scholarly journals Characterization of late gene expression factors lef-9 and lef-8 from Bombyx mori nucleopolyhedrovirus

2002 ◽  
Vol 83 (8) ◽  
pp. 2015-2023 ◽  
Author(s):  
Asha Acharya ◽  
Karumathil P. Gopinathan
Keyword(s):  
Gene Expression ◽  
Bombyx Mori ◽  
Late Gene ◽  
Late Gene Expression ◽  
Reading Frame ◽  
Early Transcription ◽  
A Site ◽  
Translational Termination

Late gene expression factors, LEF-4, LEF-8, LEF-9 and P47 constitute the primary components of the Autographa californica multinucleocapsid polyhedrovirus (AcMNPV)-encoded RNA polymerase, which initiates transcription from late and very late promoters. Here, characterization of lef-9 and lef-8, which encode their corresponding counterparts, from Bombyx mori NPV is reported. Transcription of lef-9 initiated at two independent sites: from a GCACT sequence located at −38 nt and a CTCTT sequence located at −50 nt, with respect to the +1 ATG of the open reading frame. The 3′ end of the transcript was mapped to a site 17 nt downstream of a canonical polyadenylation signal located 7 nt downstream of the first of the two tandem translational termination codons. Maximum synthesis of LEF-9 was seen from 36 h post-infection (p.i.). The transcription of lef-8 initiated early in infection from a GTGCAAT sequence that differed in the corresponding region from its AcMNPV counterpart (GCGCAGT), with consequent elimination of the consensus early transcription start site motif (underlined). Peak levels of lef-8 transcripts were attained by 24 h p.i. Immunocopurification analyses suggested that there was an association between LEF-8 and LEF-9 in vivo.

Characterization of late gene expression factor LEF-10 from Bombyx mori nucleopolyhedrovirus

2013 ◽  
Vol 175 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Wei Yu ◽  
Chao-Yi Du ◽  
Yan-Ping Quan ◽  
Zuo-Ming Nie ◽  
Jian Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bombyx Mori ◽  
Late Gene ◽  
Late Gene Expression ◽  
Bombyx Mori Nucleopolyhedrovirus

Cloning and characterization of theddsAgene encoding decaprenyl diphosphate synthase fromRhodobacter capsulatusB10

2006 ◽  
Vol 52 (12) ◽  
pp. 1141-1147 ◽  
Author(s):  
Xinyi Liu ◽  
Haizhen Wu ◽  
Jiang Ye ◽  
Qinsheng Yuan ◽  
Huizhan Zhang
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Rhodobacter Capsulatus ◽  
Open Reading Frame ◽  
High Similarity ◽  
Reading Frame ◽  
Endogenous Production ◽  
Genome Library

A decaprenyl diphosphate synthase gene (ddsA, GenBank accession No. DQ191802) was cloned from Rhodobacter capsulatus B10 by constructing and screening the genome library. An open reading frame of 1002 bp was revealed from sequence analysis. The deduced polypeptide consisted of 333 amino acids residues with an molecular mass of about 37 kDa. The DdsA protein contained the conserved amino acid sequence (DDXXD) of E-type polyprenyl diphosphate synthase and showed high similarity to others. In contrast, DdsA showed only 39% identity to a solanesyl diphosphate synthase cloned from R. capsulatus SB1003. DdsA was expressed successfully in Escherichia coli. Assaying the enzyme in vivo found it made E.coli synthesize UQ-10 in addition to the endogenous production UQ-8.Key words: ubiquinone, polyprenyl diphosphate synthase, gene expression, Rhodobacter capsulatus.

trans Activation of the simian virus 40 late transcription unit by T-antigen

1985 ◽  
Vol 5 (6) ◽  
pp. 1391-1399
Author(s):  
J Brady ◽  
G Khoury
Keyword(s):  
Gene Expression ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Transcription Unit ◽  
T Antigen ◽  
Late Gene ◽  
Antigen Binding ◽  
Late Gene Expression ◽  
Antigen Binding Site

