Temperature sensing is essential for the survival of living cells. A major challenge to understand how a biological thermometer processes thermal information optimize cellular functions. Using structural and biochemical approaches, we show that thermosensitive histidine kinase, DesK, from Bacillus subtilis cold-activated through specific interhelical rearrangements in its central four-helix bundle domain. As revealed by crystal structures DesK different functional states, plasticity this...

Leptospira are unique among bacteria based on their helical cell morphology with hook-shaped ends and the presence of periplasmic flagella (PF) pronounced spontaneous supercoiling. The factors that provoke such supercoiling, as well role PF coiling plays in generating characteristic hook-end motility, have not been elucidated. We now identified an abundant protein from pathogen L. interrogans, exposed surface, named it Flagellar-coiling A (FcpA). gene encoding FcpA is highly conserved was...

Two-component systems (TCS) are protein machineries that enable cells to respond input signals. Histidine kinases (HK) the sensory component, transferring information toward downstream response regulators (RR). HKs transfer phosphoryl groups their specific RRs, but also dephosphorylate them, overall ensuring proper signaling. The mechanisms by which discriminate between such disparate directions, yet unknown. We now disclose crystal structures of HK:RR complex DesK:DesR from Bacillus...

ABSTRACT Response regulators are proteins that undergo transient phosphorylation, connecting specific signals to adaptive responses. Remarkably, the molecular mechanism of response regulator activation remains elusive, largely because scarcity structural data on multidomain and histidine kinase/response complexes. We now address this question by using a combination crystallographic functional analyses in vitro vivo , studying DesR its cognate sensor kinase DesK, two-component system controls...

The thermosensor histidine kinase DesK from Bacillus subtilis senses changes in membrane fluidity initiating an adaptive response. Structural have been implicated transmembrane signaling, but direct evidence is still lacking. On the basis of structure-guided mutagenesis, we now propose a mechanism DesK-mediated signal sensing and transduction. data indicate that stabilization/destabilization 2-helix coiled coil, which connects sensory domain to its cytosolic catalytic region, crucial control...

DesK is a sensor histidine kinase (HK) that allows Bacillus subtilis to respond cold shock, triggering the adaptation of membrane fluidity via transcriptional control fatty acid desaturase. It belongs HK family HPK7, which includes nitrogen metabolism regulators NarX/Q and antibiotic LiaS among other important kinases. Structural information on different families still scarce several questions remain, particularly concerning molecular features determine specificity during its catalytic...

Cerulenin is a fungal toxin that inhibits both eukaryotic and prokaryotic ketoacyl-acyl carrier protein synthases or condensing enzymes. It has been used experimentally to treat cancer obesity, potent inhibitor of bacterial growth. Understanding the molecular mechanisms resistance cerulenin similar compounds thus highly relevant for human health. We have previously described Bacillus subtilis cerulenin-resistant strain, expressing point-mutated enzyme FabF (FabF[I108F]) (i.e. with isoleucine...

Spirochete bacteria, including important pathogens, exhibit a distinctive means of swimming via undulations the entire cell. Motility is powered by rotation supercoiled 'endoflagella' that wrap around cell body, confined within periplasmic space. To investigate structural basis flagellar supercoiling, which critical for motility, we determined structure native filaments from spirochete Leptospira integrating high-resolution cryo-electron tomography and X-ray crystallography. We show these...

Mucin O-glycosylation is characterized in cancer by aberrant expression of immature carbohydrate structures (Tn, T, and sialyl-Tn antigens). The UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-T) family enzymes regulate the initial steps mucin could be responsible for altered glycosylation observed cancer. Considering that we recently found ppGalNAc-T6 mRNA expressed breast carcinomas, produced a highly specific monoclonal antibody (MAb T6.3) to assess...

Activation-induced deaminase (AID) initiates mutagenic pathways to diversify the antibody genes during immune responses. The access of AID nucleus is limited by CRM1-mediated nuclear export and an uncharacterized mechanism cytoplasmic retention. Here, we define a conformational motif in that dictates its retention demonstrate translation elongation factor eukaryotic 1 α (eEF1A) necessary for sequestering. independent protein synthesis but dependent on tRNA-free form eEF1A. Inhibiting eEF1A...

