scholarly journals Towards the Creation of a Transgenic Possum Parasite

2021 ◽  
Author(s):  
◽  
Jan Newton-Howes

<p>The brushtail possum. Trichosurus vulpecula, is New Zealand's most serious vertebrate pest; possums destroy native flora and fauna and are vectors of bovine Tb. Conventional control is considered to be unsustainable and, in the long term, biological control is seen as the only solution to reducing possum numbers. The aim of this project is to contribute to the development of a self-disseminating vector that will spread a control molecule throughout the possum population reducing fecundity or increasing mortality. The possum-specific parasite Parastrongyloides trichosuri has considerable potential a-s such a vector. A protein from P. trichosuri specifically, was found to be antigenic in possums. The antibodies to this protein were purified from positive possum serum and used to detect the antigen on the surface of infective larvae but not in the excretory/secretory products of either larvae or adults. The protein was isolated from crude infective larvae and found to show homology to the heat-shock 70 family of proteins. Genomic DNA was extracted, an oligonucleotide probe made and a genomic library screened for the Hsp70 gene. Several positive clones were found and DNA isolated and sequenced from one such clone. Five kilo bases of unambiguous sequence was obtained in which was an open reading frame of 2 kb. Theoretical translation of this gave a protein of 64 amino acids with 80% homology to the Hsp70A protein of C. elegans. The region upstream of the ATG initiator codon was amplified and 1.3 kb of the putative promoter region was cloned into a vector containing the gfp:lacZ reporter genes. This construct was microinjected, first into C. elegans to demonstrate promoter function, and then into both tree-living and parasitic adults of P. trichosuri. Reporter gene expression was shown in the progeny of microinjected parasitic adults. RNA was made from infective P. trichosuri larvae, reverse transcribed and the coding sequence for the PtHsp70 protein cloned into an expression vector and expressed in E. coli, The recombinant protein pattern had a similar pattern of trypsin digestion products as the native protein, as shown by MALDI-TOF mass spectrometry, but it was immunologically distinct from the native protein. The culmination of this project was the generation of a transgenic P trichosuri, the first vertebrate endoparasitic nematode to be heritably transformed. This is a necessary step in the development of a self-disseminating vector to be used in the biocontrol of possums.</p>

2021 ◽  
Author(s):  
◽  
Jan Newton-Howes

<p>The brushtail possum. Trichosurus vulpecula, is New Zealand's most serious vertebrate pest; possums destroy native flora and fauna and are vectors of bovine Tb. Conventional control is considered to be unsustainable and, in the long term, biological control is seen as the only solution to reducing possum numbers. The aim of this project is to contribute to the development of a self-disseminating vector that will spread a control molecule throughout the possum population reducing fecundity or increasing mortality. The possum-specific parasite Parastrongyloides trichosuri has considerable potential a-s such a vector. A protein from P. trichosuri specifically, was found to be antigenic in possums. The antibodies to this protein were purified from positive possum serum and used to detect the antigen on the surface of infective larvae but not in the excretory/secretory products of either larvae or adults. The protein was isolated from crude infective larvae and found to show homology to the heat-shock 70 family of proteins. Genomic DNA was extracted, an oligonucleotide probe made and a genomic library screened for the Hsp70 gene. Several positive clones were found and DNA isolated and sequenced from one such clone. Five kilo bases of unambiguous sequence was obtained in which was an open reading frame of 2 kb. Theoretical translation of this gave a protein of 64 amino acids with 80% homology to the Hsp70A protein of C. elegans. The region upstream of the ATG initiator codon was amplified and 1.3 kb of the putative promoter region was cloned into a vector containing the gfp:lacZ reporter genes. This construct was microinjected, first into C. elegans to demonstrate promoter function, and then into both tree-living and parasitic adults of P. trichosuri. Reporter gene expression was shown in the progeny of microinjected parasitic adults. RNA was made from infective P. trichosuri larvae, reverse transcribed and the coding sequence for the PtHsp70 protein cloned into an expression vector and expressed in E. coli, The recombinant protein pattern had a similar pattern of trypsin digestion products as the native protein, as shown by MALDI-TOF mass spectrometry, but it was immunologically distinct from the native protein. The culmination of this project was the generation of a transgenic P trichosuri, the first vertebrate endoparasitic nematode to be heritably transformed. This is a necessary step in the development of a self-disseminating vector to be used in the biocontrol of possums.</p>


