title: Characterization of LEF4 ligand binding property and its role as part of baculoviral transcription machinery.
abstract: Late expression factor 4 (LEF4) is one of the four identified subunits of Autographa californica nucleopolyhedrosis virus (AcNPV) encoded RNA polymerase that carries out transcription from viral late and very late promoters. This 464-amino acid baculovirus-encoded protein also harbors 5' mRNA capping activity that includes RNA 5' triphosphatase, nucleoside triphosphatase, and guanylyltransferase activities. Hydrolysis of 5' triphosphate RNA and free NTPs is metal ion dependent property of the protein. In the present communication, we describe the structural changes in the recombinant LEF4 protein following ligand binding. Metal ion binding causes some alteration in the conformation around aromatic amino acids whereas there is no effect on tryptophan fluorescence on GTP binding in absence and presence of metal ion. It is found that GTP and divalent cation cofactor produce some prominent changes in the secondary structure of the protein. Electrophoretic mobility shift assay (EMSA) shows that LEF4 is the probable factor that acts as anchor to dock the viral RNA polymerase on the very late polyhedrin promoter (Ppolh) facilitated by other factors.
authors.affiliation: Department of Biochemistry, University of Hyderabad, Gachibowli, Hyderabad, 500 046, India.
authors.forename: Sheeba
authors.initials: S
authors.lastname: Rasheedi
authors.forename: Madhuri
authors.initials: M
authors.lastname: Suragani
authors.forename: Soghra K
authors.initials: SK
authors.lastname: Haq
authors.forename: Sudip
authors.initials: S
authors.lastname: Ghosh
authors.forename: Nasreen Z
authors.initials: NZ
authors.lastname: Ehtesham
authors.forename: Seyed E
authors.initials: SE
authors.lastname: Hasnain
mesh_terms: D016367:Baculoviridae / Q000737:chemistry* / Q000235:genetics; D012321:DNA-Directed RNA Polymerases; D008024:Ligands; D008670:Metals / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012315:RNA Caps; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D008024:Ligands; D008670:Metals; D012315:RNA Caps; D014764:Viral Proteins; C471155:late gene expression factor 4, Bombyx mori nucleopolyhedrovirus; D012321:DNA-Directed RNA Polymerases