2475 TAMU
College Station, TX 77843-2475

Office:
Biochemistry/Biophysics Bldg.
Room 333A
979-845-7556

Lab:
Biochemistry/Biophysics Bldg.
Room 330
979-845-7560

Fax: 979-845-9274
Email: l-guarino@tamu.edu

Research in this laboratory is directed toward understanding the regulation of gene expression in baculovirus-infected cells. Temporal regulation of viral genes requires the sequential expression of an immediate early gene(s) to activate delayed early gene expression; and a late gene(s) to stimulate polyhedrin, a very late gene. A complementation assay was devised to map the viral factors that control the temporal regulation of each phase of viral infection. Expression of delayed early genes is regulated by at least three factors: trans-activator and a cis-acting enhancer. The molecular mechanisms by which these three factors regulate gene expression currently is under investigation. This research involves an analysis of DNA-protein interactions, construction of viral mutants, site-directed mutagenesis and transcriptional regulation. This research should provide insights into the mechanisms that regulate viral development and gene expression as well as increase our knowledge concerning the functions of cis- and trans-activating factors.

Another project concerns the function of a baculovirus protein with high homology to the eukaryotic protein ubiquitin. Ubiquitin is highly conserved and varies by only three amino acids between mammals, yeast and plants. The viral protein, however, differs from mammalian ubiquitin at 18 amino acid residues, although many of the residues known to be essential for ubiquitin function have been conserved. This raises interesting questions with respect to why the viral protein has diverged from eukaryotic protein ubiquitin and why the virus encodes its own ubiquitin gene when ubiquitin is already present in the host cell. The basic goal of this project is to answer the questions, "What is the function of viral ubiquitin and how is that function related to the amino acid sequence?" We intend to address these questions through the use of monoclonal antibodies specific for the host and viral ubiquitins; construction of ubiquitin-deficient viral mutants; and in vitro assays of ubiquitin function using purified viral and host proteins.

Guarino, L.A. and L. Ross. 1997. Cycloheximide inhibition of baculovirus early gene expression. Virology 232: 105-113.

Guarino, L.A., G. Smith, and W. Dong. 1995. Ubiquitin is attached to membranes of baculovirus particles by a novel type of phospholipid anchor. Cell 80: 301-309.

Guarino, L.A., and B.S. Yoo Xu. 1995. Differential transcription of baculovirus late and very late promoters: Fractionation of nuclear extracts by phosphocellulose chromatography. J. Virol 69: 2912-2917.

Guarino, L.A. and J.C. Choi. 1995. A temperature-sensitive IE1 protein of Autographa californica nuclear polyhedrosis virus has altered DNA binding activity. Virology 209: 90-98.