Genetics ◽  
2000 ◽  
Vol 155 (3) ◽  
pp. 1105-1117 ◽  
Author(s):  
W John Haynes ◽  
Kit-Yin Ling ◽  
Robin R Preston ◽  
Yoshiro Saimi ◽  
Ching Kung

Abstract Pawn mutants of Paramecium tetraurelia lack a depolarization-activated Ca2+ current and do not swim backward. Using the method of microinjection and sorting a genomic library, we have cloned a DNA fragment that complements pawn-B (pwB/pwB). The minimal complementing fragment is a 798-bp open reading frame (ORF) that restores the Ca2+ current and the backward swimming when expressed. This ORF contains a 29-bp intron and is transcribed and translated. The translated product has two putative transmembrane domains but no clear matches in current databases. Mutations in the available pwB alleles were found within this ORF. The d4-95 and d4-96 alleles are single base substitutions, while d4-662 (previously pawn-D) harbors a 44-bp insertion that matches an internal eliminated sequence (IES) found in the wild-type germline DNA except for a single C-to-T transition. Northern hybridizations and RT-PCR indicate that d4-662 transcripts are rapidly degraded or not produced. A second 155-bp IES in the wild-type germline ORF excises at two alternative sites spanning three asparagine codons. The pwB ORF appears to be separated from a 5′ neighboring ORF by only 36 bp. The close proximity of the two ORFs and the location of the pwB protein as indicated by GFP-fusion constructs are discussed.


1997 ◽  
Vol 323 (2) ◽  
pp. 547-555 ◽  
Author(s):  
Vincent A. McKIE ◽  
Gary W. BLACK ◽  
Sarah J. MILLWARD-SADLER ◽  
Geoffrey P. HAZLEWOOD ◽  
Judith I. LAURIE ◽  
...  

Pseudomonas fluorescens subsp. cellulosa expressed arabinanase activity when grown on media supplemented with arabinan or arabinose. Arabinanase activity was not induced by the inclusion of other plant structural polysaccharides, and was repressed by the addition of glucose. The majority of the Pseudomonas arabinanase activity was extracellular. Screening of a genomic library of P. fluorescens subsp. cellulosa DNA constructed in Lambda ZAPII, for recombinants that hydrolysed Red-dyed arabinan, identified five arabinan-degrading plaques. Each of the phage contained the same Pseudomonas arabinanase gene, designated arbA, which was present as a single copy in the Pseudomonas genome. The nucleotide sequence of arbA revealed an open reading frame of 1041 bp encoding a protein, designated arabinanase A (ArbA), of Mr 39438. The N-terminal sequence of ArbA exhibited features typical of a prokaryotic signal peptide. Analysis of the primary structure of ArbA indicated that, unlike most Pseudomonas plant cell wall hydrolases, it did not contain linker sequences or have a modular structure, but consisted of a single catalytic domain. Sequence comparison between the Pseudomonas arabinanase and proteins in the SWISS-PROT database showed that ArbA exhibits greatest sequence identity with arabinanase A from Aspergillus niger, placing the enzyme in glycosyl hydrolase Family 43. The significance of the differing substrate specificities of enzymes in Family 43 is discussed. ArbA purifed from a recombinant strain of Escherichia coli had an Mr of 34000 and an N-terminal sequence identical to residues 32–51 of the deduced sequence of ArbA, and hydrolysed linear arabinan, carboxymethylarabinan and arabino-oligosaccharides. The enzyme displayed no activity against other plant structural polysaccharides, including branched sugar beet arabinan. ArbA produced almost exclusively arabinotriose from linear arabinan and appeared to hydrolyse arabino-oligosaccharides by successively releasing arabinotriose. ArbA and the Aspergillus arabinanase mediated a decrease in the viscosity of linear arabinan that was associated with a significant release of reducing sugar. We propose that ArbA is an arabinanase that exhibits both an endo- and an exo- mode of action.


