TELOMERASE ACTIVATOR1 induces telomerase activity and potentiates responses to auxin in Arabidopsis.
Telomerase activity is highly regulated, abundant in rapidly dividing cells and reproductive organs, but undetectable in most other differentiated tissues. Little is known about mechanisms that regulate telomerase. Here, we used a biochemical assay to screen activation-tagged lines of Arabidopsis thaliana for mutants that ectopically express this enzyme in their leaves. In one such mutant, a previously uncharacterized zinc-finger protein we designate TELOMERASE ACTIVATOR1 (TAC1) is overexpressed and induces telomerase in fully differentiated leaves without stimulating progression through the cell cycle. Reducing endogenous concentrations of auxin in the mutant blocks the ability of TAC1 to induce telomerase. This result, along with other phenotypes of the mutant, such as the ability of cells to grow in culture without exogenous auxin and increased sensitivity of primary root growth to exogenous auxin, indicates that TAC1 not only is part of the previously reported link between auxin and telomerase expression but also potentiates other classic responses to this phytohormone.
Department of Biology, Texas A&M University, College Station, Texas 77843-3258, USA.
Shuxin
S
Ren
J Spencer
JS
Johnston
Dorothy E
DE
Shippen
Thomas D
TD
McKnight
D000595:Amino Acid Sequence / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D020536:Enzyme Activators / Q000302:isolation & purification / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D018517:Plant Roots / Q000201:enzymology / Q000254:growth & development; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D019098:Telomerase / Q000378:metabolism*; D016335:Zinc Fingers / Q000235:genetics
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D018076:DNA, Complementary; D020536:Enzyme Activators; D007210:Indoleacetic Acids; C497726:TAC1 protein, Arabidopsis; D019098:Telomerase