The diversity of cyanobacteria along the Alaskan North Slope was investigated. We isolated and cultivated 57 strains of cyanobacteria and sequenced a section of their rRNA operon containing a fragment of the 16S rRNA gene. Here, we describe 17 found species belonging mainly to families Coleofasciculaceae, Microcoleaceae, Oculatellaceae, Leptolyngbyaceae and to the order Synechococcales. In pursuing a conservative polyphasic approach, we utilized suggested thresholds in 16S rRNA gene differences in parallel with morphological differences between new and already described taxa for the description of new species and genera. Based on a combination of morphological, molecular and ecological analysis of collected and cultured strains we describe two genera Gibliniella and Shackletoniella as well as six cyanobacterial species; Cephalothrix alaskaensis, Tildeniella alaskaensis, Pseudophormidium americanum, Leptodesmis alaskaensis, Albertania alaskaensis and Nodosilinea alaskaensis. Here, a polyphasic approach was used to identify eight novel and nine established cyanobacterial taxa from a previously non–investigated region that uncovered a high degree of biodiversity in extreme polar environments.

Iripin-5 is the main Ixodes ricinus salivary serpin, which acts as a modulator of host defence mechanisms by impairing neutrophil migration, suppressing nitric oxide production by macrophages and altering complement functions. Iripin-5 influences host immunity and shows high expression in the salivary glands. Here, the crystal structure of Iripin-5 in the most thermodynamically stable state of serpins is described. In the reactive-centre loop, the main substrate-recognition site of Iripin-5 is likely to be represented by Arg342, which implies the targeting of trypsin-like proteases. Furthermore, a computational structural analysis of selected Iripin-5–protease complexes together with interface analysis revealed the most probable residues of Iripin-5 involved in complex formation.

The Sec translocon is a transmembrane assembly highly conserved among all forms of life as the principal route for transport of polypeptides across or into lipid bilayers.In bacteria translocation is driven by allosteric communication between the membrane pore SecYEG and the associated SecA ATPase. Using time-resolved single molecule fluorescence we reveal that slow conformational changes associated with SecA ATPase (~ 6 s -1 ) modulate fast opening and closure of the SecY pore (~ 175 s -1 ). Such mismatch of timescales is not compatible with direct coupling between SecAand SecYEG and the power stroke mechanism. A dynamic allosteric model in which SecA ATPase cycle controls energy landscape for SecY pore opening is proposed and consistent with the Brownian-ratchet mechanism. Analysis of structures and molecular dynamics trajectories identified key molecular interactions involved in the mechanism. This dynamic allostery may be common among motor ATPases that drive conformational changes in molecular machines.A fascinating class of biological molecular machines are those operating upon biopolymer substrates and converting chemical energy derived from ATP binding and hydrolysis into cycles of conformational changes and mechanical work (e.g. helicases, translocases,