2004 ◽  
Vol 384 (1) ◽  
pp. 129-137 ◽  
Author(s):  
Benjamin ABO-DALO ◽  
Dieudonne NDJONKA ◽  
Francesco PINNEN ◽  
Eva LIEBAU ◽  
Kai LÜERSEN

The putative diamine N-acetyltransferase D2023.4 has been cloned from the model nematode Caenorhabditis elegans. The 483 bp open reading frame of the cDNA encodes a deduced polypeptide of 18.6 kDa. Accordingly, the recombinantly expressed His6-tagged protein forms an enzymically active homodimer with a molecular mass of approx. 44000 Da. The protein belongs to the GNAT (GCN5-related N-acetyltransferase) superfamily, and its amino acid sequence exhibits considerable similarity to mammalian spermidine/spermine-N1-acetyltransferases. However, neither the polyamines spermidine and spermine nor the diamines putrescine and cadaverine were efficiently acetylated by the protein. The smaller diamines diaminopropane and ethylenediamine, as well as L-lysine, represent better substrates, but, surprisingly, the enzyme most efficiently catalyses the N-acetylation of amino acids analogous with L-lysine. As determined by the kcat/Km values, the C. elegans N-acetyltransferase prefers thialysine [S-(2-aminoethyl)-L-cysteine], followed by O-(2-aminoethyl)-L-serine and S-(2-aminoethyl)-D,L-homocysteine. Reversed-phase HPLC and mass spectrometric analyses revealed that N-acetylation of L-lysine and L-thialysine occurs exclusively at the amino moiety of the side chain. Remarkably, heterologous expression of C. elegans N-acetyltransferase D2023.4 in Escherichia coli, which does not possess a homologous gene, results in a pronounced resistance against the anti-metabolite thialysine. Furthermore, C. elegans N-acetyltransferase D2023.4 exhibits the highest homology with a number of GNATs found in numerous genomes from bacteria to mammals that have not been biochemically characterized so far, suggesting a novel group of GNAT enzymes closely related to spermidine/spermine-N1-acetyltransferase, but with a distinct substrate specificity. Taken together, we propose to name the enzyme ‘thialysine Nε-acetyltransferase’.


1991 ◽  
Vol 11 (12) ◽  
pp. 5801-5812
Author(s):  
R A Preston ◽  
M F Manolson ◽  
K Becherer ◽  
E Weidenhammer ◽  
D Kirkpatrick ◽  
...  

The Saccharomyces cerevisiae PEP3 gene was cloned from a wild-type genomic library by complementation of the carboxypeptidase Y deficiency in a pep3-12 strain. Subclone complementation results localized the PEP3 gene to a 3.8-kb DNA fragment. The DNA sequence of the fragment was determined; a 2,754-bp open reading frame predicts that the PEP3 gene product is a hydrophilic, 107-kDa protein that has no significant similarity to any known protein. The PEP3 predicted protein has a zinc finger (CX2CX13CX2C) near its C terminus that has spacing and slight sequence similarity to the adenovirus E1a zinc finger. A radiolabeled PEP3 DNA probe hybridized to an RNA transcript of 3.1 kb in extracts of log-phase and diauxic lag-phase cells. Cells bearing pep3 deletion/disruption alleles were viable, had decreased levels of protease A, protease B, and carboxypeptidase Y antigens, had decreased repressible alkaline phosphatase activity, and contained very few normal vacuolelike organelles by fluorescence microscopy and electron microscopy but had an abundance of extremely small vesicles that stained with carboxyfluorescein diacetate, were severely inhibited for growth at 37 degrees C, and were incapable of sporulating (as homozygotes). Fractionation of cells expressing a bifunctional PEP3::SUC2 fusion protein indicated that the PEP3 gene product is present at low abundance in both log-phase and stationary cells and is a vacuolar peripheral membrane protein. Sequence identity established that PEP3 and VPS18 (J. S. Robinson, T. R. Graham, and S. D. Emr, Mol. Cell. Biol. 11:5813-5824, 1991) are the same gene.


Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 97-112 ◽  
Author(s):  
I Pinto ◽  
J G Na ◽  
F Sherman ◽  
M Hampsey

Abstract The cyc1-362 mutant of Saccharomyces cerevisiae is deficient in iso-1-cytochrome c as a consequence of an aberrant ATG codon that initiates a short open reading frame (uORF) in the cyc1 transcribed leader region. We have isolated and characterized functional revertants of cyc1-362 in an effort to define cis- and trans-acting factors that can suppress the effect of the uORF. Genetic and DNA sequence analyses have defined three classes of revertants: (i) those that acquired point mutations in the upstream ATG (uATG), restoring iso-1-cytochrome c to its normal level; (ii) substitution of the normal A residue at position -1 relative to the uATG by either C or T, enhancing iso-1-cytochrome c production from approximately 2% to 6% (C) or 10% (T) of normal, indicating that the nucleotide immediately preceding the initiator codon can affect the efficiency of AUG start codon recognition and that purines are preferred over pyrimidines at this site; and (iii) extragenic suppressors that enhance iso-1-cytochrome c expression to 10-40% of normal while retaining the uATG. These suppressors are represented by five different genes, designated sua1-sua4 and sua6. In contrast to the previously described sua7 and sua8 suppressors, they do not compensate for the uATG by affecting cyc1 transcription start site selection. Potential suppressor mechanisms are discussed.


1990 ◽  
Vol 10 (8) ◽  
pp. 4221-4232
Author(s):  
B Repetto ◽  
A Tzagoloff

Yeast mutants assigned to the pet complementation group G104 were found to lack alpha-ketoglutarate dehydrogenase activity as a result of mutations in the dihydrolipoyl transsuccinylase (KE2) component of the complex. The nuclear gene KGD2, coding for yeast KE2, was cloned by transformation of E250/U6, a G104 mutant, with a yeast genomic library. Analysis of the KGD2 sequence revealed an open reading frame encoding a protein with a molecular weight of 52,375 and 42% identities to the KE2 component of Escherichia coli alpha-ketoglutarate dehydrogenase complex. Disruption of the chromosomal copy of KGD2 in a respiratory-competent haploid yeast strain elicited a growth phenotype similar to that of G104 mutants and abolished the ability to mitochondria to catalyze the reduction of NAD+ by alpha-ketoglutarate. The expression of KGD2 was transcriptionally regulated by glucose. Northern (RNA) analysis of poly(A)+ RNA indicated the existence of two KGD2 transcripts differing in length by 150 nucleotides. The concentrations of both RNAs were at least 10 times lower in glucose (repressed)- than in galactose (derepressed)-grown cells. Different 5'-flanking regions of KGD2 were fused to the lacZ gene of E. coli in episomal plasmids, and the resultant constructs were tested for expression of beta-galactosidase in wild-type yeast cells and in hap2 and hap3 mutants. Results of the lacZ fusion assays indicated that transcription of KGD2 is activated by the HAP2 and HAP3 proteins. The regulated expression of KGD2 was found to depend on sequences that map to a region 244 to 484 nucleotides upstream of the structural gene. This region contains two short sequence elements that differ by one nucleotide from the consensus core (5'-TN[A/G]TTGGT-3') that has been proposed to be essential for binding of the HAP activation complex. These data together with earlier reports on the regulation of the KGD1 and LPD1 genes for the alpha-ketoglutarate and dihydrolipoyl dehydrogenases indicate that all three enzyme components of the complex are catabolite repressed and subject to positive regulation by the HAP2 and HAP3 proteins.


1998 ◽  
Vol 64 (9) ◽  
pp. 3411-3415 ◽  
Author(s):  
Yo-Shen Chen ◽  
James L. Steele

ABSTRACT A previously identified insert expressing an endopeptidase from aLactobacillus helveticus CNRZ32 genomic library was characterized. Nucleotide sequence analysis revealed an open reading frame of 1,941 bp encoding a putative protein of 71.2 kDa which contained a zinc-protease motif. Protein homology searches revealed that this enzyme has 40% similarity with endopeptidase O (PepO) fromLactococcus lactis P8-2-47. Northern hybridization revealed that pepO is monocistronic and is expressed throughout the growth phase. CNRZ32 derivatives lacking PepO activity were constructed via gene replacement. Enzyme assays revealed that the PepO mutant had significantly reduced endopeptidase activity when compared to CNRZ32 with two of the three substrates examined. Growth studies indicated that PepO has no detectable effect on growth rate or acid production by Lactobacillus helveticusCNRZ32 in amino acid defined or skim milk medium.


