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The REC1 gene of Ustilago maydis involved in the cellular response to DNA damage encodes an exonuclease.

TitleThe REC1 gene of Ustilago maydis involved in the cellular response to DNA damage encodes an exonuclease.
Publication TypeJournal Article
Year of Publication1994
AuthorsThelen MP, Onel K, Holloman WK
JournalJ Biol Chem
Volume269
Issue1
Pagination747-54
Date Published1994 Jan 7
ISSN0021-9258
KeywordsAmino Acid Sequence, Base Sequence, Chromatography, Gel, DNA Damage, DNA Repair, DNA, Fungal, Electrophoresis, Polyacrylamide Gel, Exodeoxyribonuclease V, Exodeoxyribonucleases, Fungal Proteins, Genes, Fungal, Molecular Sequence Data, Recombination, Genetic, Sequence Homology, Amino Acid, Ustilago
Abstract

Mutation in the REC1 gene of Ustilago maydis is known to lead to a complex phenotype with alterations in DNA repair, recombination, mutagenesis, meiosis, and cell division. The predicted product of the REC1 gene is a polypeptide of 522 amino acid residues with a molecular mass of 56,866 daltons, with no overall sequence homology to any other known protein. The open reading frame of the REC1 gene placed by itself in a U. maydis expression vector was found to be sufficient to complement the rec1 mutant. Overexpression of REC1 in Escherichia coli gave rise to the anticipated 57-kDa product together with a 3'-->5' exonuclease activity. This activity was only present in cells overexpressing REC1 and its characteristics were distinguishable from the major bacterial nucleases, but it had certain enzymatic features in common with epsilon, the proofreading exonuclease subunit of E. coli DNA polymerase III holoenzyme. To facilitate isolation of the protein product from bacteria, the REC1 gene was overexpressed from a vector that fused a hexa-histidine-leader sequence onto the amino terminus, enabling the isolation of the HisREC1 product on an immobilized metal ion affinity column. The His-REC1 protein co-eluted with the novel exonuclease activity. Alignment of the amino acid sequence of the REC1 gene product with the conserved proofreading exonuclease motifs of DNA polymerases indicated significant homology.

Alternate JournalJ. Biol. Chem.
PubMed ID8276878
Grant ListGM42482 / GM / NIGMS NIH HHS / United States

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