Domain Organization and Active Site Architecture of a Polyketide Synthase C-methyltransferase.

Polyketide metabolites produced by modular type I polyketide synthases (PKS) acquire their chemical diversity through the variety of catalytic domains within modules of the pathway. Methyltransferases are among the least characterized of the catalytic domains common to PKS systems. We determined the domain boundaries and characterized the activity of a PKS C-methyltransferase (C-MT) from the curacin A biosynthetic pathway.

Carboxylate Surrogates Enhance the Antimycobacterial Activity of UDP-Galactopyranose Mutase Probes.

Uridine diphosphate galactopyranose mutase (UGM also known as Glf) is a biosynthetic enzyme required for construction of the galactan, an essential mycobacterial cell envelope polysaccharide. Our group previously identified two distinct classes of UGM inhibitors; each possesses a carboxylate moiety that is crucial for potency yet likely detrimental for cell permeability. To enhance the antimycobacterial potency, we sought to replace the carboxylate with a functional group mimic-an N-acylsulfonamide group.

Structures of a Nonribosomal Peptide Synthetase Module Bound to MbtH-like Proteins Support a Highly Dynamic Domain Architecture.

Nonribosomal peptide synthetases (NRPSs) produce a wide variety of peptide natural products. During synthesis, the multidomain NRPSs act as an assembly line, passing the growing product from one module to the next. Each module generally consists of an integrated peptidyl carrier protein, an amino acid-loading adenylation domain, and a condensation domain that catalyzes peptide bond formation.

Structure of the Essential FadD32 Enzyme: A Promising Drug Target for Treating Tuberculosis.

Mycolic acids are indispensible lipids of (), the causative agent of tuberculosis (TB), and contribute to the distinctive architecture and impermeability of the mycobacterial cell envelope. FadD32 plays a pivotal role in mycolic acid biosynthesis by functionally linking fatty acid synthase (FAS) and polyketide synthase (PKS) biosynthetic pathways. FadD32, a fatty acyl-AMP ligase (FAAL), represents one of the best genetically and chemically validated new TB drug targets.

2-Aryl-8-aza-3-deazaadenosine analogues of 5'-O-[N-(salicyl)sulfamoyl]adenosine: Nucleoside antibiotics that block siderophore biosynthesis in Mycobacterium tuberculosis.

A series of 5'-O-[N-(salicyl)sulfamoyl]-2-aryl-8-aza-3-deazaadenosines were designed to block mycobactin biosynthesis in Mycobacterium tuberculosis (Mtb) through inhibition of the essential adenylating enzyme MbtA. The synthesis of the 2-aryl-8-aza-3-deazaadenosine nucleosides featured sequential copper-free palladium-catalyzed Sonogashira coupling of a precursor 4-cyano-5-iodo-1,2,3-triazolonucleoside with terminal alkynes and a Minakawa-Matsuda annulation reaction. These modified nucleosides were shown to inhibit MbtA with apparent Ki values ranging from 6.

Recent Advances in Resting-State Electroencephalography Biomarkers for Autism Spectrum Disorder-A Review of Methodological and Clinical Challenges.

Background: Electroencephalography (EEG) has been used for almost a century to identify seizure-related disorders in humans, typically through expert interpretation of multichannel recordings. Attempts have been made to quantify EEG through frequency analyses and graphic representations. These "traditional" quantitative EEG analysis methods were limited in their ability to analyze complex and multivariate data and have not been generally accepted in clinical settings.

Synthesis and pharmacological evaluation of nucleoside prodrugs designed to target siderophore biosynthesis in Mycobacterium tuberculosis.

The nucleoside antibiotic, 5'-O-[N-(salicyl)sulfamoyl]adenosine (1), possesses potent whole-cell activity against Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis (TB). This compound is also active in vivo, but suffers from poor drug disposition properties that result in poor bioavailability and rapid clearance. The synthesis and evaluation of a systematic series of lipophilic ester prodrugs containing linear and α-branched alkanoyl groups from two to twelve carbons at the 3'-position of a 2'-fluorinated analog of 1 is reported with the goal to improve oral bioavailability.

Measurement of Nonribosomal Peptide Synthetase Adenylation Domain Activity Using a Continuous Hydroxylamine Release Assay.

Adenylation is a crucial enzymatic process in the biosynthesis of nonribosomal peptide synthetase (NRPS) derived natural products. Adenylation domains are considered the gatekeepers of NRPSs since they select, activate, and load the carboxylic acid substrate onto a downstream peptidyl carrier protein (PCP) domain of the NRPS. We describe a coupled continuous kinetic assay for NRPS adenylation domains that substitutes the PCP domain with hydroxylamine as the acceptor molecule.

Structures of two distinct conformations of holo-non-ribosomal peptide synthetases.

Many important natural products are produced by multidomain non-ribosomal peptide synthetases (NRPSs). During synthesis, intermediates are covalently bound to integrated carrier domains and transported to neighbouring catalytic domains in an assembly line fashion. Understanding the structural basis for catalysis with non-ribosomal peptide synthetases will facilitate bioengineering to create novel products.

An Update on Maternal Hydration Strategies for Amniotic Fluid Improvement in Isolated Oligohydramnios and Normohydramnios: Evidence from a Systematic Review of Literature and Meta-Analysis.

Objective: Several trials aimed at evaluating the efficacy of maternal hydration (MH) in increasing amniotic-fluid-volume (AFV) in pregnancies with isolated oligohydramnios or normohydramnos have been conducted. Unfortunately, no evidences support this intervention in routine-clinical-practice. The aim of this systematic-literature-review and meta-analysis was to collect all data regarding proposed strategies and their efficacy in relation to each clinical condition for which MH-therapy was performed with the aim of increasing amniotic-fluid (AF) and improving perinatal outcomes.

