Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates

A metal-free route for the synthesis of biarenes has been developed. The approach is based on the photoextrusion of a phosphate moiety occurring upon irradiation of biaryl- and triaryl phosphates. The reaction involves an exciplex as the intermediate and it is especially suitable for the preparation of electron-rich biarenes.

Metal-free synthesis of biarenes via photoextrusion in di(tri)arylphosphates

A metal-free route for the synthesis of biarenes has been developed. This approach is based on the photoextrusion of a phosphate moiety occurring upon irradiation of biaryl- and triarylphosphates. The reaction involved an exciplex as the intermediate and it is especially suitable for the preparation of electron-rich biarenes.

Short and simple sequences favored the emergence of N-helix phospho-ligand binding sites in the first enzymes

The ubiquity of phospho-ligands suggests that phosphate binding emerged at the earliest stage of protein evolution. To evaluate this hypothesis and unravel its details, we identified all phosphate-binding protein lineages in the Evolutionary Classification of Protein Domains database. We found at least 250 independent evolutionary lineages that bind small molecule cofactors and metabolites with phosphate moieties. For many lineages, phosphate binding emerged later as a niche functionality, but for the oldest protein lineages, phosphate binding was the founding function. Across some 4 billion y of protein evolution, side-chain binding, in which the phosphate moiety does not interact with the backbone at all, emerged most frequently. However, in the oldest lineages, and most characteristically in αβα sandwich enzyme domains, N-helix binding sites dominate, where the phosphate moiety sits atop the N terminus of an α-helix. This discrepancy is explained by the observation that N-helix binding is uniquely realized by short, contiguous sequences with reduced amino acid diversity, foremost Gly, Ser, and Thr. The latter two amino acids preferentially interact with both the backbone amide and the side-chain hydroxyl (bidentate interaction) to promote binding by short sequences. We conclude that the first αβα sandwich domains emerged from shorter and simpler polypeptides that bound phospho-ligands via N-helix sites.

Ran pathway-independent regulation of mitotic Golgi disassembly by Importin-α

To facilitate proper mitotic cell partitioning, the Golgi disassembles by suppressing vesicle fusion. However, the underlying mechanism has not been characterized previously. Here, we report a Ran pathway-independent attenuation mechanism that allows Importin-α (a nuclear transport factor) to suppress the vesicle fusion mediated by p115 (a vesicular tethering factor) and is required for mitotic Golgi disassembly. We demonstrate that Importin-α directly competes with p115 for interaction with the Golgi protein GM130. This interaction, promoted by a phosphate moiety on GM130, is independent of Importin-β and Ran. A GM130 K34A mutant, in which the Importin-α-GM130 interaction is specifically disrupted, exhibited abundant Golgi puncta during metaphase. Importantly, a mutant showing enhanced p115-GM130 interaction presented proliferative defects and G2/M arrest, demonstrating that Importin-α-GM130 binding modulates the Golgi disassembly that governs mitotic progression. Our findings illuminate that the Ran and kinase-phosphatase pathways regulate multiple aspects of mitosis coordinated by Importin-α (e.g. spindle assembly, Golgi disassembly).

Truncated vitamin B12 derivative with the phosphate group retained

Cobyric acid and cobinamide are valuable building blocks for the synthesis of artificial cobalamins modified at the nucleotide loop. However, truncated vitamin B[Formula: see text] derivatives are devoid of the phosphate group. We have found that 2-iodoxy benzoic acid-mediated phosphorolysis leads to the cleavage of only one of the phosphodiester bond giving a vitamin B[Formula: see text] analogue with the phosphate moiety preserved. Subsequent alkylation with an organic halide establishes its role as a precursor for the synthesis of vitamin B[Formula: see text] mimics modified at the nucleotide loop.

Structures of the antibody 64M-5 Fab and its complex with dT(6–4)T indicate induced-fit and high-affinity mechanisms

DNA photoproducts with (6–4) pyrimidine–pyrimidone adducts produced by ultraviolet light are mutagenic and carcinogenic. The crystal structures of the anti-(6–4) photoproduct antibody 64M-5 Fab and of its complex with dT(6–4)T were determined at 2.5 and 2.0 Å resolution, respectively. A comparison between the dT(6–4)T-liganded and unliganded structures indicates that the side chain of His93L is greatly rotated and shifted on binding to dT(6–4)T, leading to the formation of an electrostatic interaction with the phosphate moiety of dT(6–4)T, which shows a remarkable induced fit. Based on a comparison of the dT(6–4)T-liganded structures of the 64M-5 and 64M-2 Fabs, the electrostatic interaction between the side chain of His93L in 64M-5 and the phosphate moiety of dT(6–4)T is lost for Leu93L in 64M-2, while Arg90L in 64M-5 instead of Gln90L in 64M-2 stabilizes the conformation of complementarity-determining region (CDR) L3. These differences contribute to the higher affinity of 64M-5 for dT(6–4)T compared with that of 64M-2.