Modular catalytic activity of nonribosomal peptide synthetases depends on the dynamic interaction between adenylation and condensation domains

Nonribosomal peptide synthetases (NRPSs) are large multidomain enzymes for the synthesis of a variety of bioactive peptides in a modular and pipelined fashion. Here, we investigated how the condensation (C) domain and the adenylation (A) domain cooperate with each other for the efficient catalytic activity in microcystin NRPS modules. We solved two crystal structures of the microcystin NRPS modules, representing two different conformations in the NRPS catalytic cycle. Our data reveal that the dynamic interaction between the C and the A domains in these modules is mediated by the conserved "RXGR" motif, and this interaction is important for the adenylation activity. Furthermore, the "RXGR" motif-mediated dynamic interaction and its functional regulation are prevalent in different NRPSs modules possessing both the A and the C domains. This study provides new insights into the catalytic mechanism of NRPSs and their engineering strategy for synthetic peptides with different structures and properties.

Structure and assembly of the α-carboxysome in the marine cyanobacterium Prochlorococcus

Carboxysomes are bacterial microcompartments that encapsulate the enzymes RuBisCO and carbonic anhydrase in a proteinaceous shell to enhance the efficiency of photosynthetic carbon fixation. The self-assembly principles of the intact carboxysome remain elusive. Here we purified α-carboxysomes from Prochlorococcus and examined their intact structures using single-particle cryo-electron microscopy to solve the basic principles of their shell construction and internal RuBisCO organization. The 4.2 Å icosahedral-like shell structure reveals 24 CsoS1 hexamers on each facet and one CsoS4A pentamer at each vertex. RuBisCOs are organized into three concentric layers within the shell, consisting of 72, 32 and up to 4 RuBisCOs at the outer, middle and inner layers, respectively. We uniquely show how full-length and shorter forms of the scaffolding protein CsoS2 bind to the inner surface of the shell via repetitive motifs in the middle and C-terminal regions. Combined with previous reports, we propose a concomitant 'outside-in' assembly principle of α-carboxysomes: the inner surface of the self-assembled shell is reinforced by the middle and C-terminal motifs of the scaffolding protein, while the free N-terminal motifs cluster to recruit RuBisCO in concentric, three-layered spherical arrangements. These new insights into the coordinated assembly of α-carboxysomes may guide the rational design and repurposing of carboxysome structures for improving plant photosynthetic efficiency.

Allosteric regulation of nitrate transporter NRT via the signaling protein PII

Coordinated carbon and nitrogen metabolism is crucial for bacteria living in the fluctuating environments. Intracellular carbon and nitrogen homeostasis is maintained by a sophisticated network, in which the widespread signaling protein PII acts as a major regulatory hub. In cyanobacteria, PII was proposed to regulate the nitrate uptake by an ABC (ATP-binding cassette)-type nitrate transporter NrtABCD, in which the nucleotide-binding domain of NrtC is fused with a C-terminal regulatory domain (CRD). Here, we solved three cryoelectron microscopy structures of NrtBCD, bound to nitrate, ATP, and PII, respectively. Structural and biochemical analyses enable us to identify the key residues that form a hydrophobic and a hydrophilic cavity along the substrate translocation channel. The core structure of PII, but not the canonical T-loop, binds to NrtC and stabilizes the CRD, making it visible in the complex structure, narrows the substrate translocation channel in NrtB, and ultimately locks NrtBCD at an inhibited inward-facing conformation. Based on these results and previous reports, we propose a putative transport cycle driven by NrtABCD, which is allosterically inhibited by PII in response to the cellular level of 2-oxoglutarate. Our findings provide a distinct regulatory mechanism of ABC transporter via asymmetrically binding to a signaling protein.

DNA looping mediates cooperative transcription activation

Transcription factors respond to multilevel stimuli and co-occupy promoter regions of target genes to activate RNA polymerase (RNAP) in a cooperative manner. To decipher the molecular mechanism, here we report two cryo-electron microscopy structures of Anabaena transcription activation complexes (TACs): NtcA-TAC composed of RNAP holoenzyme, promoter and a global activator NtcA, and NtcA-NtcB-TAC comprising an extra context-specific regulator, NtcB. Structural analysis showed that NtcA binding makes the promoter DNA bend by ∼50°, which facilitates RNAP to contact NtcB at the distal upstream NtcB box. The sequential binding of NtcA and NtcB induces looping back of promoter DNA towards RNAP, enabling the assembly of a fully activated TAC bound with two activators. Together with biochemical assays, we propose a 'DNA looping' mechanism of cooperative transcription activation in bacteria.

Multiple masks of a Shigella podophage

In this issue of Structure, Subramanian et al. present the cryo-EM structure of Shigella podophage HRP29, which possesses a T7-like tail complex surrounded by six P22/Sf6-like tailspikes and two unique decoration proteins. These colorful masks of HRP29 record the frequent events of horizontal gene transfer during evolution.

Electroacupuncture may alleviate diabetic neuropathic pain by inhibiting the microglia P2X4R and neuroinflammation

Diabetic neuropathic pain (DNP) is a common and destructive complication of diabetes mellitus. The discovery of effective therapeutic methods for DNP is vitally imperative because of the lack of effective treatments. Although 2 Hz electroacupuncture (EA) was a successful approach for relieving DNP, the mechanism underlying the effect of EA on DNP is still poorly understood. Here, we established a rat model of DNP that was induced by streptozotocin (STZ) injection. P2X4R was upregulated in the spinal cord after STZ-injection. The upregulation of P2X4R was mainly expressed on activated microglia. Intrathecal injection of a P2X4R antagonist or microglia inhibitor attenuated STZ-induced nociceptive thermal hyperalgesia and reduced the overexpression of brain-derived neurotrophic factor (BDNF), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the spinal cord. We also assessed the effects of EA treatment on the pain hypersensitivities of DNP rats, and further investigated the possible mechanism underlying the analgesic effect of EA. EA relieved the hyperalgesia of DNP. In terms of mechanism, EA reduced the upregulation of P2X4R on activated microglia and decreased BDNF, IL-1β and TNF-α in the spinal cord. Mechanistic research of EA's analgesic impact would be beneficial in ensuring its prospective therapeutic effect on DNP as well as in extending EA's applicability.

Structural and enzymatic characterization of the sialidase SiaPG from Porphyromonas gingivalis

The sialidases, which catalyze the hydrolysis of sialic acid from extracellular glycoconjugates, are a group of major virulence factors in various pathogenic bacteria. In Porphyromonas gingivalis, which causes human periodontal disease, sialidase contributes to bacterial pathogenesis via promoting the formation of biofilms and capsules, reducing the ability for macrophage clearance, and providing nutrients for bacterial colonization. Here, the crystal structure of the P. gingivalis sialidase SiaPG is reported at 2.1 Å resolution, revealing an N-terminal carbohydrate-binding domain followed by a canonical C-terminal catalytic domain. Simulation of the product sialic acid in the active-site pocket together with functional analysis enables clear identification of the key residues that are required for substrate binding and catalysis. Moreover, structural comparison with other sialidases reveals distinct features of the active-site pocket which might confer substrate specificity. These findings provide the structural basis for the further design and optimization of effective inhibitors to target SiaPG to fight against P. gingivalis-derived oral diseases.

Analgesic effect of electroacupuncture on bone cancer pain in rat model: the role of peripheral P2X3 receptor

Upregulation of P2X3 receptor (P2X3R) has been strongly implicated in nociceptive signaling including bone cancer pain (BCP). The present study, using rat bone cancer model, aimed to explore the role of P2X3R in regulating rat pain behavior under the intervention of electroacupuncture (EA). The BCP model was successfully established by injection with MRMT-1 breast cancer cell into the medullary cavity of left tibia for 3 × 10⁴ cells/3 μL PBS in rats as revealed by obvious bone destruction, decreased paw withdrawal thresholds (PWTs), and reduced paw withdrawal latencies (PWLs). Western blot analyses showed that P2X3R expression was significantly upregulated in ipsilateral lumbar 4-6 (L4-6) dorsal root ganglia (DRG), but the difference not seen in spinal cord dorsal horn (SCDH). With the in-depth study of P2X3R activation, we observed that intrathecal injection of P2X3R agonist α,β-meATP aggravated MRMT-1 induced BCP, while injection of P2X3R inhibitor A-317491 alleviated pain. Subsequently, we demonstrated that BCP induced mechanical allodynia and thermal hyperalgesia were attenuated after EA treatment. Under EA treatment, total P2X3R protein expression in ipsilateral DRGs was decreased, and it is worth mentioning that decreased expression of P2X3R membrane protein, which indicated that both the expression and membrane trafficking of P2X3R were inhibited by EA. The immunofluorescence assay showed that EA stimulation exerted functions by reducing the expression of P2X3R-positive cells in ipsilateral DRGs of BCP rats. Ca²⁺ imaging analysis revealed that the EA stimulation decreased the percentage of α,β-meATP responsive neurons in DRGs and inhibited calcium influx. Notably, the inhibitory effect of EA on mechanical allodynia and nociceptive flinches was abolished by intrathecal injection of α,β-meATP. These findings demonstrated EA stimulation ameliorated mechanical allodynia and thermal hyperalgesia in rat model of MRMT-1-induced BCP. EA exerts analgesic effect on BCP by reducing the overexpression and functional activity of P2X3R in ipsilateral DRGs of BCP rats. Our work first demonstrates the critical and overall role of P2X3R in EA's analgesia against peripheral sensitization of MRMT-1-induced BCP and further supports EA as a potential therapeutic option for cancer pain in clinic.

