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.
- Mandal, S., Ji, W., & McKnight, T. D. (2020). Candidate Gene Networks for Acylsugar Metabolism and Plant Defense in Wild Tomato Solanum pennellii([OPEN]). The Plant Cell. 32(1), 81-99.
- Misra, A., McKnight, T. D., & Mandadi, K. K. (2018). Bromodomain proteins GTE9 and GTE11 are essential for specific BT2-mediated sugar and ABA responses in Arabidopsis thaliana. PLANT MOLECULAR BIOLOGY. 96(4-5), 393-402.
- GÃ³ngora-Castillo, E., Childs, K. L., Fedewa, G., Hamilton, J. P., Liscombe, D. K., Magallanes-Lundback, M., ... Buell, C. R. (2012). Development of Transcriptomic Resources for Interrogating the Biosynthesis of Monoterpene Indole Alkaloids in Medicinal Plant Species. PLoS ONE. 7(12), e52506-e52506.
- Robinson, W. D., Park, J., Tran, H. T., Del Vecchio, H. A., Ying, S., Zins, J. L., ... Plaxton, W. C. (2012). The secreted purple acid phosphatase isozymes AtPAP12 and AtPAP26 play a pivotal role in extracellular phosphate-scavenging by Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY. 63(18), 6531-6542.
- Shakirov, E. V., McKnight, T. D., & Shippen, D. E. (2009). POT1-independent single-strand telomeric DNA binding activities in Brassicaceae. Plant J. 58(6), 1004-1015.
- Patel, K., Lockless, S., Thomas, B., & McKnight, T. D. (1999). Secreted purple acid phosphatase from Arabidopsis thaliana. 19, 373-375.
- Patel, K., Lockless, S., Thomas, B., & McKnight, T. D. (1996). A secreted purple acid phosphatase from Arabidopsis.. Plant Physiol. 111(2), 271-271.
- Hua, L., Henning, D., Patel, K., Brown, L., Teoh, T., & McKnight, T. D. (1996). Molecular biology of camptothecin production. Plant Physiol. 111(2), 618-618.
- PATEL, K., LU, H., HENNING, D., & MCKNIGHT, T. D. (1995). MOLECULAR-BIOLOGY OF CAMPTOTHECIN BIOSYNTHESIS. Plant Physiol. 108(2), 138-138.
- MCKNIGHT, T. D., & HENNING, D. D. (1994). CAMPTOTHECIN, AN ANTI-CANCER ALKALOID FROM CAMPTOTHECA-ACUMINATA (NYSSACEAE). CONSERVATION OF PLANT GENES II: UTILIZATION OF ANCIENT AND MODERN DNA. 48, 149-158.
- Boltz, Kara A. (2013-12). Telomere Regulation in Arabidopsis thaliana by the CST Capping Complex and DNA Damage Response Proteins. (Doctoral Dissertation)
- Misra, Anjali (2011-12). The Bromodomain Proteins GTE9 and GTE11 Associate with BT2-based E3 Ligase Complex and Mediate Responses to Multiple Signals in Arabidopsis thaliana.. (Doctoral Dissertation)
- Mandadi, Kranthi Kiran (2010-08). BT2, a BTB Scaffold Protein, Mediates Responses to Multiple Biotic and Abiotic Signals in Arabidopsis. (Doctoral Dissertation)
- Thomas, Beth Elene Armstrong (2006-12). Regulation of phosphate starvation response in Arabidopsis. (Master's Thesis)
- Patel, Ketan (2006-12). Purple acid phosphatase 12: a tool to study the phosphate starvation response in Arabidopsis thaliana. (Doctoral Dissertation)