The presence of multiple copies of the major replicative DNA polymerase (DnaE) in some organisms, including important pathogens and symbionts, has remained an unresolved enigma. We postulated that one copy might participate in error-prone DNA repair synthesis. We found that UV irradiation of Mycobacterium tuberculosis results in increased mutation frequency in the surviving fraction. We identif...

Multiphoton ionization of thymine and uracil clusters generated by a supersonic molecular beam gave rise to a remarkable alternation of mass spectral intensities between even- and odd-numbered clusters. Such alternation was observed in clusters of up to 30 molecules. Excitation to the two lowest electronically excited states seemed to be a strong prerequisite. In view of the well known photodim...

Astaxanthin is a xanthophill pigment with commercial application in the aquaculture, pharmaceutical, food and cosmetic industries. The red yeast Xanthophyllomyces dendrorhous is one of the most promising microorganisms for its industrial production. However, astaxanthin content in wild yeast strains is low. Pigment production by X. dendrorhous can be improved by mutagenesis. The aim of the stud...

Nucleotide excision repair (NER) and DNA repair by photolyase in the presence of light (photoreactivation) are the major pathways to remove UV-induced DNA lesions from the genome, thereby preventing mutagenesis and cell death. Photoreactivation was found in many prokaryotic and eukaryotic organisms, but not in mammals, while NER seems to be universally distributed. Since packaging of eukaryotic...

The role of Acinetobacter baumannii ATCC 17978 UmuDC homologs A1S_0636-A1S_0637, A1S_1174-A1S_1173, and A1S_1389 (UmuDAb) in antibiotic resistance acquired through UV-induced mutagenesis was evaluated. Neither the growth rate nor the UV-related survival of any of the three mutants was significantly different from that of the wild-type parental strain. However, all mutants, and especially the um...

The DDB2 gene, which is mutated in xeroderma pigmentosum group E, enhances global genomic repair of cyclobutane pyrimidine dimers and suppresses UV-induced mutagenesis. Because DDB2 transcription increases after DNA damage in a p53-dependent manner, we searched for and found a region in the human DDB2 gene that binds and responds transcriptionally to p53. The corresponding region in the mouse D...

The RAD18 gene of Saccharomyces cerevisiae is required for postreplication repair of UV damaged DNA. We have isolated the RAD18 gene, determined its nucleotide sequence and examined if deletion mutations of this gene show different or more pronounced phenotypic effects than the previously described point mutations. The RAD18 gene open reading frame encodes a protein of 487 amino acids, with a c...

Rhodotorula yeasts were isolated from various local sources in Damascus, Syria, during 2012 and 2013. Fifty isolates (23 from leaves trees, 13 from different soils, 6 from different meats, 6 from dairy products, 1 pickle and 1 traditional sweet) were identified using API 20C AUX system. Isolated yeasts were classified into three Rhodotorula species: R. mucilaginosa, R. glutinis and R. minuta re...

Trichoderma is an opportunistic, avirulent plant symbiont. Chitin is the main structural component of fungi, enzyme responsible to metabolize the chitin and various techniques to enhance the chitinolytic enzyme production at the genetic level are receiving great attention to develop the efficient biocontrol agent. UV mutagenesis was found to be one of the novel strategy for developing Trichoder...

We investigated the effect of the BCL2 overexpression on nucleotide excision repair (NER) and DNA replication in UV-irradiated HL60 cells. Forty-eight h after 10 J/m2 irradiation, only 4% of the cyclobutane pyrimidine dimers were removed in the BCL2-overexpressing cells, in contrast to 38% removal in control cells. However, the repair of 6-4 pyrimidine pyrimidone photoproducts was not affected ...