Inhibition of phosphorylated calcium/calmodulin-dependent protein kinase IIα relieves streptozotocin-induced diabetic neuropathic pain through regulation of P2X3 receptor in dorsal root ganglia

Diabetic neuropathic pain (DNP) is frequent among patients with diabetes. We previously showed that P2X3 upregulation in dorsal root ganglia (DRG) plays a role in streptozotocin (STZ)-induced DNP but the underlying mechanism is unclear. Here, a rat model of DNP was established by a single injection of STZ (65 mg/kg). Fasting blood glucose was significantly elevated from the 1^st to 3^rd week. Paw withdrawal thresholds (PWTs) and paw withdrawal latencies (PWLs) in diabetic rats significantly reduced from the 2^nd to 3^rd week. Western blot analysis revealed that elevated p-CaMKIIα levels in the DRG of DNP rats were accompanied by pain-associated behaviors while CaMKIIα levels were unchanged. Immunofluorescence revealed significant increase in the proportion of p-CaMKIIα immune positive DRG neurons (stained with NeuN) in the 2^nd and 3^rd week and p-CaMKIIα was co-expressed with P2X3 in DNP rats. KN93, a CaMKII antagonist, significantly reduce mechanical hyperalgesia and thermal hyperalgesia and these effects varied dose-dependently, and suppressed p-CaMKIIα and P2X3 upregulation in the DRGs of DNP rats. These results revealed that the p-CaMKIIα upregulation in DRG is involved in DNP, which possibly mediated P2X3 upregulation, indicating CaMKIIα may be an effective pharmacological target for DNP management.

Dorsal root ganglia P2X4 and P2X7 receptors contribute to diabetes-induced hyperalgesia and the downregulation of electroacupuncture on P2X4 and P2X7

Diabetic neuropathic pain (DNP) is highly common in diabetes patients. P2X receptors play critical roles in pain sensitization. We previously showed that elevated P2X3 expression in dorsal root ganglion (DRG) contributes to DNP. However, the role of other P2X receptors in DNP is unclear. Here, we established the DNP model using a single high-dose streptozotocin (STZ) injection and investigated the expression of P2X genes in the DRG. Our data revealed elevated P2X2, P2X4, and P2X7 mRNA levels in DRG of DNP rats. The protein levels of P2X4 and P2X7 in DNP rats increased, but the P2X2 did not change significantly. To study the role of P2X4 and P2X7 in diabetes-induced hyperalgesia, we treated the DNP rats with TNP-ATP (2',3'-O-(2,4,6-trinitrophenyl)-adenosine 5'-triphosphate), a nonspecific P2X1-7 antagonist, and found that TNP-ATP alleviated thermal hyperalgesia in DNP rats. 2 Hz electroacupuncture is analgesic against DNP and could downregulate P2X4 and P2X7 expression in DRG. Our findings indicate that P2X4 and P2X7 in L4-L6 DRGs contribute to diabetes-induced hyperalgesia, and that EA reduces thermal hyperalgesia and the expression of P2X4 and P2X7.

[Validation of calculation method for dose distribution around radioactive iodine-125 particles based on AAPM TG43 report]

Objective: According to the formula provided by the TG43 report [AAPM TG43 (2004)] proposed by the American Association of Physicists in Medicine (AAPM) in 2004, we calculated the dose distribution around the radioactive iodine-125 particles, and verified the calculation accuracy of the radioactive iodine-125 particles treatment planning system. Methods: AAPM TG43 (2004) report provides two calculation methods when calculating the dose around a single radioactive source. The calculation method that does not consider the geometric structure of the radioactive source is called point source calculation method, and the calculation method that considers the geometric structure of the radioactive source is called line source calculation method. Assuming a single Amersham 6711 radioactive iodine-125 particle with an activity of 100 U, the following point doses were calculated according to the two calculation methods provided by AAPM TG43 (2004) report, at 0°, 90° directions, distances 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 and 6 cm; In the direction of 45°, the doses at 0.71, 1.41, 2.12, 2.83, 3.54, 4.24, 4.95, 5.66, 6.36, 7.07, 7.78 and 8.49 cm. On the clinically used brachytherapy planning system variseeds 8.0, the above two calculation methods are used to calculate the corresponding activity and the dose around the corresponding type of radioactive iodine-125 particles, and the function of capturing points to templates built in the planning system is used to accurately find the above corresponding point position, using a single measurement of the above corresponding point dose; and comparation of the results were performed to see if there is a statistical difference. Results: The AAPM TG43 report uses point source calculation method to calculate the dose of single Amersham 6711 radioactive iodine-125 particles with activity of 100 U at 0° and 90° directions. The points with the same distance and the same dose are 8 082.18, 1 870.08, 756.58, 381.47, 217.11, 131.91, 86.55, 58.32, 39.97, 27.42, 19.74, 14.13 Gy, respectively, at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 and 6 cm away from them. In the 45° direction, the doses at the distances of 0.71, 1.41, 2.12, 2.83, 3.54, 4.24, 4.95, 5.66, 6.36, 7.07, 7.78 and 8.49 cm are 3 957.37, 865.83, 329.99, 155.69, 84.10, 48.50, 28.49, 17.80, 11.37, 7.38, 4.98 and 3.39 Gy, respectively; For line source calculation method, radioactive particles are at the same distance as above. The doses at each point in the direction of 0° are 3 128.71, 755.44, 330.30, 180.53, 107.74, 68.56, 46.40, 32.22, 22.70, 16.00, 11.51, 8.24 Gy, respectively. The doses at each point in the direction of 90° are 8 306.46, 1 981.01, 802.74, 405.38, 230.60, 140.03, 91.83, 61.84, 42.36, 29.05, 20.91, 14.97 Gy; In the 45° direction, the dose at the corresponding distance as above is 4 020.78, 877.43, 333.49, 156.93, 84.69, 48.81, 28.65, 17.89, 11.42, 7.41, 4.99 and 3.40 Gy, respectively. The maximum dose difference (0.3%) between the two methods is 7.78 cm in the 45° direction, the maximum difference (-0.3%) between the two methods is 8.49 cm in the 45° direction, and the value of other sampling points is less than 0.3%. The closer the Amersham 6711 iodine-125 particles are to the source in the directions of 0°, 45°, and 90°, the faster the dose will drop, and the dose will drop gradually as the distance increases. Conclusion: The brachytherapy planning system variseeds 8.0 and the AAPM TG43 report calculate a maximum dose difference of 0.3%, which can accurately calculate the dose distribution around radioactive iodine-125 seeds, and provide a reliable tool for the clinical implementation of radioactive iodine-125 particles implantation for tumor treatment.

[Risk factors analysis on high-risk behaviors of drowning among students in Shufu county, Kashgar area, Xinjiang Uygur Autonomous Region]

Objective: To understand the incidence and risk factors of high-risk drowning behaviors among primary and middle school students in Shufu county, Kashgar area, Xinjiang Uygur Autonomous Region, and provide a theoretical basis for the development of drowning prevention policies and intervention measures. Methods: Cluster random sampling method was adopted in Bulakesu and Uppal of Shufu county. A total of 28 primaries and 2 middle schools were selected, and questionnaires surveyed all the students in grades 1-8. Results: A total of 14 543 questionnaires were sent out. 23.9% of primary and secondary school students had experienced high-risk drowning behavior in the past 12 months. Higher swimming level, introversion, intense curiosity, poor relationship with classmates, poor relationship with family, and open water near the school and open water near home were the risk factors of high-risk drowning behaviors. Conclusions: More attention should be paid to the psychology and high-risk behaviors of primary and middle school students, and the education of drowning knowledge and skills should be strengthened. Meanwhile, schools and communities should pay attention to the management and intervention of open water.

[Progress on the diagnosis and therapy about atopic diseases and primary immunodeficiency diseases]

Primary immunodeficiency diseases (PID) is a congenital disease caused by single gene germline mutation related to the immune system. PID patients have immune dysregulation, and are susceptible to infectious diseases, autoimmune diseases, autoimmune diseases, allergic diseases, and malignant tumors. The first symptom of some PID patients is atopic disease, therefore they go to the department of allergy, department of pediatrics and other relevant departments. How to identify and diagnose PID in allergic patients, to reduce diagnosis delay and prevent disease aggravation are the abilities that allergists, pediatricians, and doctors in other relevant departments need to master. This article summarizes the warning signs of PID in allergic patients and the mechanism of allergy combined with PID, and then summarizes the common types of PID in allergic patients, the evaluation, treatment and prevention in patients with PID and allergy.

