Lon-mediated proteolysis of the Escherichia coli UmuD mutagenesis protein: in vitro degradation and identification of residues required for proteolysis

Article Abstract:

Most SOS mutagenesis in Escherichia coli is dependent on the UmuC and UmuD proteins which have very precisely regulated activity. It has been recently found that highly purified UmuD protein is specifically degraded in vitro by Lon in a way that is ATP-dependent. To identify regions of UmuD required for Lon-mediated proteolysis, alanine-stretch mutagenesis has been carried out on UmuD. Stability of the mutant protein was checked in vivo. The site or sites within UmuD responsible for Lon-mediated proteolysis were found. The main signal is between residues 15 and 18 (FPLF) of the amino terminus of UmuD. An auxiliary site is between residues 16 and 19 (FPSP). The amino terminus of UmuD is apparently adequate for Lon recognition and later degradation of the protein.

Observations, Escherichia coli, Proteases, Cellular signal transduction, Chromosome replication, Proteolysis, Mutagenesis

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The Saccharomyces telomere-binding protein Cdc13p interacts with both the catalytic subunit of DNA polymerase alpha and the telomerase-associated Est1 protein

Article Abstract:

The Saccharomyces telomere-binding protein Cdc13p interacts with both the catalytic subunit of DNA polymerase alpha and the telomerase-associated Est1 protein. - Qi - Cdc13p, a Saccharomyces telomere-binding protein, has been found to interact with the telomerase-associated Est1 protein and the catalytic subunit of DNA polymerase alpha, based on two hybrid analyses. It has been proposed that Cdc13p's interaction with Est1p promotes TG(sub.1-3) strand-lengthening by telomerase. It is also thought that its interaction with Pol1p promotes C(sub.1-3)A strand-resynthesis by DNA polymerase alpha.

Statistical Data Included, Telomeres, Carrier proteins, Transport proteins, Cytochemistry

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pol(iota), a remarkably error-prone human DNA polymerase

Article Abstract:

Research has shown pol(iota) to be a very highly error-prone human eukaryotic DNA polymerase. In vitro, it shows an atypical misincorporation spectrum. Experiments showed the second of two Rad30 homologs in humans encodes a novel DNA polymerase called pol(iota). The RAD30 gene in Saccharomyces cerevisiae encodes DNA polymerase eta.

Cytogenetics, Xeroderma pigmentosum

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