Structure of SPH (self-incompatibility protein homologue) proteins: a widespread family of small, highly stable, secreted proteins
SPH (self-incompatibility protein homologue) proteins are a large family of small, disulfide-bonded, secreted proteins, initially found in the self-incompatibility response in the field poppy (Papaver rhoeas), but now known to be widely distributed in plants, many containing multiple members of this protein family. Using the Origami strain of Escherichia coli, we expressed one member of this family, SPH15 from Arabidopsis thaliana, as a folded thioredoxin fusion protein and purified it from the cytosol. The fusion protein was cleaved and characterised by analytical ultracentrifugation, circular dichroism and nuclear magnet...
Source: Biochemical Journal - March 11, 2019 Category: Biochemistry Authors: Rajasekar, K. V., Ji, S., Coulthard, R. J., Ride, J. P., Reynolds, G. L., Winn, P. J., Wheeler, M. J., Hyde, E. I., Smith, L. J. Tags: Research Articles Source Type: research
Aminoglycoside antibiotic resistance conferred by Hpa2 of MDR Acinetobacter baumannii: an unusual adaptation of a common histone acetyltransferase
Antibiotic-resistant bacteria pose the greatest threat to human health. Among the list of such bacteria released by WHO, carbapenem-resistant Acinetobacter baumannii, for which almost no treatment exists, tops the list. A. baumannii is one of the most troublesome ESKAPE pathogens and mechanisms that have facilitated its rise as a successful pathogen are not well studied. Efforts in this direction have resulted in the identification of Hpa2-Ab, an uncharacterized histone acetyltransferase enzyme of GNAT superfamily. Here, we show that Hpa2-Ab confers resistance against aminoglycoside antibiotics using Escherichia coli DH5&a...
Source: Biochemical Journal - March 5, 2019 Category: Biochemistry Authors: Tomar, J. S., Peddinti, R. K., Hosur, R. V. Tags: Research Articles Source Type: research
The lipid head group is the key element for substrate recognition by the P4 ATPase ALA2: a phosphatidylserine flippase
Type IV P-type ATPases (P4 ATPases) are lipid flippases that catalyze phospholipid transport from the exoplasmic to the cytoplasmic leaflet of cellular membranes, but the mechanism by which they recognize and transport phospholipids through the lipid bilayer remains unknown. In the present study, we succeeded in purifying recombinant aminophospholipid ATPase 2 (ALA2), a member of the P4 ATPase subfamily in Arabidopsis thaliana, in complex with the ALA-interacting subunit 5 (ALIS5). The ATP hydrolytic activity of the ALA2–ALIS5 complex was stimulated in a highly specific manner by phosphatidylserine. Small changes in ...
Source: Biochemical Journal - March 5, 2019 Category: Biochemistry Authors: Theorin, L., Faxen, K., Sorensen, D. M., Migotti, R., Dittmar, G., Schiller, J., Daleke, D. L., Palmgren, M., Lopez-Marques, R. L., Günther Pomorski, T. Tags: Research Articles Source Type: research
New insights into niclosamide action: autophagy activation in colorectal cancer
Colorectal cancer is one of the most common forms of cancer in the world, with more than half a million new cases annually. Amongst the most promising new therapies, niclosamide—an FDA-approved drug for treating tapeworm infections—is being assessed in a stage II clinical trial for the treatment of metastatic colorectal cancer. Despite this advanced stage of research, the underlying mechanisms behind its actions remain uncertain. Niclosamide reduces the growth of colorectal cancer cells by targeting several intracellular signalling pathways, including the β-catenin-dependent WNT signalling pathway. In a re...
Source: Biochemical Journal - March 5, 2019 Category: Biochemistry Authors: Newton, P. T. Tags: Commentaries Source Type: research
Signalling circuits that direct early B-cell development
In mammals, the B-cell lineage arises from pluripotent progenitors in the bone marrow. During their development, B-cells undergo lineage specification and commitment, followed by expansion and selection. These processes are mediated by regulated changes in gene expression programmes, rearrangements of immunoglobulin (Ig) genes, and well-timed rounds of proliferation and apoptosis. Many of these processes are initiated by environmental factors including cytokines, chemokines, and cell–cell contacts. Developing B-cells process these environmental cues into stage-specific functions via signalling pathways including the ...
