The roles of eighteen baculovirus late expression factor genes in transcription and DNA replication

Abstract

A set of 18 plasmid subclones of the Autographa californica nuclear polyhedrosis virus genome supports expression from a late viral promoter in transient expression assays (J. W. Todd, A. L. Passarelli, and L. K. Miller, J. Virol. 69:968-974, 1995). Using this set of plasmids, we have assigned a role for each of the 18 genes required for optimal late gene expression with respect to its involvement at the levels of transcription, translation, and/or DNA replication. RNase protection analyses demonstrated that all of the known late expression factor genes (lefs) affected the steady-state level of reporter gene RNA. Thus, none of the lefs appeared to be specifically involved in translation. A subset of the lefs supported plasmid replication; ie-1, lef-1, lef-2, lef-3, p143, and p35 were essential for plasmid replication, while ie-n, lef-7, and dnapol had stimulatory effects. The predicted sequence of lef-7 suggests that it is a homolog of herpesvirus single-stranded DNAbinding protein (UL29). The role of p35 in plasmid replication appears to be suppression of apoptosis, because p35 could be functionally replaced in the replication assay by either Cp-iap or Op-iap, two heterologous baculovirus genes which suppress apoptosis by a mechanism which appears to differ from that of p35. Thus, one or more of the replication-related lefs or the process of plasmid replication appears to induce cellular apoptosis. Our results indicate that the remaining lefs, lefs 4 through 11, p47, and 39K (pp31), function either at the level of transcription or at that of mRNA stabilization.

The Baculoviruses Occlusion‐Derived Virus: Virion Structure and Function

“…The nucleocapsids of ODVs have consequentially evolved to carry with them viral DNA replication factors along with the viral genome. The six core baculovirus DNA replication proteins are immediate early 1 (IE-1), DNA polymerase (DNApol), P143 (helicase), LEF-1 (primase), LEF-2 (primase cofactor), and LEF-3 (single-stranded DNA-binding protein or SSB) (Kool et al, 1994;Lu and Miller, 1995b). ODV nucleocapsids contain all of these proteins but for LEF-2 (Braunagel et al, 2003).…”

“…The IE-1 protein is not only involved in DNA replication but is also a highly conserved transcriptional activator of viral genes (Choi and Guarino, 1995a,b,c;Kremer and Knebel-Morsdorf, 1998;Passarelli and Miller, 1993) and is also a required component of viral DNA replication complex (Kool et al, 1994;Lu and Miller, 1995b). IE-1 predominantly localizes in the virogenic stroma where DNA replication occurs (Kawasaki et al, 2004).…”

Reconstructing the replication complex of AcMNPV

“…IE2, LEF-7 and P35 are stimulatory, but not essential, during AcMNPV replication in Sf-21 cells and not required at all in Tn-368 cells [6]. IE2 and P35 were not examined any further because these factors appeared unlikely to have a direct interaction with other replication LEFs.…”

Genome-wide diversity in temporal and regional populations of the betabaculovirusErinnyis ello granulovirus(ErelGV)

“…The lef-10 has shown to be the most polymorphic lef gene (12.92×10 -3 NSS/bp). This gene encodes a short protein that is probably a component of a multisubunit RNA polymerase [45]. Although lef- 10 vp1054.…”