We have investigated the role of simian virus 40 (SV40) T-antigen in the induction of late gene expression independent of its function in amplifying templates through DNA replication. Northern blot and S1 nuclease analyses showed that stimulation occurred at the transcriptional level. At least two template elements, the T-antigen-binding sites and the 72-base-pair repeats, appeared to be important for this induction. Using template mutants, we demonstrated that deletions within T-antigen-binding site II decreased T-antigen-mediated late gene expression approximately 10- to 20-fold. In addition, multiple point mutations within a single retained copy of the SV40 72-base-pair repeat decreased T-antigen-mediated late gene expression. Using in vivo competition studies, we demonstrated that competitor DNA fragments containing the SV40 control region (nucleotides 5171 through 272) quantitatively decreased SV40 late gene expression in COS-1 cells. In contrast, competition with a plasmid containing SV40 nucleotides 1 through 294 (which removes all of T-antigen-binding site I and half of site II) was much less efficient. Finally, we demonstrated that in vivo competition experiments employing competitor fragments distal to the T-antigen-binding sites within the late template region (SV40 nucleotides 180 through 2533) resulted in superinduction of late gene expression in COS-1 cells. This finding suggests that negative factors such as repressors or attenuators may modulate late SV40 gene expression before induction. Our results are consistent with a model in which induction of late gene expression involves an interaction of the SV40 origin region with DNA-binding proteins, one of which may be T-antigen. Activation of the SV40 late transcription unit may involve induction of the SV40 enhancer or removal of a repressor-like protein or both.

scholarly journals Extended Function of Plasmid Partition Genes: the Sop System of Linear Phage-Plasmid N15 Facilitates Late Gene Expression

2008 ◽  
Vol 190 (10) ◽  
pp. 3538-3545 ◽  
Author(s):  
Nikolai V. Ravin ◽  
Jérôme Rech ◽  
David Lane
Keyword(s):  
Gene Expression ◽  
Late Gene ◽  
Northern Hybridization ◽  
Partition Functions ◽  
Wild Type ◽  
Late Promoter ◽  
Late Gene Expression ◽  
Reading Frame ◽  
Partition System ◽  
Plasmid Partition

ABSTRACT The mitotic stability of the linear plasmid-prophage N15 of Escherichia coli depends on a partition system closely related to that of the F plasmid SopABC. The two Sop systems are distinguished mainly by the arrangement of their centromeric SopB-binding sites, clustered in F (sopC) and dispersed in N15 (IR1 to IR4). Because two of the N15 inverted repeat (IR) sites are located close to elements presumed (by analogy with phage λ) to regulate late gene expression during the lytic growth of N15, we asked whether Sop partition functions play a role in this process. In N15, a putative Q antiterminator gene is located 6 kb upstream of the probable major late promoter and two intrinsic terminator-like sequences, in contrast to λ, where the Q gene is adjacent to the late promoter. Northern hybridization and lacZ reporter activity confirmed the identity of the N15 late promoter (p52), demonstrated antiterminator activity of the Q analogue, and located terminator sequences between p52 and the first open reading frame. Following prophage induction, N15 mutated in IR2 (downstream from gene Q) or IR3 (upstream of p52) showed a pronounced delay in lysis relative to that for wild-type N15. Expression of ir3 −-p52::lacZ during N15 wild-type lytic growth was strongly reduced relative to the equivalent ir3 + fusion. The provision of Q protein and the IR2 and SopAB proteins in trans to ir3 +-p52::lacZ increased expression beyond that seen in the absence of any one of these factors. These results indicate that the N15 Sop system has a dual role: partition and regulation of late gene transcription during lytic growth.

scholarly journals Differentiation-Dependent Chromatin Rearrangement Coincides with Activation of Human Papillomavirus Type 31 Late Gene Expression