Injectable hydrogel with dual-sensitive behavior for targeted delivery of oncostatin M to improve cardiac restoration after myocardial infarction

Myocardial infarction (MI) is a common cardiovascular disease that seriously endangers human health and complex pathophysiology (e.g., coronary artery obstruction, myocardial apoptosis, necrosis, inflammation, fibrosis, etc.) is involved. Therein, the loss of cardiomyocytes after MI in adults leads to gradual heart failure, which probably brings irreparable damage to the patient. Unfortunately, due to a cluster of limitations, currently used MI repair approaches always exhibit simple functions, low efficiency, and can hardly match the myocardial ischemia environment and clinical needs. In this study, we selected oncostatin M (OSM), a pleiotropic cytokine belonging to the interleukin-6 family that possesses an important role in cardiomyocyte dedifferentiation, cell proliferation, and regulation of inflammatory processes. Moreover, an injectable hydrogel with pH- and temperature-responsive behavior that can react with the acidic microenvironment of the ischemic myocardium was developed to deliver OSM locally. The functional hydrogel (poly (chitosan-co-citric acid-co-N-isopropyl acrylamide), P(CS-CA-NIPAM)) was fabricated by the facile reversible addition-fragmentation chain transfer polymerization and can be injected into the lesion site directly. After the gelation in situ, the OSM-loaded hydrogel exhibited continuous and localized release of OSM in response to specific pH and changes in MI rats, thereby accelerating angiogenesis and proliferation of cardiomyocytes, inhibiting myocardial fibrosis and improving cardiac function effectively. This study may provide a new perspective for the application of dual-sensitive hydrogels clinically, especially in tissue engineering for MI repair and drug delivery.

Biochemical and structural characterization of the cyanophage-encoded phosphate binding protein: implications for enhanced phosphate uptake of infected cyanobacteria

To acquire phosphorus, cyanobacteria use the typical bacterial ABC-type phosphate transporter, which is composed of a periplasmic high-affinity phosphate-binding protein PstS and a channel formed by two transmembrane proteins PstC and PstA. A putative pstS gene was identified in the genomes of cyanophages that infect the unicellular marine cyanobacteria Prochlorococcus and Synechococcus. However, it has not been determined whether the cyanophage PstS protein is functional during infection to enhance the phosphate uptake rate of host cells. Here we showed that the cyanophage P-SSM2 PstS protein was abundant in the infected Prochlorococcus NATL2A cells and the host phosphate uptake rate was enhanced after infection. This is consistent with our biochemical and structural analyses showing that the phage PstS protein is indeed a high-affinity phosphate-binding protein. We further modeled the complex structure of phage PstS with host PstCA and revealed three putative interfaces that may facilitate the formation of a chimeric ABC transporter. Our results provide insights into the molecular mechanism by which cyanophages enhance the phosphate uptake rate of cyanobacteria. Phosphate acquisition by infected bacteria can increase the phosphorus contents of released cellular debris and virus particles, which together constitute a significant proportion of the marine dissolved organic phosphorus pool. This article is protected by copyright. All rights reserved.

[Efficacy and initial clinical evaluation of optical genome mapping in the diagnosis of structural variations]

To investigate the efficacy and value of optical genome mapping (OGM) in detecting chromosomal structural variations. In a clinical study about high-precision analysis of genomic structural variation for complex genetic diseases, a retrospective study was performed on the cases with karyotyping at the department of Obstetrics and Gynecology, and Endocrinology of Peking Union Medical College Hospital from January to December 2021. Ten cases with abnormal karyotype was detected by OGM. Partial cases were verified by fluorescence in situ hybridization (FISH), SNP array or CNV-seq. Results of ten cases, nine were detected with abnormality by OGM, including unbalanced chromosomal rearrangements (n=3), translocation (n=5) and paracentric inversion (n=1), and the results were in concordance with other standard assays. However, one case with breakpoint and reconnected at centromere has not been detected. In conclusion, ten samples were comprehensively analyzed by karyotyping, FISH, SNP array or CNV-seq, and OGM, and results demonstrated that optical genome mapping as a new technology can not only detect unbalanced rearrangements such as copy number variants as well as balanced translocations and inversions, but more importantly, it can refine breakpoints and orientation of duplicated segments or insertions. So it can contribute to the diagnosis of genetic diseases and prevent birth defect. However, the current technology is not yet capable of detecting breakpoints of balanced structural variations lying within unmapped regions.

[Effect of electroacupuncture and pretreatment of electroacupuncture on pain sensitization and expression of P2X7R in spinal dorsal horn in rats with diabetic neuropathic pain]

OBJECTIVE

To observe the occurrence time of neuralgia and the expression of purinergic ligand-gated ion channel 7 receptor (P2X7R) in the dorsal horn of the spinal cord after intraperitoneal injection of streptozotocin (STZ) in diabetic rats, and to explore the effect of electroacupuncture (EA) and pretreatment of EA on the heat pain threshold and expression of P2X7R in the spinal dorsal horn in rats with diabetic neuropathic pain (DNP), and to explore the possible mechanism of EA for DNP.

METHODS

PartⅠ: Thirty male SD rats were randomly selected from 64 male SD rats as the control group; the remaining rats were given intraperitoneal injection of STZ (10 mg/mL) at a dose of 65 mg/kg to establish the diabetes model, and 30 rats were successfully modeled as the model group. The control group and the model group were divided into three subgroups respectively at 7, 14 and 21 days, with 10 rats in each subgroup. Body mass, fasting blood glucose (FBG) and thermal pain threshold were recorded at 7, 14 and 21 days after injection; the expression of P2X7R in spinal dorsal horn was detected by Western blot. PartⅡ: Eight SD rats were randomly selected from 35 male SD rats as the blank group, and the remaining 27 rats were given intraperitoneal injection of STZ (10 mg/mL) at a dose of 65 mg/kg to establish the diabetes model. The 24 rats with successful diabetes model were randomly divided into a DNP group, an EA group and a pre-EA group, 8 rats in each group. Fifteen to 21 days after STZ injection, the EA group received EA at "Zusanli" (ST 36) and "Kunlun" (BL 60), continuous wave, frequency of 2 Hz, 30 min each time, once a day; the intervention method in the pre-EA group was the same as that in the EA group. The intervention time was 8 to 14 days after STZ injection. The body mass, FBG and thermal pain threshold were recorded before STZ injection and 7, 14 and 21 days after STZ injection; the expression of P2X7R in spinal dorsal horn was detected by Western blot 21 days after injection.

RESULTS

PartⅠ: Compared with the control group, in the model group, the body mass was decreased and FBG was increased 7, 14 and 21 days after STZ injection (P<0.01), and the thermal pain threshold was decreased 14 and 21 days after STZ injection (P<0.05), and the expression of P2X7R in spinal dorsal horn was increased 7, 14 and 21 days after STZ injection (P<0.05, P<0.01). PartⅡ: Compared with the blank group, in the DNP group, the body mass was decreased and fasting blood glucose were increased 7, 14 and 21 days after STZ injection (P<0.01). Compared with the DNP group, in the pre-EA group, the heat pain threshold was increased 14 and 21 days after STZ injection (P<0.05), while in the EA group, the heat pain threshold was increased 21 days after STZ injection (P<0.01), and the expression of P2X7R in the dorsal horn in the EA group and the pre-EA group was decreased (P<0.01).

CONCLUSION

The diabetic neuropathic pain is observed 14 days after STZ injection. EA could not only treat but also prevent the occurrence of DNP, and its mechanism may be related to down-regulation of P2X7R expression in the dorsal horn of the spinal cord.

Capsid Structure of Anabaena Cyanophage A-1(L)

A-1(L) is a freshwater cyanophage with a contractile tail that specifically infects Anabaena sp. PCC 7120, one of the model strains for molecular studies of cyanobacteria. Although isolated for half a century, its structure remains unknown, which limits our understanding on the interplay between A-1(L) and its host. Here we report the 3.35 Å cryo-EM structure of A-1(L) capsid, representing the first near-atomic resolution structure of a phage capsid with a T number of 9. The major capsid gp4 proteins assemble into 91 capsomers, including 80 hexons: 20 at the center of the facet and 60 at the facet edge, in addition to 11 identical pentons. These capsomers further assemble into the icosahedral capsid, via gradually increasing curvatures. Different from the previously reported capsids of known-structure, A-1(L) adopts a noncovalent chainmail structure of capsid stabilized by two kinds of mortise-and-tenon inter-capsomer interactions: a three-layered interface at the pseudo 3-fold axis combined with the complementarity in shape and electrostatic potential around the 2-fold axis. This unique capsomer construction enables A-1(L) to possess a rigid capsid, which is solely composed of the major capsid proteins with an HK97 fold. IMPORTANCE Cyanobacteria are the most abundant photosynthetic bacteria, contributing significantly to the biomass production, O2 generation, and CO2 consumption on our planet. Their community structure and homeostasis in natural aquatic ecosystems are largely regulated by the corresponding cyanophages. In this study, we solved the structure of cyanophage A-1(L) capsid at near-atomic resolution and revealed a unique capsid construction. This capsid structure provides the molecular details for better understanding the assembly of A-1(L), and a structural platform for future investigation and application of A-1(L) in combination with its host Anabaena sp. PCC 7120. As the first isolated freshwater cyanophage that infects the genetically tractable model cyanobacterium, A-1(L) should become an ideal template for the genetic engineering and synthetic biology studies.

