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Vitamin K epoxide reductase (VKOR) generates vitamin K hydroquinone to sustain gamma-carboxylation of many blood coagulation factors. Here, we report the 3.6 A crystal structure of a bacterial homologue of VKOR from Synechococcus sp. The structure shows VKOR in complex with its naturally fused redox partner, a thioredoxin-like domain, and corresponds to an(More)
The SecA ATPase moves polypeptides post-translationally across the plasma membrane of eubacteria, but the mechanism of transport is still unclear. We describe the crystal structure of a novel dimeric form of Bacillus subtilis SecA. Dimerization of SecA occurs at the prominent groove formed by the nucleotide binding domain 2 (nbd2) and the preprotein(More)
Proteins are translocated across membranes through a channel that is formed by the prokaryotic SecY or eukaryotic Sec61 complex. The crystal structure of the SecY channel from M. jannaschii revealed a plug domain that appears to seal the channel in its closed state. However, the role of the plug remains unclear, particularly because plug deletion mutants in(More)
The structure of a synaptic intermediate of the site-specific recombinase gammadelta resolvase covalently linked through Ser10 to two cleaved duplex DNAs has been determined at 3.4 angstrom resolution. This resolvase, activated for recombination by mutations, forms a tetramer whose structure is substantially changed from that of a presynaptic complex(More)
NL63 coronavirus (NL63-CoV), a prevalent human respiratory virus, is the only group I coronavirus known to use angiotensin-converting enzyme 2 (ACE2) as its receptor. Incidentally, ACE2 is also used by group II SARS coronavirus (SARS-CoV). We investigated how different groups of coronaviruses recognize the same receptor, whereas homologous group I(More)
Biosynthesis of ubiquinones requires the intramembrane UbiA enzyme, an archetypal member of a superfamily of prenyltransferases that generates lipophilic aromatic compounds. Mutations in eukaryotic superfamily members have been linked to cardiovascular degeneration and Parkinson's disease. To understand how quinones are produced within membranes, we report(More)
Vitamin K epoxide reductase (VKOR) sustains blood coagulation by reducing vitamin K epoxide to the hydroquinone, an essential cofactor for the gamma-glutamyl carboxylation of many clotting factors. The physiological redox partner of VKOR remains uncertain, but is likely a thioredoxin-like protein. Here, we demonstrate that human VKOR has the same membrane(More)
The structures of two mutants of the site-specific recombinase, gammadelta resolvase, that form activated tetramers have been determined. One, at 3.5-A resolution, forms a synaptic intermediate of resolvase that is covalently linked to two cleaved DNAs, whereas the other is of an unliganded structure determined at 2.1-A resolution. Comparisons of the four(More)
Many secretory proteins are targeted by signal sequences to a protein-conducting channel, formed by prokaryotic SecY or eukaryotic Sec61 complexes, and are translocated across the membrane during their synthesis. Crystal structures of the inactive channel show that the SecY subunit of the heterotrimeric complex consists of two halves that form an(More)
Realgar is a traditional Chinese medicine, which has been used for thousands of years and are claimed to have therapeutic effects. The toxicity from realgar or realgar-containing traditional medicines has raised public concern. However, the neurotoxicity induced by realgar is less reported. Amino acid neurotransmitters are closely linked to the(More)