Characterization of HCF‐1, a determinant of <i>Autographa californica</i> multiple nucleopolyhedrovirus host specificity

Hefferon, Kathleen

doi:10.1046/j.1365-2583.2003.00451.x

Cited by 9 publications

(10 citation statements)

References 33 publications

(46 reference statements)

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“…Interestingly, a previous report showed self-association activity by HCF-1 truncation mutants which would have lacked cysteine residues which we found to be essential for this activity (19). These data suggest the possibility that other regions of the HCF-1 protein may also be capable of self-association activity.…”

Section: Discussionsupporting

confidence: 63%

“…Since RING-containing proteins are often involved in protein-protein interactions, we analyzed the possibility that HCF-1 may bind to other late expression factors. We and others did not detect significant binding of HCF-1 to other late expression factors using the conditions described (19; data not shown), we have observed significant binding of HCF-1 with itself (19). We transfected cells with plasmids that express either N-terminally HA.11 epitope-tagged versions of CAT or HCF-1 or a Cterminally HA.11-tagged HCF-1 and subsequently infected with a virus that expresses either a Flag-tagged version of HCF-1 or a Flag-tagged version of CAT.…”

Section: Resultssupporting

confidence: 54%

“…In a previously published report, HCF-1 was found to be expressed as an early protein in the nucleus of infected cells (19). In addition, HCF-1 was found to be capable of self-association.…”

mentioning

confidence: 77%

“…Results published previously (19) indicated that regions essential to the function of HCF-1 reside throughout the protein.…”

mentioning

confidence: 86%

“…Mutational analysis using HCF-1 truncations showed that activity in transient late expression assays was abolished by deletion of any region of HCF-1 with the exception of the C-terminal 33 amino acids. In addition, self-association activity was found to be located at the N terminus of the protein (19).…”

mentioning

confidence: 99%

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Expression and Mutational Analysis of Autographa californica Nucleopolyhedrovirus HCF-1: Functional Requirements for Cysteine Residues

Jw¹,

Forney²,

Ricci³

et al. 2005

J Virol

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The host cell-specific factor 1 gene (hcf-1) of the baculovirus Autographa californica multiple nucleopolyhedrovirus is required for efficient virus growth in TN368 cells but is dispensable for virus replication in SF21 cells. However, the mechanism of action of hcf-1 is unknown. To begin to understand its function in virus replication we have investigated the expression and localization pattern of HCF-1 in infected cells. Analysis of virus-infected TN368 cells showed that hcf-1 is expressed at an early time in the virus life cycle, between 2 and 12 h postinfection, and localized the protein to punctate nuclear foci. Through coprecipitation experiments we have confirmed that HCF-1 self-associates into dimers or higher-order structures. We also found that overexpression of HCF-1 repressed expression from the hcf-1 promoter in transient reporter assays. Mutagenesis of cysteine residues within a putative RING finger domain in the amino acid sequence of HCF-1 abolished self-association activity and suggests that the RING domain may be involved in this protein-protein interaction. A different but overlapping set of cysteine residues were required for efficient gene repression activity. Functional analysis of HCF-1 mutants showed that the cysteine amino acids required for both self-association and gene repression activities of HCF-1 were also required for efficient late-gene expression and occlusion body formation in TN368 cells. Mutational analysis also identified essential charged and hydrophobic amino acids located between two of the essential cysteine residues. We propose that HCF-1 is a RING finger-containing protein whose activity requires HCF-1 self-association and gene repression activity.The family Baculovirudae is a diverse group of viruses that infect primarily insects. Baculoviruses are used routinely as expression vectors but are also interesting because of their potential use as biological insecticides (32). Most baculovirus species infect a narrow range of host insects. The type baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is unusual in that it has a host range that spans many insect genera (9). It is important to understand the molecular biology of baculovirus host range and cell type-specific restriction so that it may be possible to predict the effects of genetically modified viruses on nonhost species.The host range of baculoviruses is restricted at a stage subsequent to virus entry into cells. Free virus particles are capable of entering a wide variety of permissive and nonpermissive insect and mammalian cells, however, levels of early gene expression, DNA replication, and late-gene expression vary depending on the cell line (34, 35). In non-and semipermissive cells, including human liver cells, DNA is released into the nucleus in an expressible form (21, 35). However, in nonpermissive cells no DNA replication or late-gene expression occurs. Thus, the block to virus replication in nonpermissive insect cells appears to occur subsequent to early-gene expression.To date, s...

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Section: Discussionsupporting

confidence: 63%

Section: Resultssupporting

confidence: 54%

mentioning

confidence: 77%

“…Results published previously (19) indicated that regions essential to the function of HCF-1 reside throughout the protein.…”

mentioning

confidence: 86%

mentioning

confidence: 99%

See 3 more Smart Citations

Expression and Mutational Analysis of Autographa californica Nucleopolyhedrovirus HCF-1: Functional Requirements for Cysteine Residues

Jw¹,

Forney²,

Ricci³

et al. 2005

J Virol

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Functional analysis of the Autographa californica nucleopolyhedrovirus IAP1 and IAP2

et al. 2009

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The Autographa californica nucleopolyhedrovirus (AcMNPV) contains three apoptosis suppressor genes: p35, iap1 and iap2. AcMNPV P35 functions as a pancaspase inhibitor, but the function of IAP1 and IAP2 has not been entirely resolved. In this paper, we analyze the function of IAP1 and IAP2 in detail. AcMNPV with p35-deletion inhibited the apoptosis of BTI-Tn-5B1-4 (Tn-Hi5) cells induced by a Helicoverpa armigera single nucleocapsid NPV (HearNPV) infection and rescued the replication of HearNPV and BV production in these cells. Transient-expression experiments indicated that both IAP1 and IAP2 suppress apoptosis of Tn-Hi5 cells during HearNPV infection. Recombinant HearNPVs expressing AcMNPV iap1, iap2 and p35, respectively, not only prevented apoptosis but also allowed HearNPV to replicate in Tn-Hi5 cells. However, the iap1, iap2 and p35 genes when expressed in HearNPV were unable to rescue BV production. These results indicate that both AcMNPV iap1 and iap2 function independently as apoptosis inhibitors of and are potential host range factors.

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Baculovirus host-range

Thiem

Cheng

2009

Virol. Sin.

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Characterization of HCF‐1, a determinant of Autographa californica multiple nucleopolyhedrovirus host specificity

Cited by 9 publications

References 33 publications

Expression and Mutational Analysis of Autographa californica Nucleopolyhedrovirus HCF-1: Functional Requirements for Cysteine Residues

Expression and Mutational Analysis of Autographa californica Nucleopolyhedrovirus HCF-1: Functional Requirements for Cysteine Residues

Functional analysis of the Autographa californica nucleopolyhedrovirus IAP1 and IAP2

Baculovirus host-range

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