@article{alejos-gonzalez_qu_zhou_saravitz_shurtleff_xie_2011, title={Characterization of development and artemisinin biosynthesis in self-pollinated Artemisia annua plants}, volume={234}, ISSN={["1432-2048"]}, DOI={10.1007/s00425-011-1430-z}, abstractNote={Artemisia annua L. is the only natural resource that produces artemisinin (Qinghaosu), an endoperoxide sesquiterpene lactone used in the artemisinin-combination therapy of malaria. The cross-hybridization properties of A. annua do not favor studying artemisinin biosynthesis. To overcome this problem, in this study, we report on selection of self-pollinated A. annua plants and characterize their development and artemisinin biosynthesis. Self-pollinated F2 plants selected were grown under optimized growth conditions, consisting of long day (16 h of light) and short day (9 h of light) exposures in a phytotron. The life cycles of these plants were approximately 3 months long, and final heights of 30-35 cm were achieved. The leaves on the main stems exhibited obvious morphological changes, from indented single leaves to odd, pinnately compound leaves. Leaves and flowers formed glandular and T-shaped trichomes on their surfaces. The glandular trichome densities increased from the bottom to the top leaves. High performance liquid chromatography-mass spectrometry-based metabolic profiling analyses showed that leaves, flowers, and young seedlings of F2 plants produced artemisinin. In leaves, the levels of artemisinin increased from the bottom to the top of the plants, showing a positive correlation to the density increase of glandular trichomes. RT-PCR analysis showed that progeny of self-pollinated plants expressed the amorpha-4, 11-diene synthase (ADS) and cytochrome P450 monooxygenase 71 AV1 (CYP71AV1) genes, which are involved in artemisinin biosynthesis in leaves and flowers. The use of self-pollinated A. annua plants will be a valuable approach to the study of artemisinin biosynthesis.}, number={4}, journal={PLANTA}, author={Alejos-Gonzalez, Fatima and Qu, Guosheng and Zhou, Li-Li and Saravitz, Carole H. and Shurtleff, Janet L. and Xie, De-Yu}, year={2011}, month={Oct}, pages={685–697} }
 @article{qu_nues_watkins_maxwell_2011, title={The Spatial-Functional Coupling of Box C/D and C '/D ' RNPs Is an Evolutionarily Conserved Feature of the Eukaryotic Box C/D snoRNP Nucleotide Modification Complex}, volume={31}, ISSN={["1098-5549"]}, DOI={10.1128/mcb.00918-10}, abstractNote={ABSTRACT Box C/D ribonucleoprotein particles guide the 2′-O-ribose methylation of target nucleotides in both archaeal and eukaryotic RNAs. These complexes contain two functional centers, assembled around the C/D and C′/D′ motifs in the box C/D RNA. The C/D and C′/D′ RNPs of the archaeal snoRNA-like RNP (sRNP) are spatially and functionally coupled. Here, we show that similar coupling also occurs in eukaryotic box C/D snoRNPs. The C/D RNP guided 2′-O-methylation when the C′/D′ motif was either mutated or ablated. In contrast, the C′/D′ RNP was inactive as an independent complex. Additional experiments demonstrated that the internal C′/D′ RNP is spatially coupled to the terminal box C/D complex. Pulldown experiments also indicated that all four core proteins are independently recruited to the box C/D and C′/D′ motifs. Therefore, the spatial-functional coupling of box C/D and C′/D′ RNPs is an evolutionarily conserved feature of both archaeal and eukaryotic box C/D RNP complexes.}, number={2}, journal={MOLECULAR AND CELLULAR BIOLOGY}, author={Qu, Guosheng and Nues, Rob W. and Watkins, Nicholas J. and Maxwell, E. Stuart}, year={2011}, month={Jan}, pages={365–374} }
 @article{gagnon_zhang_qu_biswas_suryadi_brown_maxwell_2010, title={Signature amino acids enable the archaeal L7Ae box C/D RNP core protein to recognize and bind the K-loop RNA motif}, volume={16}, ISSN={["1469-9001"]}, DOI={10.1261/rna.1692310}, abstractNote={The archaeal L7Ae and eukaryotic 15.5kD protein homologs are members of the L7Ae/15.5kD protein family that characteristically recognize K-turn motifs found in both archaeal and eukaryotic RNAs. In Archaea, the L7Ae protein uniquely binds the K-loop motif found in box C/D and H/ACA sRNAs, whereas the eukaryotic 15.5kD homolog is unable to recognize this variant K-turn RNA. Comparative sequence and structural analyses, coupled with amino acid replacement experiments, have demonstrated that five amino acids enable the archaeal L7Ae core protein to recognize and bind the K-loop motif. These signature residues are highly conserved in the archaeal L7Ae and eukaryotic 15.5kD homologs, but differ between the two domains of life. Interestingly, loss of K-loop binding by archaeal L7Ae does not disrupt C′/D′ RNP formation or RNA-guided nucleotide modification. L7Ae is still incorporated into the C′/D′ RNP despite its inability to bind the K-loop, thus indicating the importance of protein–protein interactions for RNP assembly and function. Finally, these five signature amino acids are distinct for each of the L7Ae/L30 family members, suggesting an evolutionary continuum of these RNA-binding proteins for recognition of the various K-turn motifs contained in their cognate RNAs.}, number={1}, journal={RNA}, author={Gagnon, Keith T. and Zhang, Xinxin and Qu, Guosheng and Biswas, Shyamasri and Suryadi, Jimmy and Brown, Bernard A., II and Maxwell, E. Stuart}, year={2010}, month={Jan}, pages={79–90} }