Ramachandra R. Reddy, Ph.D.
Professor, Department of Pharmacology
Education and Awards
- Ph.D., 1969, Center for Cellular and Molecular Biology, Hyderabad, India
Syntesis of Small Nuclear RNAs: Functions of Post-Transcriptional Modifications
The trimethylguanosine (TMG)-capped snRNA genes are transcribed by RNA polymerase II, whereas methylphosphate (MpppG)-capped snRNAs are transcribed by RNA polymerase III. However, the TMG and Mppp cap structures are not functionally interchangeable. We showed that the methylphosphate cap structure is present in many small RNAs and this cap structure enhances the stability of these RNAs up to 10-fold. We also found that when methylphosphate cap structure is introduced into small RNAs that normally contain a triphosphate on their 5' ends, the stability of the small RNAs is improved. The methylphosphate cap is formed post-transcriptionally in the nucleus and a signal present on the 5' ends in all the methylphosphate capped RNAs directs this cap formation. We recently purified a 130-kDa nuclear enzyme that is responsible for the methylphosphate cap formation.
The focus of the lab is to obtain the recombinant capping enzyme and study the capping enzyme: RNA substrate interactions. In addition, we plan to introduce the capping signals present in small RNAs into mRNAs so that T7 RNA polymerase-transcribed mRNAs in eukaryotic cells can acquire the methylphosphate cap and have improved stability. The improved stability of these mRNAs is expected to increase the yield of recombinant proteins expressed in eukaryotic cells.
- Chen, Y., Sinha, K., Perumal, K., Gu, J., and Reddy, R. (1998) Accurate 3'-end processing and adenylation of human signal recognition particle RNA and Alu RNA in vitro. J. Biol. Chem. 273:35023-35031.
- Sinha, K., Gu, J., Chen, Y., and Reddy, R. (1998) Adenylation of small RNAs in human cells. J. Biol. Chem. 273:6853-6859.
- Gu J, Shumyatsky G, Makan N and Reddy R: (1997) Formation of 2í-3í-cyclic phosphates at the 3í-end of human U6 small nuclear RNA in vitr Identification of 2í-3í-cyclic phosphates at the 3í-ends of human SRP and MRP RNAs. J. Biol. Chem. 272:21989-21993.
- Gu,J., Patton, J., Shimba, S., and Reddy, R. (1996) Localization of modified nucleotides in yeast (S. pombe) spliceosomal small nuclear RNAs: Modified nucleotides are clustered in functionally important regions. RNA 2:909-918.
- Reddy R and Shimba S: (1996) Structural and functional similarities between MRP and RNaseP. Molecular Biology Reports. 9:3-5.
- Shimba, S., Bokar, J.A., Rottman, F., and Reddy, R. (1995) Accurate and efficient N-6-adenosine methylation in spliceosomal U6 snRNA by HeLa cell extract in vitro. Nucl. Acids Res. 13:2421-2426.
- Shimba, S. and Reddy, R. (1994) Purification of Human U6 RNA Capping Enzyme: Evidence for a Common Capping Enzyme for g-Monomethyl phosphate-Capped Small RNAs. J. Biol. Chem. 269: 12419-12423.
- Shumyatsky, G., Wright, D., and Reddy, R. (1994) Methylphosphate Cap Structure increases the Stability of 7SK, B2 and U6 RNAs in Frog Oocytes. Nucl. Acids Res. 21:4756-4761.
- Liu, M., Busch, Rose, Buckley, B., and Reddy, R. (1992) Characterization of Antibodies against Methyl-pppN Cap Structure: Plant U3 Small Nucleolar RNA is recognized by these Antibodies. Nucl. Acids Res. 20:4299-4304.
- Reddy, R., Singh, R., and Shimba, S. (1992) Methylated cap structures: Structure and Functions. Pharm. Therapeutics. 54:249-267.
- Singh, R. and Reddy, R. (1989) g-Monomethyl Phosphate : A Cap Structure in Spliceosomal U6 Small Nuclear RNA. Proc. Natl. Acad. Sci. USA 86:8280-8283.