Determination of the three-dimensional structure of bacteriophage Mu(-) tail fiber and its characterization.

Bacteriophage Mu is a temperate phage known to infect various species of Enterobacteria, playing a role in bacterial mutation induction and horizontal gene transfer. The phage possesses two types of tail fibers important for host recognition, which enable it to expand its range of hosts. The alternate tail fibers are formed through the action of genes 49-50 or 52-51, allowing the Mu phage to recognize different surfaces of host cells. In a previous study, we presented the X-ray crystal structure of the C-terminal lipopolysaccharide (LPS)-binding domain of gene product (gp) 49, one of the subunits comprising the Mu tail fiber. In this study, we have determined the structure of the alternative tail fiber subunit, gp52, and compared it with other tail fibers. The results revealed that Mu phage employs different structural motifs for two individual tail fibers for recognizing different hosts.

Comparative analysis of two Caenorhabditis elegans kinesins KLP-6 and UNC-104 reveals a common and distinct activation mechanism in kinesin-3.

Kinesin-3 is a family of microtubule-dependent motor proteins that transport various cargos within the cell. However, the mechanism underlying kinesin-3 activations remains largely elusive. In this study, we compared the biochemical properties of two Caenorhabditis elegans kinesin-3 family proteins, KLP-6 and UNC-104. Both KLP-6 and UNC-104 are predominantly monomeric in solution. As previously shown for UNC-104, non-processive KLP-6 monomer is converted to a processive motor when artificially dimerized. We present evidence that releasing the autoinhibition is sufficient to trigger dimerization of monomeric UNC-104 at nanomolar concentrations, which results in processive movement of UNC-104 on microtubules, although it has long been thought that enrichment in the phospholipid microdomain on cargo vesicles is required for the dimerization and processive movement of UNC-104. In contrast, KLP-6 remains to be a non-processive monomer even when its autoinhibition is unlocked, suggesting a requirement of other factors for full activation. By examining the differences between KLP-6 and UNC-104, we identified a coiled-coil domain called coiled-coil 2 (CC2) that is required for the efficient dimerization and processive movement of UNC-104. Our results suggest a common activation mechanism for kinesin-3 family members, while also highlighting their diversification.

Effect of radical trachelectomy on ovarian reserve: A single-institute prospective study.

AIM: Reduced responses to controlled ovarian stimulation (COS) after radical trachelectomy (RT) have been previously reported. We aimed to assess the effect of RT on ovarian reserve by measuring anti-Müllerian hormone (AMH) levels before and after the procedure in this prospective study. METHODS: We included 12 patients who underwent RT between September 2019 and December 2021 in this study. Serum AMH levels were measured preoperatively, 1 month postoperatively, and 6 months postoperatively. Differences in the AMH levels were assessed using a paired t-test. RESULTS: The median age of the patients was 30.6 years, and the median follow-up time was 30.1 months. AMH levels at 1 and 6 months postoperatively did not show a consistent trend. At 1 month postoperatively, the average AMH level decreased insignificantly but returned to preoperative levels at 6 months. The differences in AMH levels before and after RT were insignificant. CONCLUSION: Our findings indicate that RT did not affect ovarian reserve as measured by AMH levels. However, the relationship between unchanged ovarian reserve and reduced response to COS remains unclear. Further research with larger sample sizes and additional measures of ovarian function is needed to corroborate these results and investigate the long-term effects of RT on ovarian reserve. Understanding these mechanisms will help guide surgical practices and provide patients with valuable information about their reproductive outcomes after RT.

Impairment of Social-Related Quality of Life in COVID-19 Pneumonia Survivors: A Prospective Longitudinal Study.