1998 ◽  
Vol 44 (7) ◽  
pp. 657-666 ◽  
Author(s):  
Phillip Aldridge ◽  
Frank Bernhard ◽  
Peter Bugert ◽  
David L Coplin ◽  
Klaus Geider

In a genomic library of Erwinia amylovora, a locus has been identified that can suppress an Erwinia stewartii rcsA mutant. In addition, the locus induced a mucoid sticky phenotype of colonies in a wild-type strain of Erwinia stewartii and increased exopolysaccharide synthesis in several species of bacteria belonging to the genus Erwinia. An open reading frame was identified at this locus encoding a 225 amino acid protein that contained a helix-turn-helix motif typical of transcriptional regulators. The corresponding gene was subsequently named rcsV (regulator of capsular synthesis affecting viscosity). A mutant of rcsV in wild-type Erwinia amylovora had no detectable phenotype and produced typical levels of amylovoran under laboratory conditions. The rcsV gene on a high copy number plasmid under the control of its own promoter did not alter amylovoran production, in contrast to in-frame fusions of the structural gene in expression vectors. Since even the lac promoter was inert in the expression of rcsV, a DNA-binding protein could inhibit transcription of the gene in Erwinia amylovora. On the other hand, an Erwinia amylovora rcsA mutant was suppressed by rcsV when its promoter was replaced and the structural gene fused in-frame with lacZ' or malE. Northern blots, with total RNA from Erwinia amylovora, or promoter analysis using the GUS reporter gene did not show expression of rcsV in Erwinia amylovora, although primer extension analysis did. RcsV could be a component involved in the regulation of amylovoran synthesis, and gene expression may require an unknown external signal during the life cycle or pathogenesis of Erwinia amylovora. Key words: amylovoran, fire blight, rcsA-like activator, fusion protein.


1992 ◽  
Vol 285 (3) ◽  
pp. 947-955 ◽  
Author(s):  
J E Rixon ◽  
L M A Ferreira ◽  
A J Durrant ◽  
J I Laurie ◽  
G P Hazlewood ◽  
...  

A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA constructed in pUC18 and expressed in Escherichia coli was screened for recombinants expressing 4-methylumbelliferyl beta-D-glucoside hydrolysing activity (MUGase). A single MUGase-positive clone was isolated. The MUGase hydrolysed cellobiose, cellotriose, cellotetraose, cellopentaose and cellohexaose to glucose, by sequentially cleaving glucose residues from the non-reducing end of the cello-oligosaccharides. The Km values for cellobiose and cellohexaose hydrolysis were 1.2 mM and 28 microM respectively. The enzyme exhibited no activity against soluble or insoluble cellulose, xylan and xylobiose. Thus the MUGase is classified as a 1,4-beta-D-glucan glucohydrolase (EC 3.2.1.74) and is designated 1,4-beta-D-glucan glucohydrolase D (CELD). When expressed by E. coli, CELD was located in the cell-envelope fraction; a significant proportion of the native enzyme was also associated with the cell envelope when synthesized by its endogenous host. The nucleotide sequence of the gene, celD, which encodes CELD, revealed an open reading frame of 2607 bp, encoding a protein of M(r) 92,000. The deduced primary structure of CELD was confirmed by the M(r) of CELD (85,000) expressed by E. coli and P. fluorescens subsp. cellulosa, and by the experimentally determined N-terminus of the enzyme purified from E. coli, which showed identity with residues 52-67 of the celD translated sequence. The structure of the N-terminal region of full-length CELD was similar to the signal peptides of P. fluorescens subsp. cellulosa plant-cell-wall hydrolases. Deletion of the N-terminal 47 residues of CELD solubilized MUGase activity in E. coli. CELD exhibited sequence similarity with beta-glucosidase B of Clostridium thermocellum, particularly in the vicinity of the active-site aspartate residue, but did not display structural similarity with the mature forms of cellulases and xylanases expressed by P. fluorescens subsp. cellulosa.


Sign in / Sign up

Export Citation Format

Share Document