2001 ◽  
Vol 75 (20) ◽  
pp. 10005-10013 ◽  
Author(s):  
Loren del Mar Peña ◽  
Laimonis A. Laimins
Keyword(s):  
Gene Expression ◽  
Dnase I ◽  
Human Papillomaviruses ◽  
Open Reading Frame ◽  
Late Gene ◽  
Late Gene Expression ◽  
Reading Frame ◽  
Undifferentiated Cells ◽  
Late Transcript ◽  
Chromatin Rearrangement

ABSTRACT The life cycle of human papillomaviruses (HPVs) is tightly linked to the differentiation status of the host cell. While early genes are expressed during the initial stages of viral infection, late gene expression occurs in the suprabasal layers of the cervical epithelium. Late genes encode E1^E4, a cytosolic protein, and capsid proteins L1 and L2. We have mapped over 30 initiation sites for late transcripts and show that the transcripts initiate in a 200-nucleotide region within the E7 open reading frame. The mechanisms regulating the activation of late gene expression, however, are not yet understood. DNase I hypersensitivity analysis of HPV-31 chromatin in cell lines that maintain viral genomes extrachromosomally indicates that a major shift in nuclease digestion occurs upon differentiation. In undifferentiated cells, hypersensitive regions exist in the upstream regulatory region proximal to the E6 open reading frame. Upon differentiation, a region between nucleotides 659 and 811 in the E7 open reading frame becomes accessible to DNase I. These results indicate that the late transcript initiation region becomes accessible to transcription factor binding upon differentiation. Several complexes mediate chromatin rearrangement, and we tested whether histone acetylation was sufficient for late transcript activation. Treatment with the histone deacetylase inhibitor trichostatin A was found to be insufficient to activate late gene expression in undifferentiated cells. However, it did activate expression of early transcripts. These results suggest that chromatin remodeling around the late promoter occurs upon epithelial differentiation and that mechanisms in addition to histone deacetylation contribute to activation of late gene expression.

scholarly journals Early c-Fos Induction after Cerebral Ischemia: A Possible Neuroprotective Role

2001 ◽  
Vol 21 (5) ◽  
pp. 550-556 ◽  
Author(s):  
Sunghee Cho ◽  
Eun-Mi Park ◽  
Yoonseong Kim ◽  
Nian Liu ◽  
Judit Gal ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cerebral Ischemia ◽  
Fusion Gene ◽  
Glucose Deprivation ◽  
Late Gene ◽  
Late Gene Expression ◽  
Ca1 Neurons ◽  
Fos Expression

The role of c-Fos in neurodegeneration or neuroprotection after cerebral ischemia is controversial. To investigate whether early c-Fos induction after ischemia is associated with neuroprotection, rats were subjected to 10 minutes of transient forebrain ischemia and c-Fos expression was examined. Resistant dentate granule cells and neurons in CA2–4 displayed more robust immunoreactivity than vulnerable neurons in the CA1 region of hippocampus during early hours of reperfusion. By 6 hours after reperfusion, c-Fos immunoreactivity was greatly diminished in all areas of the hippocampus. Administration of N-acetyl-O-methyldopamine (NAMDA), a compound previously shown to protect CA1 neurons against ischemia, increased c-Fos immunoreactivity in the CA1 vulnerable region at 6 hours after ischemia and protected SK-N-BE(2)C neurons from oxygen glucose deprivation. Further in vitro study showed that NAMDA potentiated phorbol-12 myristate-13 acetate (PMA)-induced c-Fos expression, AP1 binding activity, and late gene expression determined by chloramphenicol acetyltransferase (CAT) activity from AP1 containing tyrosine hydroxylase promoter-CAT fusion gene in SK-N-BE(2)C neurons. In vivo and in vitro results showed that a neuroprotectant, NAMDA, in concert with another stimulus (for example, ischemia or PMA) up-regulates c-Fos expression and suggested that the early rise of NAMDA-induced c-Fos expression in vulnerable CA1 neurons may account for neuroprotection by means of up-regulating late gene expression for survival.

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