The post-acute sequelae of SARS-CoV-2 (PASC) pose a threat to patients' health-related quality of life (HRQOL). Here, the impact of COVID-19 on HRQOL and the clinical factors associated with impaired HRQOL were examined. Discharged COVID-19 patients were assessed at 3 and 6 months after disease onset. The patients completed a medical examination and the SF-36 questionnaire at these two time points and underwent pulmonary function testing at 6 months after disease onset. All had undergone computed tomography (CT) imaging upon hospital admission. Of the 74 included patients, 38% reported respiratory symptoms at 3 months, and 26% reported respiratory symptoms at 6 months after disease onset. The aggregated SF-36 scores declined in the role/social component summary (RCS), a category related to social activity. Patients with lower RCS tended to have respiratory sequelae or a relatively lower forced vital capacity. The CT score that reflected the extent of COVID-19 pneumonia was inversely correlated with the RCS score (3 months, p = 0.0024; 6 months, p = 0.0464). A high CT score (≥10 points) predicted a low RCS score at 6 months (p = 0.013). This study highlights the impairment of RCS and its associations with respiratory sequelae. The study also emphasizes the importance of radiological findings in predicting long-term HRQOL outcomes after COVID-19.

Reliability of the respiratory rate and oxygenation index for successful high-flow nasal cannula support in coronavirus disease pneumonia: a retrospective cohort study.

BACKGROUND: High-flow nasal cannula (HFNC) therapy is an important non-invasive respiratory support in acute respiratory failure, including coronavirus disease (COVID-19) pneumonia. Although the respiratory rate and oxygenation (ROX) index is a simple and useful predictor for HFNC failure and mortality, there is limited evidence for its use in patients with COVID-19 pneumonia. We aimed to evaluate the ROX index as a predictor for HFNC failure in patients with COVID-19 pneumonia. We also evaluated the ROX index as a predictor for 28-day mortality. METHODS: In this single-center, retrospective, cohort study, 248 patients older than 18 years of age with COVID-19 pneumonia received HFNC therapy for acute respiratory failure. The ROX index was evaluated within 4 h from the start of HFNC therapy. Past medical history, laboratory data, and the ROX index were evaluated as predictors for HFNC failure and 28-day mortality. RESULTS: The ROX index < 4.88 showed a significantly high risk ratio for HFNC failure (2.13 [95% confidence interval [CI]: 1.47 - 3.08], p < 0.001). The ROX index < 4.88 was significantly associated with 28-day mortality (p = 0.049) in patients with COVID-19 pneumonia receiving HFNC therapy. Age, chronic hypertension, high lactate dehydrogenase level, and low ROX index showed significantly high risk ratio for HFNC failure. C-reactive protein level and low ROX index were predictors of 28-day morality. CONCLUSION: The ROX index is a useful predictor for HFNC success and 28-day mortality in patients with COVID-19 pneumonia receiving HFNC therapy. TRIAL REGISTRATION: An independent ethics committee approved the study (Research Ethics Review Committee of Kobe City Medical Center General Hospital [number: zn220303; date: February 21, 2022]), which was performed in accordance with the Declaration of Helsinki, Guidelines for Good Clinical Practice.

Development of a new HISCL automated CXCL9 immunoassay.

C-X-C motif chemokine ligand 9 (CXCL9), a candidate biomarker, reflects type 1 (T1) inflammation pathology. Here, we report the analytical performance and clinical characteristics of a new CXCL9 reagent for a fully automated immunoassay device. We evaluated the limits of blank, detection, and quantitation (LoQ) along with other efficacy parameters, and the ability of the assay to report patient health, COVID-19 status, and the presence of asthma and/or interstitial lung diseases (ILDs). The coefficient of variation for 5-day total precision using two instruments was 7% across two controls, serum, and plasma panels. LoQ of 2.2 pg/mL suggested the efficacy of the assay in detecting T1 inflammation in plasma or serum; no cross-reactivity or interference was observed. We identified high serum CXCL9 levels in samples from patients with acute COVID-19 infections (n = 57), chronic bird-related hypersensitivity pneumonitis (n = 61), asthma (n = 194), and ILDs (n = 84) compared to healthy individuals (< 39.0 pg/mL). Furthermore, CXCL9 levels increased with age in asthma patients, and an opposite trend was observed for T2 inflammatory factors. These results suggest the utility of the automated CXCL9 immunoassay for measuring CXCL9 in clinical samples and reflect its role in T1 inflammation.

