 (GFP-RPN1) along with red fluorescent protein (RFP) as an internal control to normalize transfection efficiency. Determination of GFP-RPN1 and RFP in cell lysates were performed in an untreated capillary (75 μm × 50 cm) and 100 mM Tris-CHES buffer (pH 9.0) containing 10 mM SDS. GFP-RPN1 and RFP fluorescence were detected at excitation wavelengths of 488 and 635 nm, and emission wavelengths of 520 and 675 nm, respectively, without any interference or crosstalk. The intensity of GFP-RPN1 fluorescence was normalized to that of RFP. Additionally, the proposed approach was used successfully to detect the degradation of GFP-RPN1 and evaluate proteasome inhibitors. These results show that the developed method is effective and promising for rapid and quantitative monitoring of UPS-dependent substrates compared to the current common methods, such as immunoblotting and pulse chase assays.

Crystallization and preliminary X-ray crystallographic analysis of the complex between the N-D1 domain of VCP from Homo sapiens and the N domain of OTU1 from Saccharomyces cerevisiae

VCP (valosin-containing protein; also known as p97) plays important roles in many biological processes including the ERAD (endoplasmic reticulum-associated degradation) pathway and its function is governed by binding partners. OTU1 (ovarian tumour domain-containing protein 1) is a recently discovered deubiquitinating enzyme that interacts directly with VCP in the ERAD pathway. In order to understand the interactions between the two proteins, the N-D1 domain of VCP and the UBXL domain of OTU1 were cloned, overexpressed, purified and crystallized. The crystals of the complex diffracted to 3.25 Å resolution and belonged to space group P21, with unit-cell parameters a = 165.45, b = 176.73, c = 165.59 Å, β = 120.095°. There are two molecules of the complex in the asymmetric unit with a Matthews coefficient of 2.62 Å(3) Da(-1) and a solvent content of 53%.

Structural basis for ovarian tumor domain-containing protein 1 (OTU1) binding to p97/valosin-containing protein (VCP)

Valosin-containing protein (VCP), also known as p97, is an AAA(+) ATPase that plays an essential role in a broad array of cellular processes including the endoplasmic reticulum-associated degradation (ERAD) pathway. Recently, ERAD-specific deubiquitinating enzymes have been reported to be physically associated with VCP, although the exact mechanism is not yet clear. Among these enzymes is ovarian tumor domain-containing protein 1 (OTU1). Here, we report the structural basis for interaction between VCP and OTU1. The crystal structure of the ubiquitin regulatory X-like (UBXL) domain of OTU1 (UBXLOTU1) complexed to the N-terminal domain of VCP (NVCP) at 1.8-Å resolution reveals that UBXLOTU1 adopts a ubiquitin-like fold and binds at the interface of two subdomains of NVCP using the (39)GYPP(42) loop of UBXLOTU1 with the two prolines in cis- and trans-configurations, respectively. A mutagenesis study shows that this loop is not only critical for the interaction with VCP but also for its role in the ERAD pathway. Negative staining EM shows that one molecule of OTU1 binds to one VCP hexamer, and isothermal titration calorimetry suggests that the two proteins bind with a KD of 0.71 μM. Analytical size exclusion chromatography and isothermal titration calorimetry demonstrates that OTU1 can bind VCP in both the presence and absence of a heterodimer formed by ubiquitin fusion degradation protein 1 and nuclear localization protein 4.

Complex of Fas-associated factor 1 (FAF1) with valosin-containing protein (VCP)-Npl4-Ufd1 and polyubiquitinated proteins promotes endoplasmic reticulum-associated degradation (ERAD)

Fas-associated factor 1 (FAF1) is a ubiquitin receptor containing multiple ubiquitin-related domains including ubiquitin-associated (UBA), ubiquitin-like (UBL) 1, UBL2, and ubiquitin regulatory X (UBX). We previously showed that N-terminal UBA domain recognizes Lys(48)-ubiquitin linkage to recruit polyubiquitinated proteins and that a C-terminal UBX domain interacts with valosin-containing protein (VCP). This study shows that FAF1 interacts only with VCP complexed with Npl4-Ufd1 heterodimer, a requirement for the recruitment of polyubiquitinated proteins to UBA domain. Intriguingly, VCP association to C-terminal UBX domain regulates ubiquitin binding to N-terminal UBA domain without direct interaction between UBA and UBX domains. These interactions are well characterized by structural and biochemical analysis. VCP-Npl4-Ufd1 complex is known as the machinery required for endoplasmic reticulum-associated degradation. We demonstrate here that FAF1 binds to VCP-Npl4-Ufd1 complex via UBX domain and polyubiquitinated proteins via UBA domain to promote endoplasmic reticulum-associated degradation.

