title: Role of silicon on diatom metabolism. IX. Differential synthesis of DNA polymerases and DNA-binding proteins during silicate starvation and recovery in Cylindrotheca fusiformis.
abstract: During recovery from silicate-starvation, a period of active DNA synthesis, synchronized cells of Cylindrotheca fusiformis incorporated 3 times more L-[U-14C]aspartate than did starved cells. Of the diatoms's four DNA polymerases, A and D are synthesized during silicate recovery, indicating that they are involved in silicate-dependent DNA replication. Polymerase B, and the chloroplast enzyme, polymerase C, are synthesized during silicate-starvation and their levels are unaffected by the addition of silicate. DEAE-Sephadex analysis of the DNA-binding proteins, labeled with [14C]- and [3H]asparate, shows that only three proteins are synthesized in cells recovering from silicate-starvation. Two of these proteins correspond to polymerases A and D, while the function of the third protein is not known. At least 15 other proteins are present in silicate-starved cells and their synthesis is repressed upon the addition of silicate. Models are proposed which describe the modes by which silicate might regulate DNA synthesis in the diatom.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001692:Biological Transport; D002453:Cell Cycle; D002736:Chloroplasts / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism*; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D056890:Eukaryota / Q000378:metabolism*; D012822:Silicon Dioxide / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D012822:Silicon Dioxide; D004259:DNA-Directed DNA Polymerase; D004265:DNA Helicases