Longitudinal changes in mental health outcomes after COVID-19 hospitalization: A prospective study.

BACKGROUND: The long-term trends of COVID-19 mental sequelae remain unknown. Thus, this study aimed to survey the one-year temporal trends of PTSD and health-related quality of life of COVID-19 survivors. METHODS: Patients hospitalized with COVID-19 were followed up at three, six, and 12 months after discharge. Patients with COVID-19 who were able to communicate and complete the questionnaires were included in the study. All participants were asked to complete the Medical Outcomes Study 36-Item Short-Form Health (SF-36) survey and the Impact of Event Scale-Revised (IES-R). The cutoff point of 24/25 of IES-R was defined as preliminary PTSD. Patients exhibiting PTSD symptoms at six months or later were regarded as "delayed patients," while those exhibiting PTSD symptoms at all the time points were "persistent patients." RESULTS: Of the 98 patients screened between June and November 2020, 72 participated in the study. A total of 11 (15.3%) had preliminary PTSD at three months, 10 (13.9%) at six months, and 10 (13.9%) at 12 months; delayed and persistent patients were four patients (7.54%) each. Patients with preliminary PTSD had lower mental summary scores in SF-36; 47 (IQR 45, 53) for patients with preliminary PTSD and 60 (49, 64) without preliminary PTSD at three months, 50 (45, 51) and 58 (52, 64) at six months, and 46 (38, 52) and 59 (52, 64) at 12 months. CONCLUSION: Healthcare providers should care about the courses of PTSD in COVID-19 survivors and be aware that patients with PTSD symptoms may have a lower health-related quality of life.

Population pharmacokinetics and exposure-clinical outcome relationship of remdesivir major metabolite GS-441524 in patients with moderate and severe COVID-19.

Although remdesivir, a prodrug of nucleoside analog (GS-441524), has demonstrated clinical benefits in coronavirus disease 2019 (COVID-19) treatment, its pharmacokinetics (PKs) in patients with COVID-19 remain poorly understood. Therefore, in this study, the PKs of remdesivir and its major metabolite, GS-441524, were evaluated using a population PK (PopPK) approach to understand the PK aspect and exposure-clinical outcome relationship. The serum concentrations of remdesivir and GS-441524 (102 points in 39 patients) were measured using liquid chromatography-tandem mass spectrometry. All patients received 200 mg remdesivir on the first day, followed by 100 mg on 2-5 days, except for one patient who discontinued remdesivir on day 4. The median (range) age, body surface area, and estimated glomerular filtration rate (eGFR) were 70 (42-85), 1.74 m2 (1.36-2.03), and 68 mL/min/1.73 m2 (33-113), respectively. A compartment model with first-order elimination combined with remdesivir and GS-441524 was used for nonlinear mixed-effects model analysis. Remdesivir was rapidly eliminated after infusion, whereas GS-441524 was eliminated relatively slowly (half-time = 17.1 h). The estimated apparent clearance (CL) and distribution volume of GS-441524 were 11.0 L/h (intersubject variability [ISV]% = 43.0%) and 271 L (ISV% = 58.1%), respectively. The CL of GS-441524 was significantly related to the eGFR (CL × [eGFR/68]0.745 ). The post hoc area under the curve of GS-441524 was unrelated to the recovery rate or aspartate aminotransferase/alanine aminotransferase elevation. Overall, PopPK analysis showed the rapid elimination of remdesivir in the blood, and GS-441524 accumulation depended on eGFR in patients with COVID-19. However, no relevance of exposure-clinical outcome was not suggestive of the dose adjustment of remdesivir.

Structural insight into the hydrolase and synthase activities of an alkaline α-galactosidase from Arabidopsis from complexes with substrate/product.

