The reduction of the bulky amido-germanium(II) chloride complex, LGeCl (L = N(SiMe(3))(Ar*); Ar* = C(6)H(2)Me{C(H)Ph(2)}(2)-4,2,6), with the magnesium(I) dimer, [{((Mes)Nacnac)Mg}(2)] ((Mes)Nacnac = [(MesNCMe)(2)CH](-); Mes = mesityl), afforded LGeGeL, which represents the first example of a digermyne with a Ge-Ge single bond. Computational studies of the compound have highlighted significant electronic differences between it and multiply bonded digermynes. LGeGeL was shown to cleanly activate H(2) in solution or the solid state, at temperatures as low as -10 °C, to give the mixed valence compound, LGeGe(H)(2)L.

With a single exception, all isolates of hepatitis C virus (HCV) require adaptive mutations to replicate efficiently in cell culture. Here, we show that a major class of adaptive mutations regulates the activity of a cellular lipid kinase, phosphatidylinositol 4-kinase IIIα (PI4KA). HCV needs to stimulate PI4KA to create a permissive phosphatidylinositol 4-phosphate-enriched membrane microenvironment in the liver and in primary human hepatocytes (PHHs). In contrast, in Huh7 hepatoma cells, the virus must acquire loss-of-function mutations that prevent PI4KA overactivation. This adaptive mechanism is necessitated by increased PI4KA levels in Huh7 cells compared with PHHs, and is conserved across HCV genotypes. PI4KA-specific inhibitors promote replication of unadapted viral isolates and allow efficient replication of patient-derived virus in cell culture. In summary, this study has uncovered a long-sought mechanism of HCV cell-culture adaptation and demonstrates how a virus can adapt to changes in a cellular environment associated with tumorigenesis.

No abstract

Human noroviruses (huNoV) are the most frequent cause of non-bacterial acute gastroenteritis worldwide, particularly genogroup II genotype 4 (GII.4) variants. The viral nonstructural (NS) proteins encoded by the ORF1 polyprotein induce vesical clusters harboring the viral replication sites. Little is known so far about the ultrastructure of these replication organelles or the contribution of individual NS proteins to their biogenesis. We compared the ultrastructural changes induced by expression of norovirus ORF1 polyproteins with those induced upon infection with murine norovirus (MNV). Characteristic membrane alterations induced by ORF1 expression resembled those found in MNV infected cells, consisting of vesicle accumulations likely built from the endoplasmic reticulum (ER) which included single membrane vesicles (SMVs), double membrane vesicles (DMVs) and multi membrane vesicles (MMVs). In-depth analysis using electron tomography suggested that MMVs originate through the enwrapping of SMVs with tubular structures similar to mechanisms reported for picornaviruses. Expression of GII.4 NS1-2, NS3 and NS4 fused to GFP revealed distinct membrane alterations when analyzed by correlative light and electron microscopy. Expression of NS1-2 induced proliferation of smooth ER membranes forming long tubular structures that were affected by mutations in the active center of the putative NS1-2 hydrolase domain. NS3 was associated with ER membranes around lipid droplets (LDs) and induced the formation of convoluted membranes, which were even more pronounced in case of NS4. Interestingly, NS4 was the only GII.4 protein capable of inducing SMV and DMV formation when expressed individually. Our work provides the first ultrastructural analysis of norovirus GII.4 induced vesicle clusters and suggests that their morphology and biogenesis is most similar to picornaviruses. We further identified NS4 as a key factor in the formation of membrane alterations of huNoV and provide models of the putative membrane topologies of NS1-2, NS3 and NS4 to guide future studies.

Very recently it was shown that the metalloid cluster compound {Ge(9)[Si(SiMe(3))(3)](3)}(-) can be used for subsequent reactions as the shielding of the cluster core is rather incomplete. Here further reactions of with M(+) sources of group 11 metals are described, leading to metalloid cluster compounds of the formula {MGe(18)[Si(SiMe(3))(3)](6)}(-) (M = Ag, Cu). These reactions can be seen as first steps into a supramolecular chemistry with metalloid cluster compounds. Beside this feature, the structural properties as well as the bonding situations in these cluster compounds are discussed.

