Crystal structure of CmABCB1 multi-drug exporter in lipidic mesophase revealed by LCP-SFX

がんの多剤排出の原因となっているABCトランスポーターの立体構造をSACLAのX線自由電子レーザーを用いて決定. 京都大学プレスリリース. 2021-12-23.CmABCB1 is a Cyanidioschyzon merolae homolog of human ABCB1, a well known ATP-binding cassette (ABC) transporter responsible for multi-drug resistance in various cancers. Three-dimensional structures of ABCB1 homologs have revealed the snapshots of inward- and outward-facing states of the transporters in action. However, sufficient information to establish the sequential movements of the open–close cycles of the alternating-access model is still lacking. Serial femtosecond crystallography (SFX) using X-ray free-electron lasers has proven its worth in determining novel structures and recording sequential conformational changes of proteins at room temperature, especially for medically important membrane proteins, but it has never been applied to ABC transporters. In this study, 7.7 mono­acyl­glycerol with cholesterol as the host lipid was used and obtained well diffracting microcrystals of the 130 kDa CmABCB1 dimer. Successful SFX experiments were performed by adjusting the viscosity of the crystal suspension of the sponge phase with hy­droxy­propyl methyl­cellulose and using the high-viscosity sample injector for data collection at the SACLA beamline. An outward-facing structure of CmABCB1 at a maximum resolution of 2.22 Å is reported, determined by SFX experiments with crystals formed in the lipidic cubic phase (LCP-SFX), which has never been applied to ABC transporters. In the type I crystal, CmABCB1 dimers interact with adjacent molecules via not only the nucleotide-binding domains but also the transmembrane domains (TMDs); such an interaction was not observed in the previous type II crystal. Although most parts of the structure are similar to those in the previous type II structure, the substrate-exit region of the TMD adopts a different configuration in the type I structure. This difference between the two types of structures reflects the flexibility of the substrate-exit region of CmABCB1, which might be essential for the smooth release of various substrates from the transporter

Utility of robot‐assisted radical cystectomy with intracorporeal urinary diversion for muscle‐invasive bladder cancer

Radical cystectomy remains the gold standard for treatment of muscle‐invasive bladder cancer. Robot‐assisted radical cystectomy has technical advantages over laparoscopic radical cystectomy and has emerged as an alternative to open radical cystectomy. Despite the advancements in robotic surgery, experience with total intracorporeal reconstruction of urinary diversion remains limited. Most surgeons have carried out the hybrid approach of robot‐assisted radical cystectomy and extracorporeal reconstruction of urinary diversion, as intracorporeal reconstruction of urinary diversion remains technically challenging. However, intracorporeal reconstruction of urinary diversion might potentially proffer additional benefits, such as decreased fluid loss, reduction in estimated blood loss and a quicker return of bowel function. The adoption of intracorporeal ileal neobladder reconstruction has hitherto been limited to high‐volume academic institutions. In the present review, we compare the totally intracorporeal robot‐assisted radical cystectomy approach with open radical cystectomy and robot‐assisted radical cystectomy + extracorporeal reconstruction of urinary diversion in muscle‐invasive bladder cancer patients

A prospective compound screening contest identified broader inhibitors for Sirtuin 1

Potential inhibitors of a target biomolecule, NAD-dependent deacetylase Sirtuin 1, were identified by a contest-based approach, in which participants were asked to propose a prioritized list of 400 compounds from a designated compound library containing 2.5 million compounds using in silico methods and scoring. Our aim was to identify target enzyme inhibitors and to benchmark computer-aided drug discovery methods under the same experimental conditions. Collecting compound lists derived from various methods is advantageous for aggregating compounds with structurally diversified properties compared with the use of a single method. The inhibitory action on Sirtuin 1 of approximately half of the proposed compounds was experimentally accessed. Ultimately, seven structurally diverse compounds were identified

Case of extragonadal germ cell tumor mimicking left adrenal tumor

A 30-year-old man presented to his previous physician with left abdominal pain. Computed tomography revealed a left retroperitoneal mass with calcification, measuring 15 × 9 × 6 cm, and the patient was referred to our hospital for further examination. Based on the endocrinologic examination and magnetic resonance imaging results, the patient was diagnosed with a nonfunctional left adrenal tumor, and laparoscopic left adrenalectomy was performed. Histopathology revealed well-defined boundaries between the tumor and the left adrenal gland, and the tumor was diagnosed as a non-seminoma consisting mainly of an immature teratoma with germ cell neoplasm in situ

Endoscopic combined intrarenal surgery for renal allograft lithiasis using “sheath-connection technique”: A case report

A 66-year-old man was diagnosed with renal allograft lithiasis. Although retrograde intrarenal surgery was attempted, a ureteral access sheath (UAS) was difficult to insert. Subsequently, we planned the endoscopic combined intrarenal surgery (ECIRS) using the “Sheath-connection technique.” We indwelled the two UAS anterogradely and retrogradely, unified them at the bladder and the junction of the two UAS was passed through the ureterovesical junction. We successfully performed ECIRS

Near-Infrared-Light-Activatable Proximity Labeling of Bead-Binding Proteins

Photocatalytic proximity labeling has recently undergone significant advances as a valuable tool for understanding protein–protein and cell–cell interactions. This paper reports the first photocatalytic protein-labeling approach in which the reaction can be controlled using near-infrared (NIR) light (810 nm). Magnetic affinity beads with encapsulated sulfur-substituted silicon (IV) phthalocyanine, which produces singlet oxygen upon NIR irradiation, were prepared. We have developed a method in which the histidine residues of proteins bound to the ligands on the beads are selectively oxidized and labeled by the nucleophilic labeling reagent while minimizing nonspecific adsorption to the dye. Beads with aryl sulfamide, lactose, or CZC-8004 ligands immobilized on their surface can be used to label proteins that bind these ligands, as well as their protein–protein interaction partners

Switching of Photocatalytic Tyrosine/Histidine Labeling and Application to Photocatalytic Proximity Labeling

Weak and transient protein interactions are involved in dynamic biological responses and are an important research subject; however, methods to elucidate such interactions are lacking. Proximity labeling is a promising technique for labeling transient ligand–binding proteins and protein–protein interaction partners of analytes via an irreversible covalent bond. Expanding chemical tools for proximity labeling is required to analyze the interactome. We developed several photocatalytic proximity-labeling reactions mediated by two different mechanisms. We found that numerous dye molecules can function as catalysts for protein labeling. We also identified catalysts that selectively modify tyrosine and histidine residues and evaluated their mechanisms. Model experiments using HaloTag were performed to demonstrate photocatalytic proximity labeling. We found that both ATTO465, which catalyzes labeling by a single electron transfer, and BODIPY, which catalyzes labeling by singlet oxygen, catalyze proximity labeling in cells