The alkaline α-galactosidase AtAkαGal3 from Arabidopsis thaliana catalyzes the hydrolysis of α-D-galactose from galacto-oligosaccharides under alkaline conditions. A phylogenetic analysis based on sequence alignment classifies AtAkαGal3 as more closely related to the raffinose family of oligosaccharide (RFO) synthases than to the acidic α-galactosidases. Here, thin-layer chromatography is used to demonstrate that AtAkαGal3 exhibits a dual function and is capable of synthesizing stachyose using raffinose, instead of galactinol, as the galactose donor. Crystal structures of complexes of AtAkαGal3 and its D383A mutant with various substrates and products, including galactose, galactinol, raffinose, stachyose and sucrose, are reported as the first representative structures of an alkaline α-galactosidase. The structure of AtAkαGal3 comprises three domains: an N-terminal domain with 13 antiparallel ß-strands, a catalytic domain with an (α/ß)8-barrel fold and a C-terminal domain composed of ß-sheets that form two Greek-key motifs. The WW box of the N-terminal domain, which comprises the conserved residues FRSK75XW77W78 in the RFO synthases, contributes Trp77 and Trp78 to the +1 subsite to contribute to the substrate-binding ability together with the (α/ß)8 barrel of the catalytic domain. The C-terminal domain is presumably involved in structural stability. Structures of the D383A mutant in complex with various substrates and products, especially the natural substrate/product stachyose, reveal four complete subsites (-1 to +3) at the catalytic site. A functional loop (residues 329-352) that exists in the alkaline α-galactosidase AtAkαGal3 and possibly in RFO synthases, but not in acidic α-galactosidases, stabilizes the stachyose at the +2 and +3 subsites and extends the catalytic pocket for the transferase mechanism. Considering the similarities in amino-acid sequence, catalytic domain and activity between alkaline α-galactosidases and RFO synthases, the structure of AtAkαGal3 might also serve a model for the study of RFO synthases, structures of which are lacking.

Role of K364 next to the active site cysteine in voltage-dependent phosphatase activity of Ci-VSP.

Voltage-sensing phosphatase (VSP) consists of the voltage sensor domain (VSD) similar to that of voltage-gated ion channels and the cytoplasmic phosphatase region with remarkable similarity to the phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Membrane depolarization activates VSD, leading to dephosphorylation of three species of phosphoinositides (phosphatidylinositol phosphates (PIPs)), PI(3,4,5)P3, PI(4,5)P2, and PI(3,4)P2. VSP dephosphorylates 3- and 5-phosphate of PIPs, unlike PTEN, which shows rigid 3-phosphate specificity. In this study, a bioinformatics search showed that some mammals have VSP orthologs with amino acid diversity in the active center motif, Cx5R, which is highly conserved among protein tyrosine phosphatases and PTEN-related phosphatases; lysine next to the active site cysteine in the Cx5R motif was substituted for methionine in VSP orthologs of Tasmanian devil, koala, and prairie deer mouse, and leucine in opossum. Since lysine at the corresponding site in PTEN is known to be critical for enzyme activities, we attempted to address the significance of amino acid diversity among VSP orthologs at this site. K364 was changed to different amino acids in sea squirt VSP (Ci-VSP), and voltage-dependent phosphatase activity in Xenopus oocyte was studied using fluorescent probes for PI(4,5)P2 and PI(3,4)P2. All mutants retained both 5-phosphatase and 3-phosphatase activity, indicating that lysine at this site is dispensable for 3-phosphatase activity, unlike PTEN. Notably, K364M mutant showed increased activity both of 5-phosphatase and 3-phosphatase compared with the wild type (WT). It also showed slower kinetics of voltage sensor motion. Malachite green assay of K364M mutant did not show significant difference of phosphatase activity from WT, suggesting tighter interaction between substrate binding and voltage sensing. Mutation corresponding to K364M in the zebrafish VSP led to enhanced voltage-dependent dephosphorylation of PI(4,5)P2. Further studies will provide clues to understanding of substrate preference in PIPs phosphatases as well as to customization of a molecular tool.

SARS-CoV-2 ORF8 is a viral cytokine regulating immune responses.

