Controlled atmospheres and sugar can delay malate synthase gene expression during asparagus senescence

2002 ◽  
Vol 29 (9) ◽  
pp. 1045 ◽  
Author(s):  
Simon A. Coupe ◽  
Ben K. Sinclair ◽  
Sheryl D. Somerfield ◽  
Paul L. Hurst

A cDNA clone encoding malate synthase (MS; EC 4.1.3.2) was isolated from a 48-h postharvest asparagus (Asparagus officinalis L.) spear cDNA library using a MS clone from Brassica napus. The asparagus MS (AoMS1) cDNA hybridized to a 1.9-kb transcript that increased in abundance preferentially in spear-tip tissue during postharvest storage. The AoMS1 transcript also accumulated during natural foliar senescence of asparagus fern. The cDNA consists of 1960 nucleotides with an open reading frame of 1665 nucleotides or 555 amino acids, and encodes a deduced protein with a predicted Mr of 63 kDa and a pI of 8.1. The deduced amino acid sequence of AoMS1 showed high identity with the B. napus MS clone (77.2%) used to isolate it, and with MS from cucumber (77%). Genomic Southern analysis suggests that a single gene in asparagus encodes AoMS1. Controlled- atmosphere treatments aimed at reducing deterioration of harvested asparagus spears reduced the expression of AoMS1. The reduction was correlated with the reduced oxygen level, and reduced MS enzyme activity was also observed. Asparagus cell cultures were used to test the role of sugar status in regulating AoMS1 gene expression. In cultures without sucrose there was an accumulation of AoMS1 transcript that was absent in cultures containing sucrose.

2002 ◽  
Vol 76 (22) ◽  
pp. 11612-11622 ◽  
Author(s):  
Kersten T. Hall ◽  
Mathew S. Giles ◽  
Michael A. Calderwood ◽  
Delyth J. Goodwin ◽  
David A. Matthews ◽  
...  

ABSTRACT The role of the gamma-2 herpesvirus open reading frame (ORF) 73 gene product has become the focus of considerable interest. It has recently been shown that the Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA) is expressed during a latent infection and can modulate both viral and cellular gene expression. The herpesvirus saimiri (HVS) ORF 73 gene product has some sequence homology to LANA; however, the role of HVS ORF 73 is unknown. We have previously demonstrated that HVS ORF73 is expressed in a stably transduced human carcinoma cell line, where HVS genomes persist as nonintegrated circular episomes. This implies that there may be some functional homology between these proteins. To further investigate the role of the HVS ORF 73 protein, the yeast two-hybrid system was employed to identify interacting cellular proteins. We demonstrate that ORF 73 interacts with the cellular protein p32 and triggers the accumulation of p32 in the nucleus. Using reporter gene-based transient-transfection assays, we demonstrate that ORF 73 can transactivate a number of heterologous promoter constructs and also upregulate its own promoter. Moreover, ORF 73 and p32 act synergistically to transactivate these promoters. The binding of ORF 73 to p32 is mediated by an amino-terminal arginine-rich domain, which contains two functionally distinct nuclear localization signals. The p32 binding domains are required for ORF 73 transactivating abilities and for ORF 73 to induce nuclear accumulation of p32. These results suggest that ORF 73 can function as a regulator of gene expression and that p32 is involved in ORF 73-dependent transcriptional activation.


2005 ◽  
Vol 73 (7) ◽  
pp. 4391-4394 ◽  
Author(s):  
Ambrose L. Cheung ◽  
Adhar C. Manna

ABSTRACT The global regulatory locus sarA comprises a 375-bp open reading frame that is driven by three promoters, the proximal P1 and distal P3 and P2 promoters. We mutated the weaker P3 and P2 promoters to ascertain the effect of the change on SarA protein and target gene expression. Our results indicated that the solely active P1 promoter led to a lower SarA protein level, which has an effect on agr transcription and subsequently had corresponding effects on hla, sspA, and spa transcription, probably in both agr-independent and agr-dependent manners.


1988 ◽  
Vol 8 (9) ◽  
pp. 3898-3905 ◽  
Author(s):  
C Huxley ◽  
T Williams ◽  
M Fried

The mouse surfeit locus is unusual in that it contains a number of closely clustered genes (Surf-1, -2, and -4) that alternate in their direction of transcription (T. Williams, J. Yon, C. Huxley, and M. Fried, Proc. Natl. Acad. Sci. USA 85:3527-3530, 1988). The heterogeneous 5' ends of Surf-1 and Surf-2 are separated by 15 to 73 base pairs (bp), and the 3' ends of Surf-2 and Surf-4 overlap by 133 bp (T. Williams and M. Fried, Mol. Cell. Biol. 6:4558-4569, 1986; T. Williams and M. Fried, Nature (London) 322:275-279, 1986). A fourth gene in this locus, Surf-3, which is a member of a multigene family, has been identified. The poly(A) addition site of Surf-3 lies only 70 bp from the poly(A) addition site of Surf-1. Transcription of Surf-3 has been studied in the absence of the other members of its multigene family after transfection of a cloned genomic mouse DNA fragment, containing the Surf-3 gene, into heterologous monkey cells. Surf-3 specifies a highly expressed 1.0-kilobase mRNA that contains a long open reading frame of 266 amino acids, which would encode a highly basic polypeptide (23% Arg plus Lys). The other members of the Surf-3 multigene family are predominantly, if not entirely, intronless pseudogenes with the hallmarks of being generated by reverse transcription. The role of the very tight clustering on regulation of expression of the genes in the surfeit locus is discussed.