Structure and assembly pattern of a freshwater short-tailed cyanophage Pam1

Despite previous structural analyses of bacteriophages, quite little is known about the structures and assembly patterns of cyanophages. Using cryo-EM combined with crystallography, we solve the near-atomic-resolution structure of a freshwater short-tailed cyanophage, Pam1, which comprises a 400-Å-long tail and an icosahedral capsid of 650 Å in diameter. The outer capsid surface is reinforced by trimeric cement proteins with a β-sandwich fold, which structurally resemble the distal motif of Pam1's tailspike, suggesting its potential role in host recognition. At the portal vertex, the dodecameric portal and connected adaptor, followed by a hexameric needle head, form a DNA ejection channel, which is sealed by a trimeric needle. Moreover, we identify a right-handed rifling pattern that might help DNA to revolve along the wall of the ejection channel. Our study reveals the precise assembly pattern of a cyanophage and lays the foundation to support its practical biotechnological and environmental applications.

[Humanized BCMA CAR-T cell salvage therapy in two refractory multiple myeloma patients who progressed after their murine BCMA CAR-T cell therapy]

Objective: To observe the efficacy and safety of humanized anti-BCMA chimeric antigen receptor modified (BCMA CAR) -T cell therapy after disease progression with their murine BCMA CAR-T cell therapy in patients with relapsed/refractory multiple myeloma (MM) . Methods: Study participants underwent leukapheresis to collect T cells for BCMA CAR-T manufacturing. Patients were pretreated with intensive chemotherapy (fludarabine combined with cytarabine) before CAR-T therapy. Adverse events (AEs) , CAR DNA expansion, and cytokine were monitored. In vitro, transfection efficacy, specific cytotoxicity, and inflammatory response were detected when co-cultured with effector and target cells. Results: Patient (PT) 1 and 2 achieved complete remission (CR) and disease stability at 3 months post murine CAR-T therapy. However, 16 and 18 months later, they experienced progression of disease (PD) , and patient 1 presented with extramedullary disease at PD. Both of the patients received humanized CAR-T therapy and achieved partial remission (PR) and very good partial remission (VGPR) post humanized CAR-T therapy. PT1 achieved CR of the soft tissue masses at 4 months post humanized CAR-T therapy. Notably, the median peak of the BCMA CAR-T cells, copy of BCMA CAR gene, persistence of BCMA CAR-T, and the peak levels of IL-6, IL-8, IL-10, IFN-γ and TNF-α were higher in humanized CAR-T therapy than those in the murine CAR-T therapy. During the murine CAR-T therapy, both of the patients experienced grade 1 CRS and no ICANS. PT1 experienced grade 3 CRS and grade 2 ICANS during humanized CAR-T therapy, which were relieved by supportive care. Grade 2 CRS was observed for patient 2 during humanized CAR-T therapy. Humanized BCMA CAR-T cells showed a higher inflammatory response and in vitro cytotoxicity than that of murine BCMA CAR-T cells with effector/targets cells at 1∶1 over 48 hours (P<0.001) . The proportions of residual cells in humanized BCMA CAR-T and murine CAR-T were (17.38±5.18) % vs (28.27±4.58) %, (13.25±1.62) % vs (22.77±1.77) % for PT1 and PT2, respectively. Conclusions: The humanized BCMA CAR-T cell therapy was efficient and safe for patients who experienced progression of disease after the murine CAR-T therapy, especially for patients with extramedullary disease.

[Analysis of local reactions and efficacy of CD19 chimeric antigen receptor-modified T cells therapy in recurrent/refractory B-cell lymphoma with >7.5 cm lesions]

目的

观察病灶>7.5 cm的复发/难治B细胞非霍奇金淋巴瘤（R/R NHL）患者CD19嵌合抗原受体T细胞（CAR-T细胞）治疗的肿瘤局部反应及疗效。

方法

以2018年8月至2020年5月接受CD19 CAR-T细胞治疗的病灶>7.5 cm的32例R/R NHL患者为研究对象，流式细胞仪检测CD19CAR-T细胞的体内扩增情况；酶联免疫吸附测定法检测患者外周血中细胞因子水平；观察全身不良反应及肿瘤局部反应，分析总有效率（ORR）及总生存（OS）情况。

结果

① 32例患者CAR-T细胞治疗后，13例获得完全缓解（CR）（40.63％），10例获得部分缓解（PR）（31.25％），ORR为71.88％。② 23例有效患者均发生细胞因子释放综合征（CRS），其中1～2级13例，3～4级10例；而疾病稳定+疾病进展（SD+PD）组9例患者CRS均为1～2级（P＝0.030）。③共15例（46.9％）患者发生肿瘤局部反应，其中CR 9例、PR 5例、SD 1例，肿瘤局部反应包括：浅表肿物直径增大且伴红肿热痛；深部肿物表现为腹痛、腹胀、憋气以及肿瘤局部疼痛、烧灼，瘤体增大或伴局部水肿；肿瘤局部出现渗出性病变，可见于腹腔、胸膜腔等。④有效组CD19 CAR-T细胞峰值高于SD+PD组［16.8％（5.3％～48.2％）对2.9％（1.5％～5.7％），z＝−4.297，P<0.001］，有效组中出现肿瘤局部反应患者CD19 CAR-T细胞峰值高于未出现肿瘤局部反应患者［22.2％（10.5％～48.2％）对12.6％（5.3％～21.6％），z＝−3.213，P＝0.001］，多发肿块组CD19 CAR-T细胞峰值高于单发肿块组［35.8％（1.5％～48.2％）对16.8％（10.5％～18.5％），z＝−2.023，P＝0.040］。⑤肿瘤局部反应出现和瘤体缩小时间，均较全身不良反应时间延迟。⑥有效患者中出现肿瘤局部反应者OS率高于未出现肿瘤局部反应者，但差异无统计学意义（75.0％对34.6％，P＝0.169）。

结论

病灶>7.5 cm的R/R NHL患者CD19 CAR-T细胞治疗，近一半出现肿瘤局部反应，发生时间迟于全身不良反应开始的时间。临床试验注册：中国临床试验注册中心（ChiCTR1800018059）

Complex structure reveals CcmM and CcmN form a heterotrimeric adaptor in β-carboxysome

Carboxysome is an icosahedral self-assembled microcompartment that sequesters RuBisCO and carbonic anhydrases within a selectively permeable protein shell. The scaffolding proteins, CcmM, and CcmN were proposed to act as adaptors that crosslink the enzymatic core to shell facets. However, the details of interaction pattern remain unknown. Here we obtained a stable heterotrimeric complex of CcmM γ-carbonic anhydrase domain (termed CcmM^NT ) and CcmN, with a 1:2 stoichiometry, which interacts with the shell proteins CcmO and CcmL in vitro. The 2.9 Å crystal structure of this heterotrimer revealed an asymmetric bundle composed of one CcmM^NT and two CcmN subunits, all of which adopt a triangular left-handed β-helical barrel structure. The central CcmN subunit packs against CcmM^NT and another CcmN subunit via a wall-to-edge or wall-to-wall pattern, respectively. Together with previous findings, we propose CcmM^NT -CcmN functions as an adaptor to facilitate the recruitment of shell proteins and the assembly of intact β-carboxysome.

[Clinical efficacy and safety of moxibustion as adjuvant therapy for COPD in stable phase: a Meta-analysis]

OBJECTIVE

To systematically evaluate the efficacy and safety of conventional therapy combined with moxibustion in the treatment of chronic obstructive pulmonary disease (COPD) in stable phase based on Meta-analysis medicine.

METHODS

The randomized controlled trials (RCTs) of moxibustion as adjuvant therapy for COPD were retrieved from the databases of CNKI, Wanfang, SinoMed, PubMed, Web of Science, Cochrane Library and Ebsco. RevMan5.3 software was used for Meta analysis, and the quality of evidence was evaluated according to GRADE standards.

RESULTS

A total of 16 RCTs were included, involving 1425 patients. The results of Meta-analysis showed that: compared with the conventional treatment, ①the adjuvant therapy with moxibustion had advantages in reducing the number of acute exacerbations [MD=-0.31, 95%CI:-0.49--0.13, P=0.0006]; ②the adjuvant therapy with moxibustion improved lung function significantly [FEV1% (MD=4.00, 95%CI:2.63-5.37, P<0.000 01) and FEV1/FVC (MD=3.56, 95%CI:1.69-5.43, P=0.000 2)]; ③the adjuvant therapy with moxibustion could extend the 6 min walking distance (6WMD) (MD=35.00, 95%CI:18.02-51.99, P<0.000 1); ④the adjuvant therapy with moxibustion could improve the modified British Medical Research Council breathing questionnaire (mMRC) classification significantly (MD=-0.62, 95%CI:-1.18--0.05, P=0.03); ⑤no adverse reaction was reported in the included literature.