Many patients with severe COVID-19 suffer from pneumonia and the elucidation of the mechanisms underlying the development of this severe condition is important. The in vivo function of the ORF8 protein secreted by SARS-CoV-2 is not well understood. Here, we analyzed the function of ORF8 protein by generating ORF8-knockout SARS-CoV-2 and found that the lung inflammation observed in wild-type SARS-CoV-2-infected hamsters was decreased in ORF8-knockout SARS-CoV-2-infected hamsters. Administration of recombinant ORF8 protein to hamsters also induced lymphocyte infiltration into the lungs. Similar pro-inflammatory cytokine production was observed in primary human monocytes treated with recombinant ORF8 protein. Furthermore, we demonstrated that the serum ORF8 protein levels are well-correlated with clinical markers of inflammation. These results demonstrated that the ORF8 protein is a SARS-CoV-2 viral cytokine involved in the immune dysregulation observed in COVID-19 patients, and that the ORF8 protein could be a novel therapeutic target in severe COVID-19 patients.

Quantitative Evaluation of Changes in Three-Dimensional CT Density Distributions in Pulmonary Alveolar Proteinosis after GM-CSF Inhalation.

BACKGROUND: A previous clinical trial for autoimmune pulmonary alveolar proteinosis (APAP) demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) inhalation reduced the mean density of the lung field on computed tomography (CT) across 18 axial slice planes at a two-dimensional level. In contrast, in this study, we challenged three-dimensional analysis for changes in CT density distribution using the same datasets. METHODS: As a sub-study of the trial, CT data of 31 and 27 patients who received GM-CSF and placebo, respectively, were analyzed. To overcome the difference between various shooting conditions, a newly developed automatic lung field segmentation algorithm was applied to CT data to extract the whole lung volume, and the accuracy of the segmentation was evaluated by five pulmonary physicians independently. For normalization, the percent pixel (PP) in a certain density range was calculated as a percentage of the total number of pixels from -1,000 to 0 HU. RESULTS: The automatically segmented images revealed that the lung field was accurately extracted except for 7 patients with minor deletion or addition. Using the change in PP from baseline to week 25 (ΔPP) as the vertical axis, we created a histogram with 143 HU bins set for each patient. The most significant difference in ΔPP between GM-CSF and placebo groups was observed in two ranges: from -1,000 to -857 and -143 to 0 HU. CONCLUSION: Whole lung extraction followed by density histogram analysis of ΔPP may be an appropriate evaluation method for assessing CT improvement in APAP.

Predictive performance of PD-L1 tumor proportion score for nivolumab response evaluated using archived specimens in patients with non-small cell lung cancer experiencing a postoperative recurrence.

OBJECTIVES: Postoperative recurrence in patients with non-small-cell lung carcinoma (NSCLC) is a major issue for life expectancy. Programmed cell death ligand 1 (PD-L1) expression on tumor cells is important in the prognosis of NSCLC. However, the predictive ability of PD-L1 evaluated with archived surgical specimens for nivolumab treatment have remained unknown. This study was aimed to analyze the predictive ability of the PD-L1 tumor proportion score (TPS) for nivolumab response in patients with NSCLC experiencing a postoperative recurrence using archived surgical specimens. MATERIALS AND METHODS: This retrospective cohort study involved patients with advanced NSCLC (N = 78) treated with nivolumab between April 2016 and September 2018. They were categorized into postoperative recurrence (N = 24) and non-postoperative recurrence (N = 54) groups. The predictive ability of PD-L1 TPS for response to nivolumab treatment in these two groups was determined using receiver operating characteristic (ROC) analysis. Additionally, we evaluated the predictive ability of PD-L1 TPS using rebiopsy specimens collected from the recurrent lesions in six patients of the postoperative recurrence group. RESULTS: PD-L1 TPS exhibited lower predictive performance in the postoperative recurrent group (area under the curve [AUC] = 0.58) compared with that in the non-post operative recurrent group (AUC = 0.81). Furthermore, PD-L1 TPS was significantly increased in rebiopsy specimens. The predictive performance of PD-L1 TPS in these specimens was higher (AUC = 0.90) than that in the archived surgical specimens. CONCLUSION: The study revealed that archived surgical specimens are inadequate for assessing the predictive ability of PD-L1 for nivolumab response, while rebiopsy specimens are adequate.

