• 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 Molecular and Environmental Plant Sciences, Graduate Program in Molecular Cell Biology.

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.

  1. Góngora-Castillo, E, Childs, KL, Fedewa, G, Hamilton, JP, Liscombe, DK, Magallanes-Lundback, M et al.. Development of transcriptomic resources for interrogating the biosynthesis of monoterpene indole alkaloids in medicinal plant species. PLoS ONE. 2012;7 (12):e52506. Epub 2012/12/26. doi: 10.1371/journal.pone.0052506. PubMed PMID:23300689 PubMed Central PMC3530497.
  2. Robinson, WD, Park, J, Tran, HT, Del Vecchio, HA, Ying, S, Zins, JL et al.. The secreted purple acid phosphatase isozymes AtPAP12 and AtPAP26 play a pivotal role in extracellular phosphate-scavenging by Arabidopsis thaliana. J. Exp. Bot. 2012;63 (18):6531-42. doi: 10.1093/jxb/ers309. PubMed PMID:23125358 PubMed Central PMC3504502.
  3. Mandadi, KK, Misra, A, Ren, S, McKnight, TD. BT2, a BTB protein, mediates multiple responses to nutrients, stresses, and hormones in Arabidopsis. Plant Physiol. 2009;150 (4):1930-9. doi: 10.1104/pp.109.139220. PubMed PMID:19525324 PubMed Central PMC2719139.
  4. Shakirov, EV, McKnight, TD, Shippen, DE. POT1-independent single-strand telomeric DNA binding activities in Brassicaceae. Plant J. 2009;58 (6):1004-15. doi: 10.1111/j.1365-313X.2009.03837.x. PubMed PMID:19228335 .
  5. Ren, S, Mandadi, KK, Boedeker, AL, Rathore, KS, McKnight, TD. Regulation of telomerase in Arabidopsis by BT2, an apparent target of TELOMERASE ACTIVATOR1. Plant Cell. 2007;19 (1):23-31. doi: 10.1105/tpc.106.044321. PubMed PMID:17220202 PubMed Central PMC1820974.
  6. Lu, H, Gorman, E, McKnight, TD. Molecular characterization of two anthranilate synthase alpha subunit genes in Camptotheca acuminata. Planta. 2005;221 (3):352-60. doi: 10.1007/s00425-004-1450-z. PubMed PMID:15645305 .
  7. Ren, S, Johnston, JS, Shippen, DE, McKnight, TD. TELOMERASE ACTIVATOR1 induces telomerase activity and potentiates responses to auxin in Arabidopsis. Plant Cell. 2004;16 (11):2910-22. doi: 10.1105/tpc.104.025072. PubMed PMID:15486103 PubMed Central PMC527188.
  8. McKnight, TD, Shippen, DE. Plant telomere biology. Plant Cell. 2004;16 (4):794-803. doi: 10.1105/tpc.160470. PubMed PMID:15064365 PubMed Central PMC526047.
  9. McKnight, TD, Riha, K, Shippen, DE. Telomeres, telomerase, and stability of the plant genome. Plant Mol. Biol. 2002;48 (4):331-7. . PubMed PMID:11905960 .
  10. Fitzgerald, MS, Shakirov, EV, Hood, EE, McKnight, TD, Shippen, DE. Different modes of de novo telomere formation by plant telomerases. Plant J. 2001;26 (1):77-87. . PubMed PMID:11359612 .
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Tom McKnight

Tom McKnight
Professor and
Department Head

3258 TAMU
College Station, TX 77843-3258

Office:
Biological Sciences Building East
Room 202C
Butler Hall
Room 100B
979-845-3896

Lab:
Biological Sciences Building East
Room 206
979-845-6749

Fax: 979-845-2891
Email: mcknight@bio.tamu.edu

Curriculum Vitae