Learn More
Members of the casein kinase-1 family of protein kinases play an essential role in cell regulation and disease pathogenesis. Unlike most protein kinases, they appear to function as constitutively active enzymes. As a result, selective pharmacological inhibitors can play an important role in dissection of casein kinase-1-dependent processes. To address this(More)
We have determined X-ray crystal structures with up to 1.5 Å resolution of the catalytic domain of death-associated protein kinase (DAPK), the first described member of a novel family of pro-apoptotic and tumor-suppressive serine/threonine kinases. The geometry of the active site was studied in the apo form, in a complex with nonhydrolyzable AMPPnP and in a(More)
Many viruses regulate translation of polycistronic mRNA using a -1 ribosomal frameshift induced by an RNA pseudoknot. A pseudoknot has two stems that form a quasi-continuous helix and two connecting loops. A 1.6 Å crystal structure of the beet western yellow virus (BWYV) pseudoknot reveals rotation and a bend at the junction of the two stems. A loop base is(More)
A biochemical oscillator can be reconstituted in vitro with three purified proteins, that displays the salient properties of circadian (daily) rhythms, including self-sustained 24-h periodicity that is temperature compensated. We analyze the biochemical basis of this oscillator by quantifying the time-dependent interactions of the three proteins (KaiA,(More)
Circadian (daily) biological clocks express characteristics that are difficult to explain by known biochemical mechanisms, and will ultimately require characterizing the structures, functions, and interactions of their molecular components. KaiC is an essential circadian protein in cyanobacteria that forms the core of the KaiABC clock protein complex. We(More)
In cyanobacteria, KaiC is an essential hexameric clock protein that forms the core of a circadian protein complex. KaiC can be phosphorylated, and the ratio of phospho-KaiC to non-phospho-KaiC is correlated with circadian period. Structural analyses of KaiC crystals identify three potential phosphorylation sites within a 10-A radius of the ATP binding(More)
The cyanobacterial circadian clock can be reconstituted in vitro by mixing recombinant KaiA, KaiB and KaiC proteins with ATP, producing KaiC phosphorylation and dephosphorylation cycles that have a regular rhythm with a ca. 24-h period and are temperature-compensated. KaiA and KaiB are modulators of KaiC phosphorylation, whereby KaiB antagonizes KaiA's(More)
In contrast to replicative DNA polymerases, Sulfolobus solfataricus Dpo4 showed a limited decrease in catalytic efficiency (k(cat)/Km) for insertion of dCTP opposite a series of N2-alkylguanine templates of increasing size from (methyl (Me) to (9-anthracenyl)-Me (Anth)). Fidelity was maintained with increasing size up to (2-naphthyl)-Me (Naph). The(More)
The crystal structure of the RNA duplex [r(CCCCGGGG)]2 has been refined to 1.46 A resolution with room temperature synchrotron diffraction data. This represents the highest resolution reported to date for an all-RNA oligonucleotide and is well beyond the best resolution ever achieved with an A-form DNA duplex. The analysis of the ordered hydration around(More)
The circadian clock of the cyanobacterium Synechococcus elongatus can be reconstituted in vitro by the KaiA, KaiB and KaiC proteins in the presence of ATP. The principal clock component, KaiC, undergoes regular cycles between hyper- and hypo-phosphorylated states with a period of ca. 24 h that is temperature compensated. KaiA enhances KaiC phosphorylation(More)