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D Cullen

Publications and source records attributed to D Cullen.

At least 55 records · Page 3Linked to original sources
PubMed1992

Genomic organization of a cellulase gene family in Phanerochaete chrysosporium.

Southern blot and nucleotide sequence analysis of Phanerochaete chrysosporium BKM-F-1767 genomic clones indicate that this wood-degrading fungus contains at least six genes with significant homology to the Trichoderma reesei cellobiohydrolase I gene (cbh1). Using pulsed-field gel electrophoresis to separate P. chrysosporium chromosomes, the six cellulase genes were found to hybridize to at least three different chromosomes, one of which is dimorphic. The organization of these genes was similar in another P. chrysosporium strain, ME 446. It is clear that, unlike T. reesei, the most well-studied cellulolytic fungus, P. chrysosporium contains a complex, cbh1-like gene family.

Amino Acid Sequence↗
PubMed1992

Structure, organization, and transcription of a cellobiohydrolase gene cluster from Phanerochaete chrysosporium.

Restriction mapping and sequence analysis of cosmid clones revealed a cluster of three cellobiohydrolase genes in Phanerochaete chrysosporium. P. chrysosporium cbh1-1 and cbh1-2 are separated by only 750 bp and are located approximately 14 kb upstream from a cellulase gene previously cloned from P. chrysosporium (P. Sims, C. James, and P. Broda, Gene 74:411-422, 1988). Within a well-conserved region, the deduced amino acid sequences of P. chrysosporium cbh1-1 and cbh1-2 are, respectively, 80 and 69% homologous to that of the Trichoderma reesei cellobiohydrolase I gene. The conserved cellulose-binding domain typical of microbial cellulases is absent from cbh1-1. Transcript levels of the three P. chrysosporium genes varied substantially, depending on culture conditions. cbh1-1 and cbh1-2 were not induced in the presence of cellulose, nor did they appear to be subject to glucose repression. Therefore, aspects of the chromosomal organization, structure, and transcription of these genes are unlike those of any previously described cellulase genes.

Amino Acid Sequence↗
PubMed1992

Lignin peroxidase gene family of Phanerochaete chrysosporium: complex regulation by carbon and nitrogen limitation and identification of a second dimorphic chromosome.

Lignin peroxidases (LiP) of Phanerochaete chrysosporium are encoded by a family of six closely related genes. Five LiP genes have been localized to the same dimorphic chromosome. In this investigation, relative transcript levels of the LiP genes were determined. Transcripts of the LiPA, LiPB, and O282 genes were at similar levels in both carbon- and nitrogen-limited cultures. In contrast, transcription of the GLG5, V4, and GLG4 genes was dramatically altered by culture conditions. Under carbon-limited conditions, GLG4 transcripts were, by far, the most abundant. Southern blot analyses of clamped homogeneous field gels were used to map the GLG4 gene to a dimorphic chromosome separate from the other LiP genes.

Base Sequence↗
PubMed1991

Genomic organization of lignin peroxidase genes of Phanerochaete chrysosporium.

Three lignin peroxidase (LiP) genes from the basidiomycete Phanerochaete chrysosporium were cloned on a single 30 kb cosmid insert. One gene, GLG5, is the genomic equivalent of a previously reported cDNA clone, CLG5. The other two LiP genes are transcriptionally convergent and map to a position approximately 15 kb downstream of GLG5. The translational stop codons of these genes are separated by 1.3 kb. Analysis of homokaryons established allelic relationships to previously described LiP clones. Using clamped homogeneous electrical field electrophoresis (CHEF), seven chromosomal bands were resolved from P. chrysosporium genomic DNA. On CHEF gel Southern blots, the LiP gene family was localized to a single, dimorphic chromosome.

Base Sequence↗
PubMed1991

Genetic transformation of Aureobasidium pullulans.

Aureobasidium pullulans strain Y117 was transformed to hygromycin resistance using plasmid pDH33, which contains the bacterial hygromycin B phosphotransferase gene (hph) fused to promoter elements of the Aspergillus niger glucoamylase gene (glaA). Southern hybridizations of transformants revealed multiple, integrated copies of the vector. The glaA promoter was not induced by starch in A. pullulans as it is in A. niger; however, the transcriptional start points were the same in both species.

Aspergillus niger↗
PubMed1990

The promoter of the glucoamylase-encoding gene of Aspergillus niger functions in Ustilago maydis.

