Essential residues for the enzyme activity of ATP-dependent MurE ligase from Mycobacterium tuberculosis

The emergence of total drug-resistant tuberculosis (TDRTB) has made the discovery of new therapies for tuberculosis urgent. The cytoplasmic enzymes of peptidoglycan biosynthesis have generated renewed interest as attractive targets for the development of new anti-mycobacterials. One of the cytoplasmic enzymes, uridine diphosphate (UDP)-MurNAc-tripeptide ligase (MurE), catalyses the addition of meso-diaminopimelic acid (m-DAP) into peptidoglycan in Mycobacterium tuberculosis coupled to the hydrolysis of ATP. Mutants of M. tuberculosis MurE were generated by replacing K157, E220, D392, R451 with alanine and N449 with aspartate, and truncating the first 24 amino acid residues at the N-terminus of the enzyme. Analysis of the specific activity of these proteins suggested that apart from the 24 Nterminal residues, the other mutated residues are essential for catalysis. Variations in K m values for one or more substrates were observed for all mutants, except the N-terminal truncation mutant, indicating that these residues are involved in binding substrates and form part of the active site structure. These mutant proteins were also tested for their specificity for a wide range of substrates. Interestingly, the mutations K157A, E220A and D392A showed hydrolysis of ATP uncoupled from catalysis. The ATP hydrolysis rate was enhanced by at least partial occupation of the uridine nucleotide dipeptide binding site. This study provides an insight into the residues essential for the catalytic activity and substrate binding of the ATP-dependent MurE ligase. Since ATP-dependent MurE ligase is a novel drug target, the understanding of its function may lead to development of novel inhibitors against resistant forms of M. tuberculosis

A novel rapid-onset high-penetrance plasmacytoma mouse model driven by deregulation of cMYC cooperating with KRAS12V in BALB/c mice

Our goal is to develop a rapid and scalable system for functionally evaluating deregulated genes in multiple myeloma (MM). Here, we forcibly expressed human cMYC and KRAS12V in mouse T2 B cells (IgM+B220+CD38+IgD+) using retroviral transduction and transplanted these cells into lethally irradiated recipient mice. Recipients developed plasmacytomas with short onset (70 days) and high penetrance, whereas neither cMYC nor KRAS12V alone induced disease in recipient mice. Tumor cell morphology and cell surface biomarkers (CD138+B220−IgM−GFP+) indicate a plasma cell neoplasm. Gene set enrichment analysis further confirms that the tumor cells have a plasma cell gene expression signature. Plasmacytoma cells infiltrated multiple loci in the bone marrow, spleen and liver; secreted immunoglobulins; and caused glomerular damage. Our findings therefore demonstrate that deregulated expression of cMYC with KRAS12V in T2 B cells rapidly generates a plasma cell disease in mice, suggesting utility of this model both to elucidate molecular pathogenesis and to validate novel targeted therapies

QGP Susceptibilities from PNJL Model

An improved version of the PNJL model is used to calculate various thermodynamical quantities, {\it viz.}, quark number susceptibility, isospin susceptibility, specific heat, speed of sound and conformal measure. Comparison with Lattice data is found to be encouraging.Comment: 4 pages, 2 figures, poster presented at Quark Matter'0

HDAC Inhibition by LBH589 Affects Phenotype and Function of Human Myeloid Dendritic Cells

LBH589 is a novel pan-HDAC inhibitor which has potent antitumor activity in multiple myeloma and other hematologic malignancies. However, its impact on immune system has not been defined. We here evaluated the effects of LBH589 on human myeloid dendritic cells (DCs) at clinically relevant concentrations. Exposure to LBH589 affected the surface molecule expression on immature and mature DCs, associated with DC maturation (CD83↓), antigen presentation (HLA-ABC↓), and T cell co-stimulation (CD40↓ and CD86↑). LBH589 decreased both protein and polysaccharide antigen uptake capacities by DCs. Importantly, LBH589 impaired DCs function to stimulate antigen-specific immune responses, resulting in the significant reduction of invariant NKT cell (CD1d-restricted) and T cell (MHC-restricted) activation in innate and adaptive immunity. LBH589 also significantly repressed the production of IL-6, IL-10, IL-12p70, IL-23 and TNF-α by TLR3 and TLR4-induced DCs activation, indicating an important role of HDAC activity in immune regulation and inflammation. RelB, a component of NF-κB signaling pathway, was the key component regulated by HDAC inhibition in DCs. Together, our preclinical study demonstrates that LBH589 significantly impairs phenotype and function of DCs, indicating a need for monitoring the immune status in patients receiving HDAC inhibitor therapy. It also provides a rationale to evaluate LBH589 activity for the treatment of inflammation

Planck 2015 results. XX. Constraints on inflation

We present the implications for cosmic inflation of the Planck measurements of the cosmic microwave background (CMB) anisotropies in both temperature and polarization based on the full Planck survey. The Planck full mission temperature data and a first release of polarization data on large angular scales measure the spectral index of curvature perturbations to be n s = 0.968 ± 0.006 and tightly constrain its scale dependence to dn s /dlnk = −0.003 ± 0.007 when combined with the Planck lensing likelihood. When the high-ℓ polarization data is included, the results are consistent and uncertainties are reduced. The upper bound on the tensor-to-scalar ratio is r 0.002 <0.11 (95% CL), consistent with the B-mode polarization constraint r<0.12 (95% CL) obtained from a joint BICEP2/Keck Array and Planck analysis. These results imply that V(ϕ)∝ϕ 2 and natural inflation are now disfavoured compared to models predicting a smaller tensor-to-scalar ratio, such as R 2 inflation. Three independent methods reconstructing the primordial power spectrum are investigated. The Planck data are consistent with adiabatic primordial perturbations. We investigate inflationary models producing an anisotropic modulation of the primordial curvature power spectrum as well as generalized models of inflation not governed by a scalar field with a canonical kinetic term. The 2015 results are consistent with the 2013 analysis based on the nominal mission data

The current status of observational cosmology

Observational cosmology has indeed made very rapid progress in recent years. The ability to quantify the universe has largely improved due to observational constraints coming from structure formation. The transition to precision cosmology has been spearheaded by measurements of the anisotropy in the cosmic microwave background (CMB) over the past decade. Observations of the large scale structure in the distribution of galaxies, high red-shift supernova, have provided the required complementary information. We review the current status of cosmological parameter estimates from joint analysis of CMB anisotropy and large scale structure (LSS) data. We also sound a note of caution on overstating the successes achieved thus far.Comment: 13 pages, 3 figures, Latex style files included, To appear in the proceedings of ICGC-04. Minor rewording in the abstract and introductio

Cosmology with CMB anisotropy

Measurements of CMB anisotropy and, more recently, polarization have played a very important role allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the early universe have also been established -- `acausally' correlated initial perturbations in a flat, statistically isotropic universe, adiabatic nature of primordial density perturbations. Direct evidence for gravitational instability mechanism for structure formation from primordial perturbations has been established. In the next decade, future experiments promise to strengthen these deductions and uncover the remaining crucial signature of inflation -- the primordial gravitational wave background.Comment: Plenary talk at the IXth. International Workshop on High Energy Physics Phenomenology (WHEPP-9), Institute of Physics, Bhubaneshwar, India. Jan 3-14, 2006; To appear in the Proceedings to be published in Pramana; 12 pages, 2 figure