CONCLUSION

The efficacy of moxibustion as adjuvant therapy for COPD in stable phase is better than that of simple conventional therapy. Due to insufficient clinical evidence and the limitations of this study, clinical safety is unclear and further evidence is needed to support the results.

[Pilot study of genetic counseling and prenatal diagnosis in androgen insensitivity syndrome: with 3 families reports]

Objective: To explore genetic counseling and prenatal diagnosis strategies for women who have androgen insensitivity syndrome (AIS) family history or pregnancy history of AIS proband. Methods: Three families of complete AIS (CAIS) were retrospectively reported and summarized. The subsequent pregnancies and processes of prenatal diagnosis were followed up. Results: Among three CAIS families, one family had androgen receptors (AR) gene mutation diagnosis; the other two families were diagnosed clinically without gene diagnosis. All three mothers of CAIS probands were in pregnant again when they sought counseling, with gestational weeks between 7－13 weeks. They underwent chorionic villi sampling or amniocentesis in their second trimester (at 12, 16, 17 weeks respectively). Chromosome gender of all three fetuses were 46,XY, which was inconsistent with the ultrasonographic phenotype of external genitalia. All patients chose selective abortion in their second trimester. The external genitalia of all aborted fetuses were female phenotype, which supported the diagnosis of CAIS. Conclusion: Genetic counseling and prenatal diagnosis should be provided to high-risk patients with family history of AIS or proband pregnancy history, so as to achieve the goal of good childbearing and sound childrearing.

[Discussion on "guiding meridian sinew qi along with meridian running course" in treatment of meridian sinew disorders]

It is to determine the effect mechanism and therapeutic method of the idea as "guiding meridian sinew qi along with meridian running course" for meridian sinew disorders so as to provide the reference for clinical treatment of these disorders. "Guiding meridian sinew qi along with meridian running course" is the summary for the approach to meridian sinew disorders by YANG Shang-shan, recorded in Huangdi Mingtang Jing (The Yellow Emperor's Acupoints Canon of Mingtang ), but the concrete statement on it had been lost. By investigating the existing ancient works, the authors discussed the specific meaning of jinqi (meridian sinew qi ), the relationship between jingjin (meridian sinew) and jingmai (meridian), the method of "guiding meridian sinew qi along with meridian running course" and its preferable acupoint selection for treatment of meridian sinew disorders with both the primary and the secondary considered.

[CD44 regulates biological behavior and Ras signaling pathway in nasopharyngeal carcinoma stem cells]

Objective: To study the biological behavior of nasopharyngeal carcinoma stem cells and to explore the activation of Ras signaling pathway regulated by CD44. Methods: CNE2-SC and 5-8F-SC were nasopharyngeal carcinoma stem cells and obtained by serum-free suspension culture. Cell counting kit-8 (CCK-8) assay, colony formation assay, Transwell migration assay, cell adhesion array were used to investigate the growth, proliferation, migration and adhesion of nasopharyngeal carcinoma stem cells. Western blot test was used to detect the expressions of Ras signaling pathway related proteins and siRNA-mediated interference was used to determine the activation of Ras signaling pathway regulated by CD44. Results: The growth rates of CNE2-SC and 5-8F-SC cells were significantly lower than those of nasopharyngeal carcinoma cells at 24, 48 and 72 hours after inoculation (P<0.05). After 14 days of implantation, the colony formation rates of CNE2-SC (44.5±1.9)% and 5-8F-SC (47.4±1.8)% were higher than those of CNE2 (34.9±1.5)% and 5-8F (37.2±1.7)%, respectively(P<0.01). The migration cell number of CNE2-SC was (87.6±7.8), 3.97 times higher than that of CNE2 (P<0.01). The migration cell number of 5-8F-SC was (67.2±5.7), 3.07 times higher than 5-8F (P<0.01). The adhesion rates of CNE2-SC and CNE2 cells were (42.1±7.6)% and (8.9±2.0)%, respectively at 3 hours after inoculation and were (82.4±5.0)% and (12.1±2.2)% at 6 hours after inoculation, respectively. The adhesion rate of CNE2-SC cells was higher than that of CNE2 cells (all P<0.01). The adhesion rates of 5-8F-SC and 5-8F cells were (53.6±6.1)% and (7.3±1.5)% at 3 hours after inoculation, and (90.7±3.6)% and (11.0±1.2)% at 6 hours after inoculation, respectively. The adhesion rate of 5-8F-SC cells was higher than that of 5-8F cells (P<0.01). The expression levels of CD44, Ras and N-cadherin were significantly higher, while phosphatase and tensin homolog deleted on chromosome 10 (PTEN), E-cadherin in nasopharyngeal carcinoma stem cells were lower than those of the nasopharyngeal carcinoma cells. Furthermore, the levels of phosphorylated mitogen extracellular kinase1/2 (p-MEK1/2) and phosphorylated extracellular signal-regulated protein kinase1/2 (p-ERK1/2)were significantly increased in nasopharyngeal carcinoma stem cells (P<0.01). Correlation analysis showed that the protein expression levels of CD44 was highly positively correlated with RAS in nasopharyngeal carcinoma stem cells(r=0.985, P=0.002; r=0.962, P=0.038). Deletion of CD44 in CNE2-SC decreased the expression levels of HER-2, Ras and p-ERK1/2, p-Akt and phosphorylated protein kinase C-δ(p-PKCδ) (P<0.01). Conclusions: Despite compare to the nasopharyngeal carcinoma cell, nasopharyngeal carcinoma stem cells grows at a relatively slow rate, the capacities of clone formation, migration, adhesion are promoted. This may be related to the CD44-regulated abnormal activation of Ras signaling pathway.

[Epidemiological and virus molecular characterization of dengue fever outbreak in Hunan province, 2018]

Objective: To analyze the epidemiological and etiological characteristics of a dengue fever outbreak in Hunan province in 2018. Methods: Real-time PCR assay was performed for the laboratory diagnosis of 8 suspected dengue fever cases. Etiological surveillance was performed in 186 suspected dengue fever cases and fever cases who had close contacts with dengue fever patients. C6/36 cells was used for the virus isolation from acute phase serum. By sequencing the full length of E genes of 15 dengue virus strains, phylogenetic analysis was performed based on the sequences obtained, including reference sequences from the NCBI GenBank database, the serotypes and gene subtypes of the virus were analyzed to trace the possible source of transmission. An emergency monitoring of vector density and a retrospective survey of sero-epidemiology in healthy population were conducted in the epidemic area. Results: In the serum samples of 8 suspected patients, 6 were dengue virus RNA positive, and 4 were NS1 antigen positive. In 186 suspected patients, 96 were dengue virus nucleic acid, NS1 antigen or antibody positive in etiological test. A total of 64 dengue virus strains were isolated. The phylogenetic analysis showed that all the dengue virus strains belonged to type 2, which might be from Guangdong or Zhejiang provinces. The Bretub index was up to 65, indicating an extremely high risk of transmission. The positive rate of the dengue virus IgG antibody was 0.53%(2/377) in retrospective survey of 377 healthy people. Conclusion: The field epidemiologic and the molecular genetics analyses showed the outbreak of dengue fever in Hunan in 2018 was caused by imported cases and dengue virus 2.

[Maintenance therapy following CD19 CAR-T treatment for relapsed B-cell acute lymphoblastic leukemia after allogeneic hematopoietic stem cell transplantation]

Objective: This study aimed to evaluate the maintenance therapy following an anti-CD19-CAR T-cell therapy for a B-cell acute lymphoblastic leukemia (ALL) patient who relapsed after allogeneic hematopoietic cell transplantation (allo-HSCT) and investigate the effect of donor stem cells and donor T lymphocyte infusion on the amplification of CD19 CAR-T cells. Methods: One refractory B-ALL patient relapsed after murine CD19 CAR-T cell therapy followed by a sibling allo-HSCT. He underwent a humanized CD19 CAR-T cell therapy followed by donor stem cell and donor T lymphocytes infusions as maintenance therapy in our hospital. The level of cytokines, the proportion of CD19 CAR-T cell, the level of CAR19 DNA expression in the peripheral blood, and the proportion of leukemia cells and donor chimerism in the bone marrow were detected. Correspondingly, T lymphocytes from the C57 spleen were separated to modify the CD19 CAR lentivirus and refused into C57 mice, and after 14 days, the B lymphocytes from C57 mice were separated and refused into the same C57 mice. The CD19 CAR T cells, B cells, and CD19 CAR gene counts in the peripheral blood were evaluated at different time points. Results: ①The patient achieved a complete response (CR) 14 days after a humanized CD19 CAR-T therapy with grade 1 cytokine release syndrome (CRS) and restored a donor chimerism to 99.76%. ② Following the remission from humanized CD19 CAR-T therapy, the patient received a maintenance therapy of donor stem cell infusion. Mild graft-versus-host disease (GVHD) manifested 24 days after infusion with an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression in the peripheral blood. It fell with the remission of GVHD. The patient maintained CR and 99.69% donor chimerism during this period. ③ Throughout the subsequent donor T lymphocytes maintenance therapy, mild GVHD surfaced12 days after infusion without an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression in the peripheral blood. The patient maintained CR and 99.87% donor chimerism during this period. ④ In vivo experiments on C57 mice confirmed that the proportion of CD19 CAR-T cells and the level of CAR19 DNA expression were upregulated in mice following CAR-T cell infusion, accompanied by depletion of CD19(+) B lymphocyte. After infusion of CD19(+) B lymphocyte cells, an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression in the peripheral blood were observed again. Conclusions: The infusion of donor stem cells and donor T lymphocytes could be used as a maintenance treatment after CD19 CAR-T cell therapy for B-ALL patients who relapsed after allo-HSCT. Infusion of donor stem cells induced an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression with the occurrence of GVHD. It might lead to further elimination of minimal residual disease.

