MAX E. GOTTESMAN

We study the E. coli virus, lambda, and its relatives. Our focus has been the inhibition of lambda gene expression by phage HK022 Nun protein. Nun, which is related to the HIV TAT protein, binds to specific sequences in lambda nascent mRNA and blocks translocation of RNA polymerase. Nun also contacts lambda DNA template just promoter-distal to the stalled RNA polymerase. We are interested in the detailed biochemistry of this reaction and its role in the life cycle of HK022.

We also study how cAMP signals are transduced to different parts of the eukaryotic cell. The subcellular location of PKA is of critical importance in transmission of these signals. PKA is localized to different subcellular compartments by a family of anchoring proteins, the AKAPs. The relationship between PKA anchoring and cAMP signal tranduction is being studied in purified cell-free systems and in cultured cell lines. In several cell lines, expression of AKAP75 enhances the nuclear response to cAMP. Finally, AKAP121, which anchors PKA to the outer mitochondrial membrane and is essential for preventing apoptosis, tethers the mRNA for the mitochondrial Fo-f subunit of ATPsynthase and the mRNA encoding MnSOD. Binding is PKA dependent, implying that the import of mitochondrial proteins may respond to cAMP signals. In fact, AKAP121 expression and cAMP treatment significantly increase mitochondrial MnSOD content.

The role of cAMP in cell cycle progression in a cycling Xenopus oocyte extract is under investigation. We find that cAMP and cAMP-dependent Protein Kinase (PKA) levels oscillate, and these fluctuations are essential for cycle progression. Neither the signal that induces cyclic AMP, nor the target of the activated PKA is yet known.

We are also interested in the role of serum retinol binding protein (RBP) in vitamin A metabolism. As a model system, we have generated a mouse that lacks serum retinol binding protein (RBP). This mouse is born blind, but regains sight on a normal diet. It cannot, however, mobilize liver vitamin A stores and is always on the threshold of vitamin A deficiency. Mutant mothers, deprived of vitamin A, generate abnormal embryos. The mice also show evidence of benign prostatic hypertrophy.

Recent and Notable Articles

Nudler, E. and Gottesman, M.E. Transcription Termination and Antitermination in E. Coli. Genes to Cells 7(8):755-768 (2002).

Quadro, L., Blaner, W.S., Hamberger, L., Van Gelder, R.N., Vogel, S., Piantedosi, R., Gouras, P., Colantuoni, V., and Gottesman, M.E. Muscle expression of human retinol-binding protein (RBP). J. Biol Chem. 277:30191-30197. (2002).

Vogel, S., Piantedosi, R., Byrne, S.M., Kako, Y., Quadro, L., Gottesman, M.E., Goldberg, I.J., and Blaner, W.S. Retinol-Binding Protein-Deficient Mice: Biochemical Basis for Impaired Vision. Biochemistry 41:15360-15368 (2002).

Costanzo, V., Shechter, D., Lupardus, P.J., Cimprich, K.A., Gottesman, M. and Gautier, J. An ATR- and Cdc7-dependent DNA damage checkpoint that inhibits initiation of DNA replication. Mol. Cell, 11:203-213 (2003).

Kim, H.C., Zhou, Z-G., Wilson, H.R., Mogilnitskiy, G., Court, D.L.. and Gottesman, M.E. Phage HK022 Nun protein represses translation of phage l N. Proc Natl Acad Sci U S A 100(9):5308-12 (2003).

Ginsberg, M.D., Feliciello, A., Jones, J.K., Avvedimento, E.V., and Gottesman, M.E. PKA-dependent binding of mRNA to the mitochondrial AKAP121 protein. J. Mol. Biol. 327(4):885-8997. (2003).

Washburn, R.S., Wong, Y., and Gottesman, M.E. Role of E. coli Transcription-repair coupling factor Mfd in Nun-mediated transcription termination. J. Mol. Biol. 329:655-662 (2003).

Affaitati A, Cardone L, de Cristofaro T, Carlucci A, Ginsberg MD, Varrone S, Gottesman ME, Avvedimento EV, Feliciello A. Essential role of A-kinase anchor protein 121 for cAMP signaling to mitochondria. J Biol Chem. 278(6):4286-94 (2003).