Source: Biochemical Journal - March 5, 2019 Category: Biochemistry Authors: Petkau, G., Turner, M. Tags: Review Articles Source Type: research
Drosophila Hcf regulates the Hippo signaling pathway via association with the histone H3K4 methyltransferase Trr
Control of organ size is a fundamental aspect in biology and plays important roles in development. The Hippo pathway is a conserved signaling cascade that controls tissue and organ size through the regulation of cell proliferation and apoptosis. Here, we report on the roles of Hcf (host cell factor), the Drosophila homolog of Host cell factor 1, in regulating the Hippo signaling pathway. Loss-of-Hcf function causes tissue undergrowth and the down-regulation of Hippo target gene expression. Genetic analysis reveals that Hcf is required for Hippo pathway-mediated overgrowth. Mechanistically, we show that Hcf associates with ...
Source: Biochemical Journal - February 28, 2019 Category: Biochemistry Authors: Nan, Z., Yang, W., Lyu, J., Wang, F., Deng, Q., Xi, Y., Yang, X., Ge, W. Tags: Research Articles Source Type: research
Structural basis for the bypass of the major oxaliplatin-DNA adducts by human DNA polymerase {eta}
Oxaliplatin, together with cisplatin, is among the most important drugs used in cancer chemotherapy. Oxaliplatin, which contains a bulky diaminocyclohexane (DACH) moiety, kills cancer cells mainly by producing (DACH)Pt–GpG intrastrand cross-links that impede transcription. The Pt–GpG tolerance by translesion DNA synthesis (TLS) polymerases contributes to the resistance of tumors to platinum-based chemotherapy. In particular, human DNA polymerase (Pol) readily bypasses Pt–GpG adducts. While many structural studies have addressed how TLS polymerases interact with cisplatin–DNA adducts, a structure of ...
Source: Biochemical Journal - February 28, 2019 Category: Biochemistry Authors: Ouzon-Shubeita, H., Baker, M., Koag, M.-C., Lee, S. Tags: Research Articles Source Type: research
Biochemical and structural investigation of sulfoacetaldehyde reductase from Klebsiella oxytoca
Sulfoacetaldehyde reductase (IsfD) is a member of the short-chain dehydrogenase/reductase (SDR) family, involved in nitrogen assimilation from aminoethylsulfonate (taurine) in certain environmental and human commensal bacteria. IsfD catalyzes the reversible NADPH-dependent reduction of sulfoacetaldehyde, which is generated by transamination of taurine, forming hydroxyethylsulfonate (isethionate) as a waste product. In the present study, the crystal structure of Klebsiella oxytoca IsfD in a ternary complex with NADPH and isethionate was solved at 2.8 Å, revealing residues important for substrate binding. IsfD for...
Source: Biochemical Journal - February 28, 2019 Category: Biochemistry Authors: Zhou, Y., Wei, Y., Lin, L., Xu, T., Ang, E. L., Zhao, H., Yuchi, Z., Zhang, Y. Tags: Research Articles Source Type: research
Substrate-assisted mechanism of catalytic hydrolysis of misaminoacylated tRNA required for protein synthesis fidelity
d-aminoacyl-tRNA-deacylase (DTD) prevents the incorporation of d-amino acids into proteins during translation by hydrolyzing the ester bond between mistakenly attached amino acids and tRNAs. Despite extensive study of this proofreading enzyme, the precise catalytic mechanism remains unknown. Here, a combination of biochemical and computational investigations has enabled the discovery of a new substrate-assisted mechanism of d-Tyr-tRNATyr hydrolysis by Thermus thermophilus DTD. Several functional elements of the substrate, misacylated tRNA, participate in the catalysis. During the hydrolytic reaction, the 2'-OH group of the...
Source: Biochemical Journal - February 28, 2019 Category: Biochemistry Authors: Ilchenko, M. M., Rybak, M. Y., Rayevsky, A. V., Kovalenko, O. P., Dubey, I. Y., Tukalo, M. A. Tags: Research Articles Source Type: research
Regulation of cell migration by {alpha}4 and {alpha}9 integrins
Integrins are heterodimeric transmembrane receptors that play an essential role in enabling cells to sense and bind to extracellular ligands. Activation and clustering of integrins leads to the formation of focal adhesions at the plasma membrane that subsequently initiate signalling pathways to control a broad range of functional endpoints including cell migration, proliferation and survival. The α4 and α9 integrins form a small sub-family of receptors that share some specific ligands and binding partners. Although relatively poorly studied compared with other integrin family members, emerging evidence suggests...