Novel β-structure of YLR301w from Saccharomyces cerevisiae

When the Z-type variant of human α(1)-antitrypsin was overexpressed in Saccharomyces cerevisiae, proteomics analysis identified YLR301w as one of the up-regulated proteins. YLR301w is a 27.5 kDa protein with no sequence homology to any known protein and has been reported to interact with Sec72 and Hrr25. The crystal structure of S. cerevisiae YLR301w has been determined at 2.3 Å resolution, revealing a novel β-structure. It consists of an N-terminal ten-stranded β-barrel with two short α-helices connected by a 23-residue linker to a seven-stranded half-barrel with two short helices at the C-terminus. The N-terminal barrel has a highly conserved hydrophobic channel that can bind hydrophobic molecules such as PEG. It forms a homodimer both in the crystal and in solution. YLR301w binds Sec72 with a K(d) of 6.2 µM, but the biological significance of this binding requires further investigation.

Structure of ubiquitin-fold modifier 1-specific protease UfSP2

Ubiquitin-fold modifier 1 (Ufm1)-specific protease 2 (UfSP2) is a cysteine protease that is responsible for the release of Ufm1 from Ufm1-conjugated cellular proteins, as well as for the generation of mature Ufm1 from its precursor. The 2.6 Å resolution crystal structure of mouse UfSP2 reveals that it is composed of two domains. The C-terminal catalytic domain is similar to UfSP1 with Cys(294), Asp(418), His(420), Tyr(282), and a regulatory loop participating in catalysis. The novel N-terminal domain shows a unique structure and plays a role in the recognition of its cellular substrate C20orf116 and thus in the recruitment of UfSP2 to the endoplasmic reticulum, where C20orf116 predominantly localizes. Mutagenesis studies were carried out to provide the structural basis for understanding the loss of catalytic activity observed in a recently identified UfSP2 mutation that is associated with an autosomal dominant form of hip dysplasia.

Cloning, purification, crystallization and preliminary X-ray crystallographic analysis of MCAT from Staphylococcus aureus

Malonyl-CoA:acyl-carrier protein transacylase (MCAT), encoded by the fabd gene, is a key enzyme in type II fatty-acid biosynthesis. It is responsible for transferring the malonyl group from malonyl-CoA to the holo acyl-carrier protein (ACP). Since the type II system differs from the type I system that mammals use, it has received enormous attention as a possible antibiotic target. In particular, only a single isoform of MCAT has been reported and a continuous coupled enzyme assay has been developed. MCAT from Staphylococcus aureus was overexpressed in Escherichia coli and the protein was purified and crystallized. Diffraction data were collected to 1.2 A resolution. The crystals belonged to space group P2(1), with unit-cell parameters a = 41.608, b = 86.717, c = 43.163 A, alpha = gamma = 90, beta = 106.330 degrees . The asymmetric unit contains one SaMCAT molecule.

Crystallization and preliminary X-ray crystallographic analysis of the probable tRNA-modification GTPase (TrmE) from Staphylococcus aureus

Probable tRNA-modification GTPase (TrmE) is a guanine nucleotide-binding protein that is conserved between bacteria and humans. GTPase hydrolyzes GTP and plays a pivotal role in signalling pathways. In this study, TrmE from Staphylococcus aureus was overexpressed in Escherichia coli. The enzyme was found to crystallize at 295 K when ammonium sulfate was used as a precipitant. X-ray diffraction data were collected to 2.9 A resolution from the crystallized enzyme using synchrotron radiation. The crystal was found to belong to the cubic space group I23, with unit-cell parameters a = b = c = 229.47 A, alpha = beta = gamma = 90 degrees . The crystal is likely to contain four monomers in the asymmetric unit, with a corresponding V(M) of 2.4 A(3) Da(-1) and a solvent content of 50%.