The preparation of a series of extremely bulky secondary amines, Ar*N(H)SiR(3) (Ar* = C(6)H(2){C(H)Ph(2)}(2)Me-2,6,4; R(3) = Me(3), MePh(2) or Ph(3)) is described. Their deprotonation with either LiBu(n), NaH or KH yields alkali metal amide complexes, several monomeric examples of which, [Li(L){N(SiMe(3))(Ar*)}] (L = OEt(2) or THF), [Na(THF)(3){N(SiMe(3))(Ar*)}] and [K(OEt(2)){N(SiPh(3))(Ar*)], have been crystallographically characterised. Reactions of the lithium amides with germanium, tin or lead dichloride have yielded the first structurally characterised two-coordinate, monomeric amido germanium(II) and tin(II) chloride complexes, [{(SiR(3))(Ar*)N}ECl] (E = Ge or Sn; R = Me or Ph), and a chloride bridged amido-lead(II) dimer, [{[(SiMe(3))(Ar*)N]Pb(μ-Cl)}(2)]. DFT calculations on [{(SiMe(3))(Ar*)N}GeCl] show its HOMO to exhibit Ge lone pair character and its LUMO to encompass its Ge based p-orbital. A series of bulky amido silicon(IV) chloride complexes have also been prepared and several examples, [{(SiR(3))(Ar*)N}SiCl(3)] (R(3) = Me(3), MePh(2)) and [{(SiMe(3))(Ar*)N}SiHCl(2)], were crystallographically characterised. The sterically hindered group 14 complexes reported in this study hold significant potential as precursors for kinetically stabilised low oxidation state and/or low coordination number group 14 complexes.

The reactions of the metalloid cluster {Ge9[Si(SiMe3)3]3}- with Cr(CO)5COE (COE=cyclooctene) and Cr(CO)3(CH3CN)3 lead to the new cluster compounds {Ge9[Si(SiMe3)3]3Cr(CO)5}- and {Ge9[Si(SiMe3)3]3Cr(CO)3}-, whose structural and electronic properties are presented.

Metalloid clusters of Group 14 have been established as a discrete group of cluster compounds [1,2] during the last years. [3,4] The metalloid clusters of the general formula [M n R m ] (n > m; M = Si, Ge, Sn, Pb) contain ligand-bound metal atoms as well as "naked" metal atoms. Since the "naked" metal atoms inside these clusters exhibit an oxidation state of 0, the average oxidation state of the metal atoms within metalloid Group 14 cluster compounds is between 0 and 1. Therefore, these cluster compounds can be seen as intermediates on the way to the elemental state, and structural approaches toward the solid-state phase have been reported recently. [2,5] Another interesting class of Group 14 cluster compounds that has been known for a long time is the Zintl anions.[6] In the case of the Zintl anions, characterization of the anionic species could be accomplished and subsequent reactions could be established during the last few years. Most results were obtained with the Zintl anion [Ge 9 ] 4À , which was linked to a dimer, [7] an oligomer, [8] or a polymer.[ , in which two {Ge 9 } units are connected through a {Ni 3 } bridge.[10] Furthermore, Au-bound Zintl anions such as [Au 3 Ge 18 ] 5À (1) [11] and [Au 3 Ge 45 ] 9À (2) [12] could be synthesized. In the case of metalloid Group 14 cluster compounds no subsequent reaction has been reported, and thus we wondered if such reactions might also be possible. A promising candidate for such reactions seemed to be the metalloid cluster compound [Ge 9 R 3 ] À (3, R = Si(SiMe 3 ) 3 ), [13] in which six naked germanium atoms are readily available for subsequent reactions. First results prove the case for our assumption, and we present herein the first subsequent reaction of a metalloid cluster compound, leading to the cluster compound [AuGe 18 R 6 ] À (4, R = Si(SiMe 3 ) 3 ). For the synthesis of 4, we treated a solution of 3 in THF with [AuCl(PPh 3 )]. The reaction solution changed color from orange to red, and a white precipitate of LiCl was formed. After workup of the reaction mixture, the anionic cluster 4, which crystallizes together with [Li(thf) 6 ] + as counterion, could be isolated in the form of red crystals.As shown in Figure 1, the molecular structure of 4 consists of two {Ge 9 R 3 } units which are connected by a central gold atom. The [Li(thf) 6 ] + salt of 4 crystallizes in the trigonal crystal system in the space group R3 , whereby the gold atom is located at the center of inversion. The central {Ge 18 Au} unit has D 3d symmetry, and since the Si(SiMe 3 ) 3 ligands are twisted by 37.78 against the mirror plane, the symmetry of the whole cluster is reduced to C 3i . The steric demand of the six Si(SiMe 3 ) 3 ligands is so large that the ligands are interlocked, [14] totally shielding the central gold atom against the exterior (Figure 2).The gold atom is bound trigonal-antiprismatic to six germanium atoms and owing to the high coordination