SARS coronavirus encodes non-structural protein 13 (nsP13), a nucleic acid helicase/NTPase belonging to superfamily 1 helicase, which efficiently unwinds both partial-duplex RNA and DNA. In this study, unwinding of DNA substrates that had different duplex lengths and 5'-overhangs was examined under single-turnover reaction conditions in the presence of excess enzyme. The amount of DNA unwound d...

Abstract Although additive manufacturing (AM) allows for a large design freedom, there are some limitations that have to be taken into consideration. One of the most restricting rules is minimum allowable overhang angle. To make topology optimization suitable AM, several algorithms been published enforce In this work, layer-by-layer filter proposed by Langelaar ( Struct Multidiscip Optim 55(3):...

Periodontal structures are vital tissues that could be affected by the surrounding environment. Dental materials and/or restorations may trigger negative response such as gingival inflammation and bone loss from periodontal tissues. The objective of this study was to report the prevalence of overhang interproximal amalgam restorations by undergraduate students at College of Dentistry, King Saud...

The debt overhang problem is shown to arise in the context of an entrepreneurial project that requires a sequence of investments financed by an outside lender. The entrepreneur, not internalizing losses accruing to the lender which financed the initial investments, may inefficiently cancel the project and instead pursue an outside opportunity. It is shown that loan commitments (contracts that a...

Bacteria acquire memory of viral invaders by incorporating invasive DNA sequence elements into the host CRISPR locus, generating a new spacer within the CRISPR array. We report on the structures of Cas1-Cas2-dual-forked DNA complexes in an effort toward understanding how the protospacer is sampled prior to insertion into the CRISPR locus. Our study reveals a protospacer DNA comprising a 23-bp d...

RNase R is a conserved exoribonuclease in the RNase II family that primarily participates in RNA decay in all kingdoms of life. RNase R degrades duplex RNA with a 3' overhang, suggesting that it has RNA unwinding activity in addition to its 3'-to-5' exoribonuclease activity. However, how RNase R coordinates RNA binding with unwinding to degrade RNA remains elusive. Here, we report the crystal s...

Branch capture reactions (BCR) contain three DNA species: (i) a recipient restriction fragment terminating in an overhang, (ii) a displacer strand containing two adjacent sequences, with one complementary to the overhang and to contiguous nucleotides within the recipient duplex and (iii) a linker which is complementary to the second displacer sequence. Branched complexes containing all three sp...

The nonenzymatic replication of primordial RNA is thought to have been a critical step in the origin of life. However, despite decades of effort, the poor rate and fidelity of model template copying reactions have thus far prevented an experimental demonstration of nonenzymatic RNA replication. The overall rate and fidelity of template copying depend, in part, on the affinity of free ribonucleo...

Populations of the Western Scrub-Jay (Aphelocoma californica) have bills specialized for feeding in their respective habitats. Populations in oak habitat have hooked bills, whereas those in pinyon habitat have pointed bills with a reduced maxillary overhang. Work on other bird species shows that the bill overhang is essential for efficient preening to control ectoparasites. Given the importance...

Eukaryotic telomeres have a 12-16 nucleotide long deoxyguanosine (dG) rich single-stranded overhang at their molecular termini. Some of the unique features of telomeres are probably attributable to a specialized structure formed by this overhang. In the ciliated protozoan Tetrahymena thermophila, the dG-rich overhang is comprised of approximately two repeats of the sequence d(TTGGGG). Previous ...