53-mediated apoptosis in insect cells (230). Flag-tagged P33 displays a diffuse cytoplasmic localization and punctuate nuclear staining in the absence of P53. In the presence of P53, P33 has an entirely nuclear localization. An insect p53 homolog has been identified (208) and many DNA viruses encode a P53 binding protein. Mass spectrometry indicated that P33 may be present in ODV particles (20).
Ac93: ac93, unknown function
The ac93 ORF is transcribed (287) and encodes a 18.4 kDa (161 aa) protein of unknown function, also named P18 in other baculoviruses. The conserved region is addressed as a DUF628 domain in the CDD (176).
Ac94: odv-e25, occlusion-derived virus envelope protein
ODV-E25 (25.5 kDa, 228 aa) is an integral ODV envelope protein, that is N-terminally anchored in the envelope (249). ODV-E25 is also present in BVs, but is much less abundant there than in ODVs (239). The ODV-E25 protein is initially present at a low concentrations, but is present at a higher levels from 36 h p.i. onwards (239). The N-terminal amino acid sequence of the protein (24 amino acids) is highly hydrophobic and this hydrophobic domain is sufficient to direct ODV-E25 to virus-induced membrane micro-vesicles within the nucleus and the ODV viral envelope (104).
Ac95: helicase, DNA helicase
Ac95 is a baculovirus core gene and encodes a 143.2 kDa (1221 aa) polypeptide (P143) with a consensus NTP-binding site and six other motifs characteristic for helicase proteins. Ac95 is a delayed early gene, which is transactivated by IE-1 (ac147) and PE38 (ac153) with a stimulatory role of IE-2 (ac151) (163). A ts-mutant showed the essential role of P143 in viral DNA replication (165) and this was further confirmed by transient replication assays (133). The AcMNPV helicase shows specificity for AcMNPV replication and cannot be exchanged with the SeMNPV helicase in transient DNA replication assays (98).
Ac96: ac96, unknown function
Ac96 is a baculovirus core gene encoding a 19.8 kDa (173 aa) protein. The BmNPV homolog Bm79 encodes a larger, 28 kDa protein, which is located in the ODV-envelope (ODV-E28) (286). The conserved region of Ac96 is indicated as the baculovirus 19 kDa protein superfamily domain. AcMNPV ac96 is found within a four-gene cluster comprising of helicase, lef-5, ac96, and 38K (ac98). The relative positions of these genes are conserved in all baculovirus genomes (100).
Ac97: ac97, unknown function
Ac97 is predicted to be an early gene encoding a 6.5 kDa (56 aa) protein. A transcript overlaps this ORF (287). Homologs of this gene with unknown function have not been found in other baculoviruses (Table 2 and Table 3).
Ac98: 38k, 38K protein
The gene ac98 encodes the protein 38K (38.0 kDa, 320 aa) which is synthesized in the late phase of infection. The 38K protein is localized and distributed over the cylindrical sheath of the nucleocapsid of both BVs and ODVs and is required for nucleocapsid assembly, but not for DNA replication (281, 282). Furthermore, it interacts with the nucleocapsid proteins VP1054 (ac54), VP39 (ac89), VP80 (ac104) and itself (281). The ac98 belongs to the baculovirus core genes (Table 2 and Table 3).
Ac99: lef-5, Late expression factor 5
The gene ac99 codes for the late expression factor LEF-5 (31.0 kDa, 265 aa), which has significant sequence similarity in a stretch of 32 C-terminal amino acids with a zinc ribbon domain in the eukaryotic transcription elongation factor TFIIS (95). Unlike the cellular TFIIS, LEF-5 functions most likely as a transcription initiation factor and stimulates transcription mediated by baculovirus RNA polymerase from late and very late viral promoters at least in in vitro transcription assays (83).. The N terminal 194 amino acids are involved in LEF-5:LEF-5 self interactions and the 32 C-terminal amino acids of LEF-5 contain a putative Zn2+-ribbon domain (95). The acidic dipeptide DE within this domain is crucial for LEF-5 activity (83). Lef-5 is a core gene (Table 2 and Table 3).
Ac100: p6.9, major DNA-binding protein
The most abundant protein in the nucleoprotein core is a small (6.9 kDa