- B.S., 1975, University of Georgia, Microbiology.
- Ph.D., 1983, University of Georgia, Molecular and population genetics.
- Postdoctoral research: Atlantic Richfield Plant Cell Research Institute
Joined the department in 1985.
Associations: Faculty of Genetics, Faculty of Plant Physiology, Graduate Program in Molecular Cell Biology.
College Station, TX 77843-3258
Biological Sciences Building East
Biological Sciences Building East
|Plant Molecular and Cell Biology
My lab is currently investigating mechanisms that regulate telomerase activity in plants. We previously showed that the pattern of telomerase expression in plants is remarkably similar to the pattern seen in humans, despite fundamental differences in development between plants and animals. Telomerase is abundantly expressed in reproductive organs but is undetectable in most vegetative organs (Fitzgerald et al., 1996). Additionally, telomerase can be induced in leaves and other vegetative organs by exposure to exogenous auxin.
To isolate genes that regulate telomerase, we screened a large population of activation tagged lines of Arabidopsis thaliana, and found that several lines that ectopically express telomerase in leaves. The first line we characterized over-expressed a gene encoding a small zinc finger transcription factor we designated TELOMERASE ACTIVATOR 1 (Ren et al., 2004). This factor does not bind to the promoter for TERT, which encodes the catalytically active subunit of telomerase. Instead, it binds to and activates transcription of BT2, a gene encoding a component of a ubiquitin ligase (Ren et al., 2007). Our working model is that the BT2 ubiquitin ligase marks a telomerase repressor for destruction, thereby allowing expression of telomerase. Efforts in the lab are currently focused on identifying the presumed telomerase repressor protein and other proteins that interact with BT2.
- Góngora-Castillo E, Childs KL, Fedewa G, Hamilton JP, Liscombe DK, Magallanes-Lundback M, Mandadi KK, Nims E, Runguphan W, Vaillancourt B, Varbanova-Herde M, Dellapenna D, McKnight TD, O'Connor S & Buell CR (2012) Development of transcriptomic resources for interrogating the biosynthesis of monoterpene indole alkaloids in medicinal plant species. PLoS One 7:e52506 Full text
- Robinson WD, Park J, Tran HT, Del Vecchio HA, Ying S, Zins JL, Patel K, McKnight TD & Plaxton WC (2012) The secreted purple acid phosphatase isozymes AtPAP12 and AtPAP26 play a pivotal role in extracellular phosphate-scavenging by Arabidopsis thaliana. J Exp Bot 63:6531-42 Full text
- Mandadi KK, Misra A, Ren S & McKnight TD (2009) BT2, a BTB protein, mediates multiple responses to nutrients, stresses, and hormones in Arabidopsis. Plant Physiol 150:1930-9 Full text
- Shakirov EV, McKnight TD & Shippen DE (2009) POT1-independent single-strand telomeric DNA binding activities in Brassicaceae. Plant J 58:1004-15 Full text
- Ren S, Mandadi KK, Boedeker AL, Rathore KS & McKnight TD (2007) Regulation of telomerase in Arabidopsis by BT2, an apparent target of TELOMERASE ACTIVATOR1. Plant Cell 19:23-31 Full text
- Lu H, Gorman E & McKnight TD (2005) Molecular characterization of two anthranilate synthase alpha subunit genes in Camptotheca acuminata. Planta 221:352-60 Full text
- Ren S, Johnston JS, Shippen DE & McKnight TD (2004) TELOMERASE ACTIVATOR1 induces telomerase activity and potentiates responses to auxin in Arabidopsis. Plant Cell 16:2910-22 Full text
- McKnight TD & Shippen DE (2004) Plant telomere biology. Plant Cell 16:794-803 Full text
- McKnight TD, Riha K & Shippen DE (2002) Telomeres, telomerase, and stability of the plant genome. Plant Mol Biol 48:331-7 Full text
- Fitzgerald MS, Shakirov EV, Hood EE, McKnight TD & Shippen DE (2001) Different modes of de novo telomere formation by plant telomerases. Plant J 26:77-87 Full text