1998 ◽  
Vol 72 (1) ◽  
pp. 857-861 ◽  
Author(s):  
Adrian Whitehouse ◽  
Matthew Cooper ◽  
David M. Meredith

ABSTRACT The herpesvirus saimiri (HVS) immediate-early gene product encoded by open reading frame (ORF) 57 shares limited amino acid homology with HSV-1 ICP27 and Epstein-Barr virus BMLF1, both regulatory proteins. The ORF 57 gene has been proposed to be spliced based on the genome sequence, and here we confirm the intron-exon structure of the gene. We also demonstrate that a cDNA construct of the ORF 57 gene product represses the transactivating capability of the ORF 50a gene product (which is produced from a spliced transcript), but activates that of ORF 50b (an unspliced transcript). Further analyses with cotransfection experiments show that ORF 57 can either activate or repress expression from a range of both early and late HVS promoters, depending on the target gene. These results indicate that repression of gene expression mediated by the ORF 57 gene product is dependent on the presence of an intron within the target gene encoding region. Furthermore, Northern blot analysis demonstrates that the levels of mRNA transcribed from genes not containing an intron are not significantly affected in the presence of the ORF 57 gene product. This suggests that it regulates gene expression through a posttranscriptional mechanism.


2005 ◽  
Vol 79 (7) ◽  
pp. 4308-4315 ◽  
Author(s):  
Arti Gaur ◽  
William R. Green

ABSTRACT LP-BM5 murine leukemia virus-infected C57BL/6 mice develop profound immunodeficiency and B-cell lymphomas. The LP-BM5 complex contains a mixture of defective (BM5def) and replication-competent helper viruses among which BM5def is the primary causative agent of disease. The BM5def primary open reading frame (ORF1) encodes the single gag precursor protein (Pr60 gag ). Our lab has recently demonstrated that a novel immunodominant cytotoxic-T-lymphocyte (CTL) epitope (SYNTGRFPPL) is expressed from a +1-nucleotide translational open reading frame of BM5def during the course of normal retrovirus expression. The SYNTGRFPPL CTL epitope may be generated from either of two initiation methionines present, ORF2a or ORF2b, located downstream of the ORF1 initiation site. This study investigates the role(s) of the alternative ORF2-derived gag protein(s) of BM5def in viral pathogenesis. We have examined the disease-inducing capabilities of mutant viruses in which the translational potential of either the initiating ORF2a or ORF2b AUG has been disrupted. Although these mutated viruses are capable of wild-type ORF1 expression, they are unable to induce disease. Our data strongly suggest the existence of a novel ORF2 product(s) that is required for LP-BM5-induced pathogenesis and have potentially broad implications for other retroviral diseases.


Genome ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. 757-760 ◽  
Author(s):  
Ronald A. Butow ◽  
Hong Zhu ◽  
Philip Perlman ◽  
Heather Conrad-Webb

All mRNAs on the yeast mitochondrial genome terminate at a conserved dodecamer sequence 5′-AAUAAUAUUCUU-3′. We have characterized two mutants with altered dodecamers. One contains a deletion of the dodecamer at the end of the var1 gene, and the other contains two adjacent transversions in the dodecamer at the end of the reading frame of fit1, a gene within the ω+ allele of the 21S rRNA gene. In each mutant, expression of the respective gene is blocked completely. A dominant nuclear suppressor, SUV3-1, was isolated that suppresses the var1 deletion but is without effect on the fit1 dodecamer mutations. Unexpectedly, however, we found that SUV3-1 blocks expression of the wild-type fit1 allele by blocking processing at its dodecamer. SUV3-1 has pleiotropic effects on mitochondrial gene expression, affecting RNA processing, RNA stability, and translation. Our results suggest that RNA metabolism and translation may be part of a multicomponent complex within mitochondria.Key words: mitochondria, yeast, mRNA, RNA processing, 3′ dodecamer.


2011 ◽  
Vol 89 (5) ◽  
pp. 489-494 ◽  
Author(s):  
Austin E Gillen ◽  
Ann Harris

The CCCTC-binding factor (CTCF), which binds insulator elements in vertebrates, also facilitates coordinated gene expression at several gene clusters, including the β-globin, Igf2/H19 (insulin like growth factor 2/H19 noncoding RNA), and major histocompatibility complex (MHC) class II loci. CTCF controls expression of these genes both by enabling insulator function and facilitating higher order chromatin interactions. While the role of CTCF in gene regulation is best studied at these multi-gene loci, there is also evidence that CTCF contributes to the regulated expression of single genes. Here, we discuss how CTCF participates in coordinating gene expression at the CFTR (cystic fibrosis transmembrane conductance regulator) and IFNG (interferon-gamma) loci. We consider the structural similarities between the loci with regard to CTCF-binding elements, the possible interaction between nuclear receptors and CTCF, and the role of CTCF in chromatin looping at these genes. These comparisons reveal a functional model that may be applicable to other single-gene loci that require CTCF for coordinated gene expression.


2000 ◽  
Vol 66 (2) ◽  
pp. 476-480 ◽  
Author(s):  
Sang Jun Lee ◽  
Dong Min Kim ◽  
Kwang Hee Bae ◽  
Si Myung Byun ◽  
Jae Hoon Chung

ABSTRACT Staphylokinase (SAK), a polypeptide secreted byStaphylococcus aureus, is a plasminogen activator with a therapeutic potential in thrombosis diseases. A Bacillus subtilis strain which is multiply deficient in exoproteases was transformed by an expression plasmid carrying a promoter and a signal sequence of subtilisin fused in frame with the sak open reading frame. However, the amount of SAK secretion was marginal (45 mg/liter). In contrast, disruption of the wprA gene, which encodes a subtilisin-type protease, strongly promoted the production of SAK in the stationary phase (181 mg/liter). In addition, the extracellular stability of mature SAK was dramatically enhanced. These data indicate a significant role of the wprA gene product in degrading foreign proteins, both during secretion and in the extracellular milieu.


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