Source: Biochemical Journal - February 28, 2019 Category: Biochemistry Authors: Hight-Warburton, W., Parsons, M. Tags: Review Articles Source Type: research
An ion for an iron: streptococcal metal homeostasis under oxidative stress
The ability of opportunistic pathogens such as Group A Streptococcus (GAS) to transition between mucosal colonisation and invasive disease requires complex systems for adapting to markedly different host environments. The battle to acquire essential trace metals such as manganese and iron from the host is central to pathogenesis. Using a molecular genetic approach, Turner et al. [Biochem. J. (2019) 476, 595–611] show that it is not just individual metal concentrations that are important, but the ratio of iron to manganese within cells. Increasing this ratio by knocking out pmtA, encoding the Fe(II) exporter PmtA, or ...
Source: Biochemical Journal - February 28, 2019 Category: Biochemistry Authors: Jakubovics, N. S. Tags: Commentaries Source Type: research
The metabolite repair enzyme Nit1 is a dual-targeted amidase that disposes of damaged glutathione in Arabidopsis
The tripeptide glutathione (GSH) is implicated in various crucial physiological processes including redox buffering and protection against heavy metal toxicity. GSH is abundant in plants, with reported intracellular concentrations typically in the 1–10 mM range. Various aminotransferases can inadvertently transaminate the amino group of the -glutamyl moiety of GSH to produce deaminated glutathione (dGSH), a metabolite damage product. It was recently reported that an amidase known as Nit1 participates in dGSH breakdown in mammals and yeast. Plants have a hitherto uncharacterized homolog of the Nit1 amidase. We sh...
Source: Biochemical Journal - February 19, 2019 Category: Biochemistry Authors: Niehaus, T. D., Patterson, J. A., Alexander, D. C., Folz, J. S., Pyc, M., MacTavish, B. S., Bruner, S. D., Mullen, R. T., Fiehn, O., Hanson, A. D. Tags: Research Articles Source Type: research
Characterization of the housekeeping sortase from the human pathogen Propionibacterium acnes: first investigation of a class F sortase
Sortase enzymes play an important role in Gram-positive bacteria. They are responsible for the covalent attachment of proteins to the surface of the bacteria and perform this task via a highly sequence-specific transpeptidation reaction. Since these immobilized proteins are often involved in pathogenicity of Gram-positive bacteria, characterization of this type of enzyme is also of medical relevance. Different classes of sortases (A–F) have been found, which recognize characteristic recognition sequences present in substrate proteins. Up to date, sortase A from Staphylococcus aureus, a housekeeping class A sortase, i...
Source: Biochemical Journal - February 19, 2019 Category: Biochemistry Authors: Di Girolamo, S., Puorger, C., Castiglione, M., Vogel, M., Gebleux, R., Briendl, M., Hell, T., Beerli, R. R., Grawunder, U., Lipps, G. Tags: Research Articles Source Type: research
A cyclic peptide reproducing the {alpha}1 helix of VEGF-B binds to VEGFR-1 and VEGFR-2 and inhibits angiogenesis and tumor growth
Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are pivotal regulators of angiogenesis. The VEGF–VEGFR system is therefore an important target of anti-angiogenesis therapy. Based on the X-ray structure of VEGF-B/VEGFR-1 D2, we designed a cyclic peptide (known as VGB1) reproducing the α1 helix and its adjacent region to interfere with signaling through VEGFR-1. Unexpectedly, VGB1 bound VEGFR-2 in addition to VEGFR-1, leading to inhibition of VEGF-stimulated proliferation of human umbilical vein endothelial cells and 4T1 murine mammary carcinoma cells, which express VGEFR-1 and VEGFR-2, a...
Source: Biochemical Journal - February 19, 2019 Category: Biochemistry Authors: Assareh, E., Mehrnejad, F., Mansouri, K., Esmaeili Rastaghi, A. R., Naderi-Manesh, H., Asghari, S. M. Tags: Research Articles Source Type: research
Phosphoglycolate has profound metabolic effects but most likely no role in a metabolic DNA response in cancer cell lines
Repair of a certain type of oxidative DNA damage leads to the release of phosphoglycolate, which is an inhibitor of triose phosphate isomerase and is predicted to indirectly inhibit phosphoglycerate mutase activity. Thus, we hypothesized that phosphoglycolate might play a role in a metabolic DNA damage response. Here, we determined how phosphoglycolate is formed in cells, elucidated its effects on cellular metabolism and tested whether DNA damage repair might release sufficient phosphoglycolate to provoke metabolic effects. Phosphoglycolate concentrations were below 5 µM in wild-type U2OS and HCT116 cells and re...
Source: Biochemical Journal - February 19, 2019 Category: Biochemistry Authors: Gerin, I., Bury, M., Baldin, F., Graff, J., Van Schaftingen, E., Bommer, G. T. Tags: Research Articles Source Type: research