Unsaturated Lipid Assimilation by Mycobacteria Requires Auxiliary cis-trans Enoyl CoA Isomerase.

Mycobacterium tuberculosis (Mtb) can survive in hypoxic necrotic tissue by assimilating energy from host-derived fatty acids. While the expanded repertoire of β-oxidation auxiliary enzymes is considered crucial for Mtb adaptability, delineating their functional relevance has been challenging. Here, we show that the Mtb fatty acid degradation (FadAB) complex cannot selectively break down cis fatty acyl substrates.

Polyketide Quinones Are Alternate Intermediate Electron Carriers during Mycobacterial Respiration in Oxygen-Deficient Niches.

Mycobacterium tuberculosis (Mtb) adaptation to hypoxia is considered crucial to its prolonged latent persistence in humans. Mtb lesions are known to contain physiologically heterogeneous microenvironments that bring about differential responses from bacteria. Here we exploit metabolic variability within biofilm cells to identify alternate respiratory polyketide quinones (PkQs) from both Mycobacterium smegmatis (Msmeg) and Mtb.

"Give Sorrow Words": Working With Bereavement in Senior Residential Settings.

Bereavement and its consequent grief are frequent in senior residential settings. Failure to manage grief appropriately can have serious medical consequences, principally clinical depression. Focused talk with a grieving person can help ease the pain of grief; it can also help prevent complications that often lead to depression.

Mycobacterium tuberculosis IMPDH in Complexes with Substrates, Products and Antitubercular Compounds.

Tuberculosis (TB) remains a worldwide problem and the need for new drugs is increasingly more urgent with the emergence of multidrug- and extensively-drug resistant TB. Inosine 5'-monophosphate dehydrogenase 2 (IMPDH2) from Mycobacterium tuberculosis (Mtb) is an attractive drug target. The enzyme catalyzes the conversion of inosine 5'-monophosphate into xanthosine 5'-monophosphate with the concomitant reduction of NAD+ to NADH.

Tylosin polyketide synthase module 3: stereospecificity, stereoselectivity and steady-state kinetic analysis of β-processing domains diffusible, synthetic substrates.

Polyketide synthase (PKS) β-processing domains are responsible for much of the stereochemical complexity of polyketide natural products. Although the importance of β-processing domains has been well noted and significantly explored, key stereochemical details pertaining to cryptic stereochemistry and the impact of remote stereogenic centers have yet to be fully discerned. To uncover the inner workings of ketoreductases (KR) and dehydratases (DH) from the tylosin pathway a didomain composed of TylDH3-KR3 was recombinantly expressed and interrogated with full-length tetraketide substrates to probe the impact of vicinal and distal stereochemistry.

Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System.

The Mitsunobu reaction is renowned for its mild reaction conditions and broad substrate tolerance, but has limited utility in process chemistry and industrial applications due to poor atom economy and the generation of stoichiometric phosphine oxide and hydrazine by-products that complicate purification. A catalytic Mitsunobu reaction using innocuous reagents to recycle these by-products would overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1-phenylphospholane) employing phenylsilane to recycle the catalyst.

Targeting Mycobacterium tuberculosis Biotin Protein Ligase (MtBPL) with Nucleoside-Based Bisubstrate Adenylation Inhibitors.

Mycobacterium tuberculosis (Mtb), responsible for both latent and symptomatic tuberculosis (TB), remains the second leading cause of mortality among infectious diseases worldwide. Mycobacterial biotin protein ligase (MtBPL) is an essential enzyme in Mtb and regulates lipid metabolism through the post-translational biotinylation of acyl coenzyme A carboxylases. We report the synthesis and evaluation of a systematic series of potent nucleoside-based inhibitors of MtBPL that contain modifications to the ribofuranosyl ring of the nucleoside.

Synthesis and Pharmacokinetic Evaluation of Siderophore Biosynthesis Inhibitors for Mycobacterium tuberculosis.

MbtA catalyzes the first committed biosynthetic step of the mycobactins, which are important virulence factors associated with iron acquisition in Mycobacterium tuberculosis. MbtA is a validated therapeutic target for antitubercular drug development. 5'-O-[N-(Salicyl)sulfamoyl]adenosine (1) is a bisubstrate inhibitor of MbtA and exhibits exceptionally potent biochemical and antitubercular activity.

The Role of Human Papillomavirus Genotyping in Cervical Cancer Screening: A Large-Scale Evaluation of the cobas HPV Test.

Background: The cobas HPV Test ("cobas"; Roche Molecular Systems) detects HPV16 and HPV18 individually, and a pool of 12 other high-risk (HR) HPV types. The test is approved for (i) atypical squamous cells of undetermined significance (ASC-US) triage to determine need for colposcopy, (ii) combined screening with cytology ("cotesting"), and (iii) primary HPV screening.

Methods: To assess the possible value of HPV16/18 typing, >17,000 specimens from a longitudinal cohort study of initially HPV-positive women (HC2, Qiagen) were retested with cobas.

Fragment-based exploration of binding site flexibility in Mycobacterium tuberculosis BioA.

The PLP-dependent transaminase (BioA) of Mycobacterium tuberculosis and other pathogens that catalyzes the second step of biotin biosynthesis is a now well-validated target for antibacterial development. Fragment screening by differential scanning fluorimetry has been performed to discover new chemical scaffolds and promote optimization of existing inhibitors. Calorimetry confirms binding of six molecules with high ligand efficiency.