Understanding the structural basis of the binding specificity of c-di-AMP to M. smegmatis RecA using computational biology approach.

Mycobacterium tuberculosis RecA (MtRecA), a protein involved in DNA repair, homologous recombination and SOS pathway, contributes to the development of multidrug resistance. ATP binding-site in RecA has been a drug target to disable RecA dependent DNA repair. For the first time, experiments have shown the existence and binding of c-di-AMP to a novel allosteric site in the C-terminal-Domain (CTD) of Mycobacterium smegmatis RecA (MsRecA), a close homolog of MtRecA. In addition, it was observed that the c-di-AMP was not binding to Escherichia coli RecA (EcRecA). This article analyses the possible interactions of the three RecA homologs with the various c-di-AMP conformations to gain insights into the structural basis of the natural preference of c-di-AMP to MsRecA and not to EcRecA, using the structural biology tools. The comparative analysis, based on amino acid composition, homology, motifs, residue types, docking, molecular dynamics simulations and binding free energy calculations, indeed, conclusively indicates strong binding of c-di-AMP to MsRecA. Having very similar results as MsRecA, it is highly plausible for c-di-AMP to strongly bind MtRecA as well. These insights from the in-silico studies adds a new therapeutic approach against TB through design and development of novel allosteric inhibitors for the first time against MtRecA.Communicated by Ramaswamy H. Sarma.

How Effective is the Use of Molecular Testing in Preoperative Decision Making for Management of Indeterminate Thyroid Nodules?

INTRODUCTION: We performed Thyroseq v2 molecular testing on indeterminate thyroid nodules and evaluated whether they underwent a management change from the standard of thyroid lobectomy. METHODS: We conducted a retrospective analysis of all indeterminate thyroid nodules that underwent Thyroseq v2 molecular testing from 2014 to 2019 at a large academic center. Pathology was reviewed by thyroid cytopathologists. Thyroseq results were reported benign (malignancy probability less than 10%) or suspicious (malignancy probability greater than 30%). The primary endpoint was a management change from a diagnostic lobectomy. RESULTS: A total of 142 nodules were included: 113 (80%) Bethesda III and 29 (20%) Bethesda IV. Seventy-three nodules underwent surgical management and 69 did not. We noted a change in management in 64% (91/142) of nodules. Patients who underwent a change in management to no surgery had a significantly higher rate of benign Thyroseq result than those without a change (75.8% vs. 49.0%, p = 0.001). On logistic regression analysis, a benign Thyroseq result was a positive independent predictor of a change to no surgery (OR 3.87, 95% CI 1.69-8.89). Nodule size, multiple nodules, compressive symptoms, and history of hypothyroidism were not significant. Of the 91 patients who underwent a management change, 71% (65/91) did not undergo surgery. On follow-up (average 985 ± 615 days), 12% (8/65) of those nodules were growing or developed suspicious features requiring surgery. CONCLUSIONS: Molecular testing helped avoid surgery in almost half our population with indeterminate thyroid nodules, and benign results may help avoid surgery in asymptomatic patients with indeterminate thyroid nodules.

Vancomycin as an Antibacterial Agent Capped with Silver Nanoparticles: An Experimental Potential Analysis.

For the treatment of various infections, a variety of antimicrobial drugs are formulated. Nevertheless, many bacterial infections now exhibit antibiotic resistance due to the widespread utilization antibiotics. Methicillin-resistant among the most dangerous multidrug-resistant bacteria is Staphylococcus aureus (MRSA). Vancomycin became a viable therapy option due to MRSA resistance to methicillin medicines. One of the well-informed antibacterial compounds with wideband antibacterial activity is silver nanoparticles (AgNPs). AgNPs are thus suitable candidates for usage in conjunction alongside vancomycin to increase its antibacterial effect. The goal of the present research work is to boost the antibacterial potency of the glycopeptide antibiotic vancomycin towards Gram-positive (Staphylococcus aureus) but also Gram-negative (Escherichia coli) bacteria. The chemical reduction approach is used to create a colloidal solution of silver nanoparticles utilizing silver nitrate as a precursor in the environment of the ionic surfactant trisodium citrate that serves as covering including reducing reagent. Vancomycin was used to functionalize the synthesized nanoparticles and create the nanodrug complex (Van@AgNPs). The synergistic antibacterial potential of silver nanoparticles coated with vancomycin on both test pathogens was investigated using the agar well diffusion technique. The antibacterial potency for both classes of bacteria has significantly increased, according to the well diffusion test. It has been noted that this improvement is synergistic instead of additive.