Genetic and biochemical analyses of Pfh1 DNA helicase function in fission yeast.

The Schizosaccharomyces pombe pfh1+ gene (PIF1 homolog) encodes an essential enzyme that has both DNA helicase and ATPase activities and is implicated in lagging strand DNA processing. Mutations in the pfh1+ gene suppress a temperature-sensitive allele of cdc24+, which encodes a protein that functions with Schizosaccharomyces pombe Dna2 in Okazaki fragment processing. In this study, we describe the enzymatic properties of the Pfh1 helicase and the genetic interactions between pfh1 and cdc24, dna2, cdc27 or pol 3, all of which are involved in the Okazaki fragment metabolism.

Wideband enhancement of television images for people with visual impairments.

Wideband enhancement was implemented by detecting visually relevant edge and bar features in an image to produce a bipolar contour map. The addition of these contours to the original image resulted in increased local contrast of these features and an increase in the spatial bandwidth of the image. Testing with static television images revealed that visually impaired patients (n = 35) could distinguish the enhanced images and preferred them over the original images (and degraded images).

SCFhFBH1 can act as helicase and E3 ubiquitin ligase.

In our previous study, we found that a human F-box DNA helicase, named hFBH1, interacted with SKP1 to form an SCF (SKP1-Cul1-F-box protein) complex together with CUL1 and ROC1 in an F-box-dependent manner. The complex immunoprecipitated from crude cell extracts catalyzed polyubiquitin formation in the presence of the ubiquitin-activating and ubiquitin-conjugating enzymes, E1 and E2, respectively. In this report, we characterized the enzymatic properties of the recombinant SCF(hFBH1) complex purified from insect cells expressing hFBH1, SKP1, CUL1 and ROC1.

Coupling of DNA helicase and endonuclease activities of yeast Dna2 facilitates Okazaki fragment processing.

Saccharomyces cerevisiae Dna2 possesses both helicase and endonuclease activities. Its endonuclease activity is essential and well suited to remove RNA-DNA primers of Okazaki fragments. In contrast, its helicase activity, although required for optimal growth, is not essential when the rate of cell growth is reduced.

The novel human DNA helicase hFBH1 is an F-box protein.

We have identified a novel DNA helicase in humans that belongs to members of the superfamily I helicase and found that it contains a well conserved F-box motif at its N terminus. We have named the enzyme hFBH1 (human F-box DNA helicase 1). Recombinant hFBH1, containing glutathione S-transferase at the N terminus, was expressed in Sf9 cells and purified.