Molecular basis for the assembly of RuBisCO assisted by the chaperone Raf1

The folding and assembly of RuBisCO, the most abundant enzyme in nature, needs a series of chaperones, including the RuBisCO accumulation factor Raf1, which is highly conserved in cyanobacteria and plants. Here, we report the crystal structures of Raf1 from cyanobacteria Anabaena sp. PCC 7120 and its complex with RuBisCO large subunit RbcL. Structural analyses and biochemical assays reveal that each Raf1 dimer captures an RbcL dimer, with the C-terminal tail inserting into the catalytic pocket, and further mediates the assembly of RbcL dimers to form the octameric core of RuBisCO. Furthermore, the cryo-electron microscopy structures of the RbcL-Raf1-RbcS assembly intermediates enable us to see a dynamic assembly process from RbcL₈Raf1₈ to the holoenzyme RbcL₈RbcS₈. In vitro assays also indicate that Raf1 can attenuate and reverse CcmM-mediated cyanobacterial RuBisCO condensation. Combined with previous findings, we propose a putative model for the assembly of cyanobacterial RuBisCO coordinated by the chaperone Raf1.

The model cyanobacteria Anabaena sp. PCC 7120 possess an intact but partially degenerated gene cluster encoding gas vesicles

Background

Bacterial gas vesicles, composed of two major gas vesicle proteins and filled with gas, are a unique class of intracellular bubble-like nanostructures. They provide buoyancy for cells, and thus play an essential role in the growth and survival of aquatic and soil microbes. Moreover, the gas vesicle could be applied to multimodal and noninvasive biological imaging as a potential nanoscale contrast agent. To date, cylinder-shaped gas vesicles have been found in several strains of cyanobacteria. However, whether the functional gas vesicles could be produced in the model filamentous cyanobacteria Anabaena sp. PCC 7120 remains controversial.

Results

In this study, we found that an intact gvp gene cluster indeed exists in the model filamentous cyanobacteria Anabaena sp. PCC 7120. Real-time PCR assays showed that the gvpA gene is constitutively transcribed in vivo, and its expression level is upregulated at low light intensity and/or high growth temperature. Functional expression of this intact gvp gene cluster enables the recombinant Escherichia coli to gain the capability of floatation in the liquid medium, thanks to the assembly of irregular gas vesicles. Furthermore, crystal structure of GvpF in combination with enzymatic activity assays of GvpN suggested that these two auxiliary proteins of gas vesicle are structurally and enzymatically conserved, respectively.

Conclusions

Our findings show that the laboratory strain of model filamentous cyanobacteria Anabaena sp. PCC 7120 possesses an intact but partially degenerated gas vesicle gene cluster, indicating that the natural isolate might be able to produce gas vesicles under some given environmental stimuli for better floatation.

Crystal structure of a novel fold protein Gp72 from the freshwater cyanophage Mic1

Cyanophages, widespread in aquatic systems, are a class of viruses that specifically infect cyanobacteria. Though they play important roles in modulating the homeostasis of cyanobacterial populations, little is known about the freshwater cyanophages, especially those hypothetical proteins of unknown function. Mic1 is a freshwater siphocyanophage isolated from the Lake Chaohu. It encodes three hypothetical proteins Gp65, Gp66, and Gp72, which share an identity of 61.6% to 83%. However, we find these three homologous proteins differ from each other in oligomeric state. Moreover, we solve the crystal structure of Gp72 at 2.3 Å, which represents a novel fold in the α + β class. Structural analyses combined with redox assays enable us to propose a model of disulfide bond mediated oligomerization for Gp72. Altogether, these findings provide structural and biochemical basis for further investigations on the freshwater cyanophage Mic1.

Structural and functional insights into the Asp1/2/3 complex mediated secretion of pneumococcal serine-rich repeat protein PsrP

The accessory sec system consisting of seven conserved components is commonly distributed among pathogenic Gram-positive bacteria for the secretion of serine-rich-repeat proteins (SRRPs). Asp1/2/3 protein complex in the system is responsible for both the O-acetylation of GlcNAc and delivering SRRPs to SecA2. However, the molecular mechanism of how Asp1/2/3 transport SRRPs remains unknown. Here, we report the complex structure of Asp1/2/3 from Streptococcus pneumoniae at 2.9 Å. Further functional assays indicated that Asp1/2/3 can stimulate the ATPase activity of SecA2. In addition, the deletion of asp1/2/3 gene resulted in the accumulation of a secreted version of PsrP with an altered glycoform in protoplast fraction of the mutant cell, which suggested the modification/transport coupling of the substrate. Altogether, these findings not only provide structural basis for further investigations on the transport process of SRRPs, but also uncover the indispensable role of Asp1/2/3 in the accessory sec system.

Genomic Analysis of Mic1 Reveals a Novel Freshwater Long-Tailed Cyanophage

Lake Chaohu, one of the five largest freshwater lakes in China, has been suffering from severe cyanobacterial blooms in the summer for many years. Cyanophages, the viruses that specifically infect cyanobacteria, play a key role in modulating cyanobacterial population, and thus regulate the emergence and decline of cyanobacterial blooms. Here we report a long-tailed cyanophage isolated from Lake Chaohu, termed Mic1, which specifically infects the cyanobacterium Microcystis aeruginosa. Mic1 has an icosahedral head of 88 nm in diameter and a long flexible tail of 400 nm. It possesses a circular genome of 92,627 bp, which contains 98 putative open reading frames. Genome sequence analysis enabled us to define a novel terminase large subunit that consists of two types of intein, indicating that the genome packaging of Mic1 is under fine control via posttranslational maturation of the terminase. Moreover, phylogenetic analysis suggested Mic1 and mitochondria share a common evolutionary origin of DNA polymerase γ gene. All together, these findings provided a start-point for investigating the co-evolution of cyanophages and its cyanobacterial hosts.

Cryo-electron Microscopy Structure and Transport Mechanism of a Wall Teichoic Acid ABC Transporter

The wall teichoic acid (WTA) is a major cell wall component of Gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), a common cause of fatal clinical infections in humans. Thus, the indispensable ABC transporter TarGH, which flips WTA from cytoplasm to extracellular space, becomes a promising target of anti-MRSA drugs. Here, we report the 3.9-Å cryo-electron microscopy (cryo-EM) structure of a 50% sequence-identical homolog of TarGH from Alicyclobacillus herbarius at an ATP-free and inward-facing conformation. Structural analysis combined with activity assays enables us to clearly decode the binding site and inhibitory mechanism of the anti-MRSA inhibitor Targocil, which targets TarGH. Moreover, we propose a "crankshaft conrod" mechanism utilized by TarGH, which can be applied to similar ABC transporters that translocate a rather big substrate through relatively subtle conformational changes. These findings provide a structural basis for the rational design and optimization of antibiotics against MRSA.IMPORTANCE The wall teichoic acid (WTA) is a major component of cell wall and a pathogenic factor in methicillin-resistant Staphylococcus aureus (MRSA). The ABC transporter TarGH is indispensable for flipping WTA precursor from cytoplasm to the extracellular space, thus making it a promising drug target for anti-MRSA agents. The 3.9-Å cryo-EM structure of a TarGH homolog helps us to decode the binding site and inhibitory mechanism of a recently reported inhibitor, Targocil, and provides a structural platform for rational design and optimization of potential antibiotics. Moreover, we propose a "crankshaft conrod" mechanism to explain how a big substrate is translocated through subtle conformational changes of type II exporters. These findings advance our understanding of anti-MRSA drug design and ABC transporters.

[Impact of maternal X chromosome aneuploidies on cell free DNA prenatal screening]

Objective: To investigate the impact of maternal X chromosome aneuploidies on cell free DNA (cf-DNA) prenatal screening. Methods: After genetic counseling, invasive prenatal diagnosis was provided for the 124 cases with high risk of sex chromosome aneuploidie (SCA) indicated by cf-DNA prenatal screening. For cases with discordant results of fetal prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte was collected for copy number variation sequencing (CNV-seq) to detect whether the maternal X chromosome was carrying variations. Results: Totally, 124 cases with high risks of SCA indicated by cf-DNA prenatal screening, 9 cases refused to take invasive prenatal diagnosis, while the remaining 115 cases received. Among the 115 cases, 41 cases received accordant results with cf-DNA prenatal screening while 74 cases discordant. Among the 74 cases with discordant results, 19 cases were indicated with maternal X chromosome variations by maternal leukocyte CNV-seq, which accounting for 25.7% (19/74) of the SCA false positive cases, and 15.3% (19/124) of all SCA cases. Conclusions: Pregnant women with X chromosome variations may affect the results of cf-DNA prenatal screening, resulting in false positive or false negative outcomes, it should be emphasized that the cf-DNA results may be affected by maternal X chromosome variations. In cases with discordant results of prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte CNV-seq is recommended to find the reasons of false positive or negative results. And cf-DNA prenatal screening is not recommended for pregnant women who are already known with X chromosome variations.

