A Fluorogenic Disaccharide Substrate for α-Mannosidases Enables High-Throughput Screening and Identification of an Inhibitor of the GH92 Virulence Factor from Streptococcus pneumoniae.

Trimming of host glycans is a mechanism that is broadly employed by both commensal and pathogenic microflora to enable colonization. Host glycan trimming by the opportunistic Gram-positive bacterium Streptococcus pneumoniae has been demonstrated to be an important mechanism of virulence. While S. pneumoniae employs a multitude of glycan processing enzymes, the exo-mannosidase SpGH92 has been shown to be an important virulence factor. Accordingly, SpGH92 is hypothesized to be a target for much-needed new treatments of S. pneumoniae infection. Here we report the synthesis of 4-methylumbelliferyl α-d-mannopyranosyl-(1→2)-ß-d-mannopyranoside (Manα1,2Manß-4MU) as a fluorogenic disaccharide substrate and development of an assay for SpGH92 that overcomes its requirement for +1 binding site occupancy. We miniaturize our in vitro assay and apply it to a high-throughput screen of >65 000 compounds, identifying a single inhibitory chemotype, LIPS-343. We further show that Manα1,2Manß-4MU is also a substrate of the human Golgi-localized α-mannosidase MAN1A1, suggesting that this substrate should be useful for assessing the activity of this and other mammalian α-mannosidases.

Outcomes After Hip Arthroscopy Show No Differences Between Sexes: A Systematic Review.

PURPOSE: To assess differences in postoperative outcomes between male and female patients following hip arthroscopy. METHODS: A systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Medline, Embase, Cochrane, and PubMed databases were searched. Key words included "hip," "arthroscopy," "outcome," "gender difference," "sex difference," "gender," and "patient-reported outcome." Studies were included that reported sex-specific analysis of outcomes following primary hip arthroscopy with minimum 2-year follow-up. Methodological Index for Non-Randomized Studies criteria were applied to each study. Data collected included patient-reported outcome measures (PROMs), complications, rates of revision arthroscopy (RA), and conversion to total hip arthroplasty (THA). Forest plots were generated for the most frequently reported PROMs, RA, and THA rates. RESULTS: In total, 38 studies met the inclusion criteria, with 40,194 (57% female) hips included. The most common indications for hip arthroscopy were femoroacetabular impingement and labral tears. Eighteen studies reported PROMs, with no clear trend towards sex differences. Eleven studies reported on RA rates, with 4 showing a significantly greater rate of RA in female patients. Seventeen studies reported on conversion to THA, with an overall conversion rate of 9.64%. There were no clear sex differences in conversion to THA. CONCLUSIONS: There was no difference between sexes for postoperative PROM scores. Male patients were less likely to reach the MCID for the HOS-SSS than female patients in the majority of studies, and there were no sex differences for PASS rates. There were no significant differences between sexes in revision arthroscopy rates and conversion to total hip arthroplasty. LEVEL OF EVIDENCE: Level IV, systematic review of Level II, III and IV studies.

Bicyclic Picomolar OGA Inhibitors Enable Chemoproteomic Mapping of Its Endogenous Post-translational Modifications.

Owing to its roles in human health and disease, the modification of nuclear, cytoplasmic, and mitochondrial proteins with O-linked N-acetylglucosamine residues (O-GlcNAc) has emerged as a topic of great interest. Despite the presence of O-GlcNAc on hundreds of proteins within cells, only two enzymes regulate this modification. One of these enzymes is O-GlcNAcase (OGA), a dimeric glycoside hydrolase that has a deep active site cleft in which diverse substrates are accommodated. Chemical tools to control OGA are emerging as essential resources for helping to decode the biochemical and cellular functions of the O-GlcNAc pathway. Here we describe rationally designed bicyclic thiazolidine inhibitors that exhibit superb selectivity and picomolar inhibition of human OGA. Structures of these inhibitors in complex with human OGA reveal the basis for their exceptional potency and show that they extend out of the enzyme active site cleft. Leveraging this structure, we create a high affinity chemoproteomic probe that enables simple one-step purification of endogenous OGA from brain and targeted proteomic mapping of its post-translational modifications. These data uncover a range of new modifications, including some that are less-known, such as O-ubiquitination and N-formylation. We expect that these inhibitors and chemoproteomics probes will prove useful as fundamental tools to decipher the mechanisms by which OGA is regulated and directed to its diverse cellular substrates. Moreover, the inhibitors and structures described here lay out a blueprint that will enable the creation of chemical probes and tools to interrogate OGA and other carbohydrate active enzymes.

Synthesis, conformational analysis and glycosidase inhibition of bicyclic nojirimycin C-glycosides based on an octahydrofuro[3,2-b]pyridine motif.

A set of bicyclic iminosugar C-glycosides, based on an octahydrofuro[3,2-b]pyridine motif, has been synthesized from a C-allyl iminosugar exploiting a debenzylative iodocycloetherification and an iodine nucleophilic displacement as the key steps. The halogen allowed the introduction of a range of aglycon moieties of different sizes bearing several functionalities such as alcohol, amine, amide and triazole. In these carbohydrate mimics the fused THF ring forces the piperidine to adopt a flattened 4C1 conformation according to NMR and DFT calculations studies. In their deprotected form, these bicycles were assayed on a panel of 23 glycosidases. The iminosugars displaying hydrophobic aglycon moieties proved to be superior glycosidase inhibitors, leading to a low micromolar inhibition of human lysosome ß-glucosidase (compound 11; IC50 = 2.7 µM) and rice α-glucosidase (compound 10; IC50 = 7.7 µM). Finally, the loose structural analogy of these derivatives with Thiamet G, a potent OGA bicyclic inhibitor, was illustrated by the weak OGA inhibitory activity (Ki = 140 µM) of iminosugar 5.

Selective Fluorogenic ß-Glucocerebrosidase Substrates for Convenient Analysis of Enzyme Activity in Cell and Tissue Homogenates.

Within mammals, there are often several functionally related glycoside hydrolases, which makes monitoring their activities problematic. This problem is particularly acute for the enzyme ß-glucocerebrosidase (GCase), the malfunction of which is a key driver of Gaucher's disease (GD) and a major risk factor for Parkinson's disease (PD). Humans harbor two other functionally related ß-glucosidases known as GBA2 and GBA3, and the currently used fluorogenic substrates are not selective, which has driven the use of complicated subtractive assays involving the use of detergents and inhibitors. Here we describe the preparation of fluorogenic substrates based on the widely used nonselective substrate resorufin ß-d-glucopyranoside. Using recombinant enzymes, we show that these substrates are highly selective for GCase. We also demonstrate their value through the analysis of GCase activity in brain tissue homogenates from transgenic mice expressing mutant human GCase and patient fibroblasts expressing mutant GCase. This approach simplifies the analysis of cell and tissue homogenates and should facilitate the analysis of clinical and laboratory tissues and samples.