1
|
Abstract
The T box riboswitch is an intriguing potential target for antibacterial drug discovery. Found primarily in Gram-positive bacteria, the riboswitch regulates gene expression by selectively responding to uncharged tRNA to control transcription readthrough. Polyamines and molecular crowding are known to specifically affect RNA function, but their effect on T box riboswitch efficacy and tRNA affinity have not been fully characterized. A fluorescence-monitored in vitro transcription assay was developed to readily quantify these molecular interactions and to provide a moderate-throughput functional assay for a comprehensive drug discovery screening cascade. The polyamine spermidine specifically enhanced T box riboswitch readthrough efficacy with an EC50 = 0.58 mM independent of tRNA binding. Molecular crowding, simulated by the addition of polyethylene glycol, had no effect on tRNA affinity for the riboswitch, but did reduce the efficacy of tRNA-induced readthrough. These results indicate that the T box riboswitch tRNA affinity and readthrough efficacy are intricately modulated by environmental factors.
Collapse
|
2
|
Gupta K, Mattingly SJ, Knipp RJ, Afonin KA, Viard M, Bergman JT, Stepler M, Nantz MH, Puri A, Shapiro BA. Oxime ether lipids containing hydroxylated head groups are more superior siRNA delivery agents than their nonhydroxylated counterparts. Nanomedicine (Lond) 2015; 10:2805-18. [PMID: 26107486 PMCID: PMC4636123 DOI: 10.2217/nnm.15.105] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
AIM To evaluate the structure-activity relationship of oxime ether lipids (OELs) containing modifications in the hydrophobic domains (chain length, degree of unsaturation) and hydrophilic head groups (polar domain hydroxyl groups) toward complex formation with siRNA molecules and siRNA delivery efficiency of resulting complexes to a human breast cancer cell line (MDA-MB-231). MATERIALS & METHODS Ability of lipoplex formation between oxime ether lipids with nucleic acids were examined using biophysical techniques. The potential of OELs to deliver nucleic acids and silence green fluorescent protein (GFP) gene was analyzed using MDA-MB-231 and MDA-MB-231/GFP cells, respectively. RESULTS & CONCLUSION Introduction of hydroxyl groups to the polar domain of the OELs and unsaturation into the hydrophobic domain favor higher transfection and gene silencing in a cell culture system.
Collapse
Affiliation(s)
- Kshitij Gupta
- Gene Regulation & Chromosome Biology Lab, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | | | - Ralph J Knipp
- Department of Chemistry, University of Louisville, Louisville, KY 40292, USA
| | - Kirill A Afonin
- Gene Regulation & Chromosome Biology Lab, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
- Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA
| | - Mathias Viard
- Basic Research Lab, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
- Basic Science Program, Leidos Biomedical Research, Inc., National Cancer Institute, Center for Cancer Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21702-1201, USA
| | - Joseph T Bergman
- Gene Regulation & Chromosome Biology Lab, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Marissa Stepler
- Gene Regulation & Chromosome Biology Lab, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Michael H Nantz
- Department of Chemistry, University of Louisville, Louisville, KY 40292, USA
| | - Anu Puri
- Gene Regulation & Chromosome Biology Lab, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Bruce A Shapiro
- Gene Regulation & Chromosome Biology Lab, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| |
Collapse
|