Ginsenoside Rb1 attenuates cardiomyocyte apoptosis induced by myocardial ischemia reperfusion injury through mTOR signal pathway

OBJECTIVE

Ginsenoside Rb1 (GRb1) is known to play an effective protection on myocardial infarction, yet its therapeutic mechanism on myocardial ischemia/reperfusion (I/R) injury has remained obscure. Here we sought to investigate the protective mechanism of GRb1 preconditioning on myocardial I/R injury in rats.

METHODS AND RESULTS

We report here that GRb1 preconditioning could improve myocardial I/R injury induced-cardiac functions including LVDP, -dp/dt min and + dp/dt max; however, the heart rate (HR) was maintained at a level comparable to the I/R group. Additionally, in I/R injury group given GRb1 preconditioning, release of myocardial enzymes (CK-MB and Trop l) and CtsB was decreased. Moreover, GRb1 decreased the expression of apoptotic related proteins e.g. cleaved-caspase 3; however, the ratio of Bcl-2/Bax related to anti-apoptosis was decreased. The study was extended by injecting rapamycin intraperitoneally before GRb1 pretreatment. Thus, mTOR pathway was significantly upregulated after GRb1 pretreatment when compared with I/R. Remarkably, the anti-apoptosis protection of GRb1 pretreatment was attenuated by rapamycin. Furthermore, GRb1 effectively reduced the infarct size thus supporting its role in anti-myocardial I/R injury.

CONCLUSIONS

It is concluded that GRb1 preconditioning can ameliorate myocardial I/R injury as manifested by the improvement of cardiac function indices; moreover, release of myocardial enzymes, namely, CK-MB, Trop l and CtsB was reduced. More importantly, we have shown that the protective effect of GRb1 against I/R injury induced cardiomyocyte apoptosis is associated with the activation of mTOR signal pathway as evident by the use of rapamycin.

[The value of rapid on-site evaluation (ROSE) of bronchoscopy in the diagnosis of pulmonary complications after allogeneic hematopoietic stem cell transplantation]

Objective: To investigate the value of rapid on-site evaluation (ROSE) of bronchoscopy in the diagnosis of pulmonary complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: A retrospective analysis was conducted on the diagnosis and treatment process before and after ROSE examination of 12 patients with pulmonary complications after allo-HSCT who were admitted to the Department of hematology, Tianjin First Central Hospital from January 2017 to June 2019. The diagnostic accuracy of the ROSE was evaluated by comparing the initial diagnosis of ROSE with the final clinical diagnosis. At the same time, the safety of ROSE examination was evaluated and two typical cases were shared. Results: In the 12 transbronchial lung biopsies, there were 5 cases of organizing pneumonia, 3 cases of bronchiolitis obliterans with organizing pneumonia, 1 case of pulmonary fibrosis, 1 case of acute fibrinous and organizing pneumonia, 1 case of pseudomembranous tracheobronchial aspergillosis and 1 case of uncertain diagnosis evaluated by ROSE. Compared with the final clinical diagnosis, there were 10 cases of accurate diagnosis made by ROSE (10/12). All patients were well tolerant to the operation of bronchoscopy. There was only a small amount of bleeding observed during the operation, without pneumothorax and hemoptysis. And no complications related to ROSE occurred. According to the initial diagnosis of ROSE, 10 cases of non-infectious pulmonary complications were treated with methylprednisolone or other immunosuppressive agents and 1 case of Aspergillus infection was given antifungal therapy. Seven patients with non-infectious pulmonary complications improved after treatment. One patient obtained uncertain diagnosis by ROSE was later diagnosed with virus infection by next generation sequencing technology and improved after treatment with foscarnet sodium and immunoglobulin. As of June 30, 2019, 7 patients improved and 5 died. Conclusion: ROSE has the advantages of diagnostic accuracy and rapidity, and is very suitable for patients with critical illness after hematopoietic stem cell transplantation, who are in urgent need of definite diagnosis and prompt treatment, which is beneficial to improve the prognosis of patients.

[3D printing non-coplanar template-assisted 125-iodine seed implantation for thorax movement tumor: individual template design method]

Objective: To compare the dosimetric data between preoperative plans and postoperative verification in computed tomography CT-guided and 3D printing template-assisted 125-iodine ((125)I) seed implantation for thorax movement tumor and to explore the feasibility and accuracy of the individualized template design method. Methods: A total of 35 patients, 20 males and 15 females with median age of 62 (17-87) years old, who registered from January 2016 to December 2017 applied with 3D printing guided template assisted radioactive seed implantations in Peking University Third Hospital were included in this study. (125)I seeds with a prescribed dose of 110-180 Gy were impanted. 3D printing templates were designed and produced for 35 cases. The dosimetric parameters: D(90), minimum peripheral dose (mPD), V(100), V(150), V(200), conformal index (CI), external index (EI), and homogeneity index (HI) were compared between pre-and post-plannings. Statistical method was two group of related non-parameters test. Results: The design and production of 35 cases' templates were in place well. Compared with the preoperative planning, the postoperative D(90), V(100), V(150), V(200), mPD, CI, EI and HI differences were 5.57%, 0.34%, 0.33%, -1.20%, 21%, 2.8%, -14.2%, 4.71%, -10.4%. All the included dosimetry parameters changed slightly after surgery compared with before surgery, but the difference was not statistically significant(all P>0.05). Conclusions: The dosimetric parameters of postoperative verification are consistent well with the preoperative planning and have good accuracy, the results could meet the clinical requirements.

Structural insights into repression of the Pneumococcal fatty acid synthesis pathway by repressor FabT and co-repressor acyl-ACP

The Streptococcus pneumoniae fatty acid synthesis (FAS) pathway is globally controlled at the transcriptional level by the repressor FabT and its co-repressor acyl carrier protein (acyl-ACP), the intermediate of phospholipid synthesis. Here, we report the crystal structure of FabT complexed with a 23-bp dsDNA, which indicates that FabT is a weak repressor with low DNA-binding affinity in the absence of acyl-ACP. Modification of ACP with a long-chain fatty acid is necessary for the formation of a stable complex with FabT, mimicked in vitro by cross-linking, which significantly elevates the DNA-binding affinity of FabT. Altogether, we propose a putative working model of gene repression under the double control of FabT and acyl-ACP, elucidating a distinct repression network for Pneumococcus to precisely coordinate FAS.

[Construction of mouse CCR3 gene RNAi lentivirus vector and its expression on mast cells]

Objective:The aim of this study is to screen the targeting chemokine receptor 3-RNA interference (CCR3-RNAi) lentiviral expression vector, infect mouse mast cells,observe the expression of this gene in mast cells and the interference efficiency of the virus vector.The pathogenesis of allergic rhinitis lays the foundation.Method:Three pairs of CCR3-shRNA sequences were constructed,and three pairs of double-stranded shRNA oligo were inserted into shRNA lentiviral vectors to construct three shRNA lentiviral recombinant plasmids.The recombinant vector and virus-packed auxiliary plasmids were co-transfected into 293T cells to obtain lentiviral plasmids.The lentiviral plasmids were then transfected into mouse bone marrow-derived mast cells in vitro and purified. The expression level of CCR3 mRNA in mast cells was verified by qRT-PCR,and the expression level of CCR3 protein in mast cells was detected by Western Blot.Result: It was confirmed by sequencing that the lentiviral vector of CCR3 shRNA was successfully constructed, transfected into 293T cells and packaged with virus. Finally the high purity PDSO19-PL-CCR3 lentiviral plasmid was obtained with a virus titer of 3.7×10⁸TU/ml.The lentiviral plasmid was used to infect mouse mast cells.RT-PCR and Western Blot detection assay showed that CCR3shRNA reduced the expression of CCR3 gene in mouse mast cells at the level of mRNA and protein.Conclusion: The CCR3 gene RNAi lentivirus expression vector was successfully constructed.It was found that it downregulated the expression level of CCR3 gene mRNA and protein in mouse mast cells,which laid the foundation for further research on its role in the pathogenesis of allergic rhinitis.

Structural insights into the catalysis and substrate specificity of cyanobacterial aspartate racemase McyF

L-amino acids represent the most common amino acid form, most notably as protein residues, whereas D-amino acids, despite their rare occurrence, play significant roles in many biological processes. Amino acid racemases are enzymes that catalyze the interconversion of L- and/or D-amino acids. McyF is a pyridoxal 5'-phosphate (PLP) independent amino acid racemase that produces the substrate D-aspartate for the biosynthesis of microcystin in the cyanobacterium Microcystis aeruginosa PCC7806. Here we report the crystal structures of McyF in complex with citrate, L-Asp and D-Asp at 2.35, 2.63 and 2.80 Å, respectively. Structural analyses indicate that McyF and homologs possess highly conserved residues involved in substrate binding and catalysis. In addition, residues Cys87 and Cys195 were clearly assigned to the key catalytic residues of "two bases" that deprotonate D-Asp and L-Asp in a reaction independent of PLP. Further site-directed mutagenesis combined with enzymatic assays revealed that Glu197 also participates in the catalytic reaction. In addition, activity assays proved that McyF could also catalyze the interconversion of L-MeAsp between D-MeAsp, the precursor of another microcystin isoform. These findings provide structural insights into the catalytic mechanism of aspartate racemase and microcystin biosynthesis.