Retroviral capsids in their native form Capsid proteins of retroviruses protective lattices around viral RNA molecules. The precise molecular details how individual, full-length capsid assemble to shield the genome; however, are not well understood. Obal et al. and Gres now report high resolution crystal structures full length from Bovine Leukemia Virus HIV-1, respectively. two studies complement each other reveal dynamic nature protein assembly individual interact lattice. findings may have...

Abstract Survivin is recognized as an attractive target in cancer therapy because of its selective overexpression the majority tumors. Upregulated expression this protein correlates with increased tumor grade, recurrence risk and decreased patients survival. In study, we assessed efficacy two survivin‐specific small interfering RNA (siRNA) constructs to inhibit T47D human breast cell growth. After siRNA transfection, cells showed a significant reduction proliferation survival exhibiting...

Phosphorylation carries chemical information in biological systems. In two-component systems (TCSs), the sensor histidine kinase and response regulator are connected through phosphoryl transfer reactions that may be uni- or bidirectional. Directionality enables construction of complex regulatory networks optimize signal propagation ensure forward flow information. We combined x-ray crystallography, hybrid quantum mechanics/molecular mechanics (QM/MM) simulations, systems-integrative kinetic...

Despite being the most abundant class of immunoglobulins in humans and playing central roles adaptive immune response, high-resolution structural data are still lacking for antigen-binding region human isotype A antibodies (IgAs). The crystal structures a Fab fragment IgA1 three different forms now reported. three-dimensional organization is similar to those other classes, but FabA1 seems be more rigid, constrained by hydrophobic core interface between variable constant domains heavy chain...

To identify new molecular markers of bone marrow dissemination in human neuroblastoma (NB), we studied the transcriptome profiles malignant neuroblasts established from MYCN-amplified IGR-N-91 model.This experimental model includes cells derived a subcutaneous stage 4 disease, myocardium (Myoc) and (BM) metastatic cells.Gene expression obtained with Agilent oligo microarrays revealed set 107 differentially expressed genes neuroblasts. This included up-regulated involved chemoresistance, cell...

The spirochete endoflagellum is a unique motility apparatus among bacteria. Despite its critical importance for pathogenesis, the full composition of flagellum remains to be determined. We have recently reported that FcpA novel flagellar protein and major component sheath filament Leptospira. By screening library random transposon mutants in Leptospira biflexa, we found motility-deficient mutant harboring disruption hypothetical gene unknown function. Here, show this encodes surface...

Abstract Mycobacterium tuberculosis is a pathogen with unique cell envelope including very long fatty acids, implicated in bacterial resistance and host immune modulation. FasR TetR-like transcriptional activator that plays central role sensing mycobacterial long-chain acids regulating lipid biosynthesis. Here we disclose crystal structures of M. complex acyl effector ligands DNA, uncovering its molecular sensory switching mechanisms. A tunnel traverses the entire effector-binding domain,...

Mucins participate in cancer progression by regulating cell growth, adhesion, signaling, apoptosis or chemo-resistance to drugs. The secreted mucin MUC5B, the major component of respiratory tract mucus, is aberrantly expressed breast cancer, where it could constitute a biomarker. In this study we evaluated role MUC5B gene silencing expression with short hairpin RNA on MCF-7 cells. We found that MUC5B-silenced cells have reduced capacity grow, adhere and form colonies. Interestingly,...

Polypeptide GalNAc-transferases (GalNAc-Ts) constitute a family of 20 human glycosyltransferases (comprising 9 subfamilies), which initiate mucin-type O-glycosylation. The O-glycoproteome is thought to be differentially regulated via the different substrate specificities and expression patterns each GalNAc-T isoforms. Here, we present comprehensive in vitro analysis peptide specificity GalNAc-T13, showing that it essentially overlaps with ubiquitous expressed GalNAc-T1 isoform found same...

The protein FcpA is a unique component of the flagellar filament spirochete bacteria belonging to genus Leptospira . Although it plays an essential role in translational motility and pathogenicity, no structures homologues are currently available PDB. Its three-dimensional structure will unveil novel mechanisms that render pathogenic particularly efficient at invading disseminating within their hosts, causing leptospirosis humans animals. from L. interrogans was purified crystallized, but...