History of Protein Data Bank Japan: standing at the beginning of the age of structural genomics.

Prof. Haruki Nakamura, who is the former head of Protein Data Bank Japan (PDBj) and an expert in computational biology, retired from Osaka University at the end of March 2018. He founded PDBj at the Institute for Protein Research, together with other faculty members, researchers, engineers, and annotators in 2000, and subsequently established the worldwide Protein Data Bank (wwPDB) in 2003 to manage the core archive of the Protein Data Bank (PDB), collaborating with RCSB-PDB in the USA and PDBe in Europe. As the former head of PDBj and also an expert in structural bioinformatics, he has grown PDBj to become a well-known data center within the structural biology community and developed several related databases, tools and integrated with new technologies, such as the semantic web, as primary services offered by PDBj.

Domain Structure of the Dnmt1, Dnmt3a, and Dnmt3b DNA Methyltransferases.

In mammals, three major DNA methyltransferases, Dnmt1, Dnmt3a, and Dnmt3b, have been identified. Dnmt3a and Dnmt3b are responsible for establishing DNA methylation patterns produced through their de novo-type DNA methylation activity in implantation stage embryos and during germ cell differentiation. Dnmt3-like (Dnmt3l), which is a member of the Dnmt3 family but does not possess DNA methylation activity, was reported to be indispensable for global methylation in germ cells. Once the DNA methylation patterns are established, maintenance-type DNA methyltransferase Dnmt1 faithfully propagates them to the next generation via replication. All Dnmts possess multiple domains. For instance, Dnmt3a and Dnmt3b each contain a Pro-Trp-Trp-Pro (PWWP) domain that recognizes the histone H3K36me2/3 mark, an Atrx-Dnmt3-Dnmt3l (ADD) domain that recognizes unmodified histone H3 tail, and a catalytic domain that methylates CpG sites. Dnmt1 contains an N-terminal independently folded domain (NTD) that interacts with a variety of regulatory factors, a replication foci-targeting sequence (RFTS) domain that recognizes the histone H3K9me3 mark and H3 ubiquitylation, a CXXC domain that recognizes unmodified CpG DNA, two tandem Bromo-Adjacent-homology (BAH1 and BAH2) domains that read the H4K20me3 mark with BAH1, and a catalytic domain that preferentially methylates hemimethylated CpG sites. In this chapter, the structures and functions of these domains are described.

19F chemical library and 19F-NMR for a weakly bound complex structure.

Fragment-based drug discovery (FBDD), which involves small compounds <300 Da, has been recognized as one of the most powerful tools for drug discovery. In FBDD, the affinity of hit compounds tends to be low, and the analysis of protein-compound interactions becomes difficult. In an effort to overcome such difficulty, we developed a 19F-NMR screening method optimizing a 19F chemical library focusing on highly soluble monomeric molecules. Our method was successfully applied to four proteins, including protein kinases and a membrane protein. For FKBP12, hit compounds were carefully validated by protein thermal shift analysis, 1H-15N HSQC NMR spectroscopy, and isothermal titration calorimetry to determine dissociation constants and model complex structures. It should be noted that the 1H and 19F saturation transfer difference experiments were crucial to obtaining highly precise model structures. The combination of 19F-NMR analysis and the optimized 19F chemical library enables the modeling of the complex structure made up of a weak binder and its target protein.

Multifunctional chemical inhibitors of the florigen activation complex discovered by structure-based high-throughput screening.