[Comparison of preoperative planning of radioactive seed implantation for pelvic wall recurrent gynecological malignant tumors between 3D-printing non-coplanar template and 3D-printing coplanar template]

Objective: To compare the difference of preoperative planning parameters between 3D-printing non-coplanar template (3D-PNCT) and 3D-printing coplanar template (3D-PCT) in the treatment of pelvic wall recurrent gynecological malignant tumor with radioactive seeds implantation, and to guide the clinical application. Methods: From January 2016 to March 2018, 33 patients with pelvic wall recurrent gynecological malignant tumor were treated with radioactive seeds implantation assisted by 3D-printing template and in Peking University Third Hospital. All patients underwent 3D-PNCT and 3D-PCT preoperative planning. The D(90) of target remained similar for the same patient. The parameters were compared with Wilcoxon test or Kruskal-Wallis test. Results: D(90) was similar between the two groups (P>0.05). The number of inserting needles through intestine and bone in 3D-PNCT group was less than that in 3D-PCT group (0 (0-13), 0 (0-25), Z=-2.941, P<0.05;0 (0-3), 0 (0-25), Z=-2.232, P<0.05). Conclusion: For patients with gynecological malignancies with pelvic recurrence, both of the two peroperative plans could achieve prescription dose, but 3D-PNCT is more safer.

[Analysis of changes in serological factors in the dose-increasing phase of allergic rhinitis rush immunotherapy]

Objective:To observe the changes of serological factors in the dose-increasing phase of allergic rhinitis and to explore the mechanism of short-term rush immunotherapy.Method:The clinical data of 110 patients with allergic rhinitis diagnosed by rush immunotherapy in our hospital were analyzed. According to the results of allergen test（sIgE）, they were divided into simple dust mite allergy group and multiple allergen allergy groups. The serum of the patients were taken before the start of rush immunotherapy and the first day after the end of the dose-increasing phase.Serum total IgE and IgG before and after rush immunotherapy were detected by Beekman specific protein detector. The serum levels of IFN-γ,IL-12,IL-10,IgG1 and IgG4 were measured by ELISA before and after rush immunotherapy. The changes of them were compared and analyzed.Result:①Serum total IgE and IgG were increased after rush immunotherapy, and the change of serum IgG concentration in the simple dust mite allergy group was statistically significant（P<0.05).②The levels of serum IFN-γ, IL-12 and IL-10 increased after rush immunotherapy. The changes of IL-12 and IFN-γ in multiple allergen allergy groups were not significant before and after treatment, while the changes in other groups were statistically significant（P<0.05).③Serum total IgG1 and IgG4 were increased after rush immunotherapy. The changes of serum IgG4 in the simple dust mite allergy group were statistically significant(P<0.05). There was no statistically significant difference in serum IgG1.Conclusion:The dose-increasing phase of rush immunotherapy can stimulate the production of IgG antibodies and the changes of related serological factors in a short period of time, especially in patients with simple dust mite allergy group. It indicates that dose-increasing phase of rush immunotherapy may play a role by regulating immunoglobulin and adjusting the dynamic balance of Th1/Th2 factors.

[Effect of HIF-2α mediated FoxM1 expression on proliferation of pulmonary artery smooth muscle cells in hypoxic rats]

Objective: To investigate the effect of hypoxia-inducible factor 2α (HIF-2α) gene on the expression of Forkhead box M1 (FoxM1) protein in the proliferation of hypoxic rat pulmonary artery smooth muscle cells (PASMC). Methods: HIF-2α overexpression lentiviral vector (LV-HIF-2α) and silencing RNA (siRNA) were constructed and transfected into rat PASMC under normoxia and hypoxia, respectively. The PASMC under normoxia were classified into normoxic control group, normoxia + LV-HIF-2α empty group, normoxia + LV-HIF-2α group; the PASMC under hypoxia were classified into hypoxic control group, hypoxia + siRNA-HIF-2α empty group, hypoxia + siRNA-HIF-2α group. The expression of HIF-2α and its downstream proteins FoxM1, cyclin D1 and Aurora A expressions were detected by Western blot. 5-Ethyny-2'-deoxyuridine (EdU) cell proliferation assay was used to evaluate the effect of overexpression and inhibition of HIF-2α expression on the proliferation of rat PASMC. Results: The expression of HIF-2α in normoxia + LV-HIF-2α group was significantly higher than that in normoxic control group and normoxia+LV-HIF-2α empty group (0.17±0.02 vs 0.09±0.01 and 0.07±0.00), while the expression of HIF-2α in PASMC of hypoxia + siRNA-HIF-2α group was significantly lower than that of hypoxic control group and hypoxia + siRNA-HIF-2α empty group (0.28±0.01 vs 0.35±0.02 and 0.30±0.01) (all P<0.05); the expression of FoxM1 protein, cyclinD1 and cell proliferation-related Aurora A protein in normoxia+LV-HIF-2α group were significantly higher than that in normoxic control group and normoxia+LV-HIF-2α empty group (0.40±0.03 vs 0.24±0.01 and 0.30±0.01, 0.22±0.02 vs 0.09±0.01 and 0.08±0.02, 0.29±0.02 vs 0.04±0.01 and 0.07±0.01, respectively) (all P<0.05); the expressions of FoxM1 protein, cyclinD1 and Aurora A protein in hypoxia + siRNA-HIF-2α group were significantly lower than those in hypoxic control group and hypoxia + siRNA-HIF-2α empty group (0.23±0.01 vs 0.36±0.02 and 0.32±0.01, 0.15±0.01 vs 0.31±0.01 and 0.28±0.03, 0.14±0.02 vs 0.33±0.03 and 0.27±0.02, respectively) (all P<0.05); the positive expression rate of EdU in the normoxic control group was significantly lower than that in the normoxia+LV-HIF-2α group [(30.77±2.43)% vs (55.56±3.01)%], while the hypoxic control group was significantly higher than the hypoxic+siRNA-HIF-2α group [(65.28±3.21)% vs (44.64±2.78)%] (both P<0.05). Conclusion: HIF-2α up-regulates the expression of FoxM1 and promotes the proliferation of pulmonary artery smooth muscle cells in hypoxic rats.

The redefined DNA-binding domain of human xeroderma pigmentosum complementation group A: production, crystallization and structure solution

Human xeroderma pigmentosum complementation group A (XPA) is a scaffold protein that plays significant roles in DNA-damage verification and in recruiting downstream endonucleases to facilitate the repair of DNA lesions in nucleotide-excision repair. XPA98-219 (residues 98-219) has been identified as a DNA-binding domain and has been extensively studied in the last two decades. However, the most recent studies have redefined the DNA-binding domain as XPA98-239 (residues 98-239); it exerts a remarkably higher DNA-binding affinity than XPA98-219 and has a binding affinity that is quite similar to that of the full-length protein. Here, the production, crystallization and structure solution of human XPA98-239 are described. Crystals were obtained using a precipitant composed of 1.8 M ammonium citrate tribasic pH 7.0. Native X-ray diffraction data and zinc single-wavelength anomalous diffraction (SAD) data were collected to 1.93 and 2.06 Å resolution, respectively. The crystals belonged to space group P3, with unit-cell parameters a = 67.1, b = 67.1, c = 35.6 Å, γ = 120.0°. Crystal-content analysis showed the presence of one molecule in the asymmetric unit, corresponding to a Matthews coefficient of 2.65 Å3 Da-1 and a solvent content of 53.6%. The initial phases were solved and the structure model was automatically built by zinc SAD using the AutoSol program. The initial structure model covered 119 of 142 residues in the asymmetric unit, with an Rwork of 22.15% and an Rfree of 25.82%. Compared with a previously obtained truncated solution NMR structure of XPA (residues 98-210), a 19-residue C-terminal extension (residues 211-229, corresponding to 10 of the 20 extra C-terminal residues in the redefined domain for enhanced DNA binding) was contained in this initial model. Refinement of the atomic coordinates of XPA is ongoing.

[Research on immune regulation mechanism of immunotherapy for allergic rhinitis]

Immunotherapy, among all the treatments of allergic rhinitis, is the only one which aims directly at etiological factor.Even though, subcutaneous immunotherapy is a widely used and effective therapeutic method in clinical practice, there is no definite answer in the current research about how it regulates the immune mechanism of allergic rhinitis, that is, how to predict the curative effect according to its objective indicators. In order to have an insight into its clinical role in the immune mechanism of allergic rhinitis,this article will have an overview about it, on the basis of the pertinent medical literature.