Robert W. Simons 

Department of Microbiology, Immunology, and Molecular Genetics

 
Research Interests: Translational control and RNA structure
Work in this laboratory is concerned primarily with the regulation of gene expression in Escherichia coli, with a current emphasis on translational control and RNA structure. A primary area has to do with antisense RNAs, which are small diffusible transcripts that pair to complementary regions on target mRNAs, thereby inhibiting translation. We are interested in how antisense RNA/mRNA structure influences this process. We have a broad interest in RNA structure, especially as it relates to translation initiation. Intramolecular structures that sequester a translation initiation site can block ribosome binding. Our goal is to define how fast such structure form, and what folding pathway they follow. We recently extended these studies to include the self-cleaving hammerhead ribozyme. Many RNA structures are recognized and bound by specific proteins, which in turn alter the RNA's function. We are exploring how ribonucleases bind to and process messenger RNAs, thereby regulating their expression. Ribonuclease III regulates its own expression by cleaving the leader of its mRNA. We are pursuing this mechanism in detail, as well as exploring the involvement of an essential G-protein, which appears to regulate ribonuclease III activity under certain conditions. Our fourth and newest area focusses on translation initiation factor III, which binds to ribosomes, helps to select the initiator tRNA and scans the codon/anticodon interaction to insure accuracy. Our goal is to define factor function more precisely, eventually at the structural level.

 

Selected Recent Publications:

Sussman, J.K., Simons, E.L. and Simons, R.W. (1996) Escherichia coli
translation initiation factor 3 discriminates the initiation codon in
vivo.  Molec. Microbiol. 21:347-360.

Matsunaga, J., Simons, E.L. and Simons, R.W.  (1996) RNase III
autoregulation:  Structure and function of rncO, the posttranscriptional
"operator".  RNA 2:1228-1240.

Matsunaga, J., Dyer, M., Simons, E.L. and Simons, R.W.  (1996)
Expression and regulation of the rnc and pdxJ operons of Escherichia
coli.  Molec. Microbiol. 22:977-989.

Anderson, P.E., Matsunaga, J., Simons, E.L. and Simons, R.W. (1996)
Structure and regulation of the Salmonella typhimurium rnc-era-recO
operon.  Biochimie 78:1025-1034.

Pepe, C.M., Suzuki, C., Laurie, C. and Simons, R.W. (1997) Regulation of
the "tetCD" genes of transposon Tn10.  J. Mol. Biol. 270:14-25.

Babic, S., Hunter, C.N., Rakhlin, N.J., Simons, R.W. and Phillips-Jones,
M.K. (1997) Molecular characterisation of the pifC gene encoding
translation initiation factor 3, which is required for normal
photosynthetic complex formation in Rhodobacter sphaeroides NCIB 8253.
Eur. J. Biochem. 249:564-575.

Matsunaga, J., Simons, E.L. and Simons, R.W.  (1997) E. coli RNase III
(rnc) autoregulation occurs independently of rnc gene translation.
Molec. Microbiol. 26:1127.

Simons, R.W. and Grunberg-Manago, M., eds. (1998) RNA Structure and
Function.  Cold Spring Harbor Press, Cold Spring Harbor, NY.  741p.

Zeiler, B.N. and Simons, R.W. (1998).  Antisense RNA structure and
function.  In:  RNA Structure and Function, R.W. Simons and M.
Grunberg-Manago, Eds.  Cold Spring Harbor Press, Cold Spring Harbor, NY,
pp 437-464.

Robert Simons
(310) 825-8890
bobs@microbio.ucla.edu