Evidence for a Functional O-Linked N-Acetylglucosamine (O-GlcNAc) System in the Thermophilic Bacterium Thermobaculum terrenum

Post-translational modification of proteins is a ubiquitous mechanism of signal transduction in all kingdoms of life. One such modification is addition of O-linked N-acetylglucosamine to serine or threonine residues, known as O-GlcNAcylation. This unusual type of glycosylation is thought to be restricted to nucleocytoplasmic proteins of eukaryotes and is mediated by a pair of O-GlcNAc-transferase and O-GlcNAc hydrolase enzymes operating on a large number of substrate proteins. Protein O-GlcNAcylation is responsive to glucose and flux through the hexosamine biosynthetic pathway. Thus, a close relationship is thought to exist between the level of O-GlcNAc proteins within and the general metabolic state of the cell. Although isolated apparent orthologues of these enzymes are present in bacterial genomes, their biological functions remain largely unexplored. It is possible that understanding the function of these proteins will allow development of reductionist models to uncover the principles of O-GlcNAc signaling. Here, we identify orthologues of both O-GlcNAc cycling enzymes in the genome of the thermophilic eubacterium Thermobaculum terrenum. The O-GlcNAcase and O-GlcNAc-transferase are co-expressed and, like their mammalian orthologues, localize to the cytoplasm. The O-GlcNAcase orthologue possesses activity against O-GlcNAc proteins and model substrates. We describe crystal structures of both enzymes, including an O-GlcNAcase·peptide complex, showing conservation of active sites with the human orthologues. Although in vitro activity of the O-GlcNAc-transferase could not be detected, treatment of T. terrenum with an O-GlcNAc-transferase inhibitor led to inhibition of growth. T. terrenum may be the first example of a bacterium possessing a functional O-GlcNAc system.     

Membrane association with multiple calcium ions: vitamin-K-dependent proteins, annexins and pentraxins.

Peripheral membrane association with high calcium stoichiometry is shared by three families of proteins: annexins, pentraxins and vitamin-K-dependent proteins. Recent crystal structure determinations, biophysical studies of membrane binding and analyses of protein electrostatic properties offer striking and different concepts for membrane association by each of these protein families.     

Intraspecific killing among Leopards (Panthera pardus) in Iran (Mammalia: Felidae)

Intraspecific aggression is one of the most common causes of death in leopards. Here, we report four cases of intraspecific killing amongst Persian Leopards (Panthera pardus saxicolor) in Iran. A young male leopard was found on 7 June 2008 which, according to camera trap images, had been killed by an adult male over a Red Deer (Cervus elaphus) kill, with trauma to his neck in Dorfak No-Hunting Area. A young female that had been fitted with a satellite GPS collar on 6 December 2015 in Tandoureh National Park died on 29 January 2016 at a site where an Urial Sheep (Ovis orientalis) ram had been freshly killed. Necropsy results, footprints at the scene of death and camera trap footage all supported the deduction that the animal was killed by a larger female leopard at the kill site. On 13 January 2017, a young, partially eaten female leopard was found with double puncture on the side of her throat. Finally, a rehabilitated adult female fitted with a satellite GPS collar found on 19 December 2017 with a double puncture on her head with several trauma and haemorrhages on her back. These instances seem to be the first documented reports of intraspecific killing among free-ranging leopards in Asia.     

<Emphasis Type="Italic">INFLORESCENCE DEFICIENT IN ABSCISSION-like</Emphasis> is an abscission-associated and phytohormone-regulated gene in flower separation of <Emphasis Type="Italic">Lupinus luteus</Emphasis>

Abscission is a natural process that occurs to facilitate shedding of no longer needed organs, but on the other hand, can be triggered by certain environmental conditions, e.g. biotic or abiotic stresses. Regardless of the stimuli, organ shedding takes place specifically at the abscission zone (AZ). A signaling pathway that controls this process in Arabidopsis thaliana from ligand to receptors has been proposed. However, knowledge concerning the influence of plant hormones on these molecular elements still remains enigmatic. Excessive and premature flower abscission in the crop species Lupinus luteus L. is a process of substantial interest to the agricultural industry, as it can affect yield. Our strategy combined molecular studies, comprehensive ultrastructural and histological analysis, as well as exogenous hormone treatment to describe the contribution of the Lupinus IDA-like gene in flower abscission. In the AZ of the naturally abscised flowers, the differentiation of morphologically distinct cells characterized by progressive degradation processes was accompanied by LlIDL mRNA accumulation. A similar effect was observed following early steps of AZ activation and after abscisic acid or ethylene treatments. These phytohormones, previously pointed out as key stimulators of flower separation, altered the temporal expression pattern of LlIDL. Exogenous EPIP peptide synthesized on the basis of LlIDL sequence, significantly increased flower abortion rate, which indicates that this motif governs protein activity. In conclusion, our data provide new evidence for LlIDA involvement in both the early and late events of flower abscission supported by detailed spatiotemporal characterization of AZ cell structure and ultrastructure.