Structure-based high-throughput screening of chemical compounds that target protein-protein interactions (PPIs) is a promising technology for gaining insight into how plant development is regulated, leading to many potential agricultural applications. At present, there are no examples of using high-throughput screening to identify chemicals that target plant transcriptional complexes, some of which are responsible for regulating multiple physiological functions. Florigen, a protein encoded by FLOWERING LOCUS T (FT), was initially identified as a molecule that promotes flowering and has since been shown to regulate flowering and other developmental phenomena such as tuber formation in potato (Solanum tuberosum). FT functions as a component of the florigen activation complex (FAC) with a 14-3-3 scaffold protein and FD, a bZIP transcription factor that activates downstream gene expression. Although 14-3-3 is an important component of FAC, little is known about the function of the 14-3-3 protein itself. Here, we report the results of a high-throughput in vitro fluorescence resonance energy transfer (FRET) screening of chemical libraries that enabled us to identify small molecules capable of inhibiting FAC formation. These molecules abrogate the in vitro interaction between the 14-3-3 protein and the OsFD1 peptide, a rice (Oryza sativa) FD, by directly binding to the 14-3-3 protein. Treatment with S4, a specific hit molecule, strongly inhibited FAC activity and flowering in duckweed, tuber formation in potato, and branching in rice in a dose-dependent manner. Our results demonstrate that the high-throughput screening approach based on the three-dimensional structure of PPIs is suitable in plants. In this study, we have proposed good candidate compounds for future modification to obtain inhibitors of florigen-dependent processes through inhibition of FAC formation.

Crystal structure of potato 14-3-3 protein St14f revealed the importance of helix I in StFDL1 recognition.

In potato (Solanum tuberosum L.), 14-3-3 protein forms a protein complex with the FLOWERING LOCUS T (FT)-like protein StSP6A and the FD-like protein StFDL1 to activate potato tuber formation. Eleven 14-3-3 isoforms were reported in potato, designated as St14a-k. In this study, the crystal structure of the free form of St14f was determined at 2.5 Å resolution. Three chains were included in the asymmetric unit of the St14f free form crystal, and the structural deviation among the three chain structures was found on the C-terminal helix H and I. The St14f free form structure in solution was also investigated by nuclear magnetic resonance (NMR) residual dipolar coupling analysis, and the chain B in the crystal structure was consistent with NMR data. Compared to other crystal structures, St14f helix I exhibited a different conformation with larger B-factor values. Larger B-factor values on helix I were also found in the 14-3-3 free form structure with higher solvent contents. The mutation in St14f Helix I stabilized the complex with StFDL1. These data clearly showed that the flexibility of helix I of 14-3-3 protein plays an important role in the recognition of target protein.

Clinical Challenges in Diagnosis, Tumor Localization and Treatment of Tumor-Induced Osteomalacia: Outcome of a Retrospective Surveillance.

Tumor-induced osteomalacia (TIO) is an acquired fibroblast growth factor 23 (FGF23)-related hypophosphatemic osteomalacia caused by phosphaturic mesenchymal tumors (PMTs) developed in the bone or soft tissue. Diagnostic delay should be addressed, and ideal techniques to localize PMTs and efficient treatment options should be explored to improve the outcomes of this rare disease. To clarify the detailed clinical course and outcomes of TIO patients, retrospective questionnaire surveys were conducted among physicians from the Japanese Society for Bone and Mineral Research (JSBMR) and the Japan Endocrine Society (JES). The primary survey collected the number of TIO patients between January 2007 and December 2018. The secondary survey aimed to obtain the detailed characteristics, laboratory data, and outcomes. Eighty-eight patients (52 males, mean: 52 years old) were included, and 24 patients were clinically diagnosed with TIO without localized PMTs. The median duration from the onset to detection of high FGF23 levels was 3.4 years, with 77 patients being initially misdiagnosed. Among the methods used to detect small, localized PMTs (≤10 mm), fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography and somatostatin receptor scintigraphy were less sensitive than somatostatin receptor positron emission tomography/computed tomography (SRPET/CT). Systemic venous sampling (SVS) of FGF23 was performed in 53 patients; among them, SVS was considered useful for detecting localized PMTs in 45 patients with diverse tumor sizes. Finally, 45 patients achieved biochemical remission by surgery, 39 patients continued pharmaceutical treatment, including burosumab (11 patients), and four patients died. These results encouraged us to further increase the awareness of TIO and to improve the accessibility of SRPET/CT and SVS. Further evidence about the efficacy of new pharmaceutical treatments is awaited. © 2022 American Society for Bone and Mineral Research (ASBMR).