Promoter sequences from the Aspergillus niger glucoamylase-encoding gene (glaA) were linked to the bacterial hygromycin (Hy) phosphotransferase-encoding gene (hph) and this chimeric marker was used to select Hy-resistant (HyR) Ustilago maydis transformants. This is an example of an Ascomycete promoter functioning in a Basidiomycete. HyR transformants varied with respect to copy number of integrated vector, mitotic stability, and tolerance to Hy. Only 216 bp of glaA promoter sequence is required for expression in U. maydis but this promoter is not induced by starch as it is in Aspergillus spp. The transcriptional start points are the same in U. maydis and A. niger.

Aspergillus niger↗
PubMed1990

Leukocyte function-associated antigen 1 (LFA-1) is a signaling molecule for cytoskeletal changes in a human T cell line.

The HuT 78/2 clone is a human T cell clone which has an activated phenotype. When this line was stimulated with immobilized antibody to LFA-1, the majority of cells developed dendritic processes. These processes were demonstrated to contain cytoskeletal elements including microtubules and intermediate filaments. Phorbol myristate acetate synergized with and prolonged this effect. Thus, the LFA-1 molecule may function as a signaling molecule for cytoskeletal reorganization in a human T cell clone.

Antibodies, Monoclonal↗
PubMed1989

Molecular cloning and sequences of lignin peroxidase genes of Phanerochaete chrysosporium.

The genomic clones encoding lignin peroxidase isozyme H8 and two closely related genes were isolated from Phanerochaete chrysosporium BKM-1767, and their nucleotide sequences were determined. The positions and approximate lengths of introns were found to be highly conserved in all three clones. Analysis of homokaryotic derivatives indicated that the three clones are not alleles of the same gene(s).

Amino Acid Sequence↗
PubMed1987

Sequence and centromere proximal location of a transformation enhancing fragment ans1 from Aspergillus nidulans.

The Aspergillus nidulans sequence ans1, previously known to enhance transformation frequencies of pyr4-based vectors, was shown to enhance the efficiency of argB and trpC-based vectors. Increased efficiencies could be obtained by constructing vectors containing argB and ans1 or by cotransforming selectable plasmids (containing argB, trpC, or pyr4) with the non-selectable ans1 sequence. The preponderance of evidence suggests that the mechanism of ans1 activity does not involve homologous recombination events, in spite of the presence of multiple regions of homology in the A. nidulans genome. Genetic mapping localized ans1 to the vicinity of the centromere of linkage group I. The nucleotide sequence of a 1.8 Kb functional subclone of ans1 was determined and found to be highly A + T rich (81%).

Aspergillus nidulans↗
PubMed1987

Transformation of Aspergillus nidulans with the hygromycin-resistance gene, hph.

Aspergillus nidulans strain G191 was transformed to hygromycin resistance using plasmid pDH25, which contains the bacterial hygromycin B phosphotransferase gene (hph) fused to promoter elements of the A. nidulans trpC gene. Southern hybridizations of transformants revealed multiple, integrated copies of the vector. A pleiotropic effect conferring increased hygromycin B sensitivity was found to be associated with the A. nidulans pyrG89 allele. Plasmid pDH25 features a ClaI site immediately preceding the hph start codon thus permitting convenient replacement of the trpC sequences with other eukaryotic promoters.

Anti-Bacterial Agents↗
PubMed1986

Primary structure of Mucor miehei aspartyl protease: evidence for a zymogen intermediate.

The gene encoding the aspartyl protease of the filamentous fungus Mucor miehei has been cloned in Escherichia coli and the DNA sequenced. The deduced primary translation product contains an N-terminal region of 69 amino acid (aa) residues not present in the mature protein. By analogy to the evolutionarily related mammalian gastric aspartyl proteases it is inferred that the primary secreted product is a zymogen containing a 47-aa propeptide. This propeptide is presumably removed in the later steps of the secretion process or upon secretion into the medium. To study the effects of modifications of the protease structure on its maturation by enzyme-engineering methods, an efficient expression system was sought. In E. coli, transcription of the preproenzyme coding sequence from a bacterial promoter results primarily in the accumulation of unsecreted, enzymatically inactive polypeptides, immunologically related to the authentic protease. In Aspergillus nidulans expression of the cloned gene, probably from its own promoter, results in the secretion into the culture medium of polypeptides which, compared to the authentic protease, are similar in specific activity, but differ in the character of their asparagine-linked oligosaccharides.

Amino Acid Sequence↗