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An oligod-d(T) 12-18 primed cDNA library has been prepared from Caldariomyces fumago mRNA. A clone containing a full-length insert was sequenced on the supercoiled plasmid, pBR322. The complete primary sequence of chloroperoxidase has been derived. We have also determined about 73% of the peptide sequence by amino acid sequencing. The DNA sequence data matches all of the available known peptide sequences. The mature polypeptide contains 300 amino acids having a combined molecular weight of 32,974 daltons. A putative signal peptide of 21 amino acids is proposed from DNA sequence data. The chloroperoxidase gene encodes three potential glycosylation sites recognized as Asn-X-Thr/Ser sequences. Three cysteine residues are found in the protein sequence. A small region around Cys87 bears a minimal homology to the active site of cytochrome P450cam. No other heme protein homologues can be detected. We propose that Cys87 serves as a thiolate ligand to the iron of heme prosthetic group. A rare arginine codon, AGG, is used three times out of twelve in contrast to the very infrequent use of this codon in E. coli or yeast.

The chloroperoxidase gene from the ifiamentous fungus Caldariomyces fumago has been isolated within a 16.3-kilobase insert in the vector XEMBL3. The DNA sequence of the gene and its immediate flanking regions has been determined, and the start site of transcription has been mapped by primer extension.Chloroperoxidase catalyzes the insertion of chlorine, bromine, and iodine atoms into organic acceptor molecules. It is intimately involved in the biosynthesis of chlorinated secondary metabolites in the filamentous fungus Caldariomyces fumago. The enzyme is glycosylated and secreted into the culture medium at levels of 500 mg/liter when fructose is used as the carbon source for growth. No enzyme is produced if glucose is used to provide carbon to the cells. Previous studies in our laboratory have shown that the chloroperoxidase mRNA pool varies in concert with the level of secreted enzyme activity (1).To determine the primary structure of chloroperoxidase and to begin to investigate what sequence elements of the chloroperoxidase gene control the expression and secretion of the protein, we have cloned and sequenced the gene and its flanking regions.Cloning the chloroperoxidase gene. Total cellular DNA from C. fumago was partially digested with the restriction endonuclease MboI. The resulting fragments were fractionated on a low-melting-point agarose gel, and the 15-to 22-kilobase (kb) fragments were eluted. The eluted fragments were ligated into the BamHI site of bacteriophage XEMBL3, and the recombinant phage were packaged in vitro using the Gigapak system from Stratagene Cloning Systems, San Diego, Calif. Fifty thousand recombinant phage were screened by plaque hybridization, using the insert from the cDNA clone pMA340 (1), labeled by nick translation, as the probe. Six positive clones were plaque purified by successive rounds of plaque hybridization. DNA isolated from each positive clone was digested with PvuII and subcloned into the SmaI site of M13mp8. Ninety-six subclones from each X clone were screened by colony hybridization using the oligonucleotide probe T7MC29 (1). Single-stranded DNA templates prepared from three appropriate subclones were sequenced, using the oligonucleotide T7MC29 as the primer in dideoxynucleotide chain termination reactions (14). The sequence of all three clones matched that of the cDNA clone pMA340, proving that they indeed included part of the structural gene for chloroperoxidase.Nucleotide sequence of the chloroperoxidase gene. To obtain the sequence of the entire structural gene and its * Corresponding author.

Due to rising living standards, it is important to improve wheat’s quality traits by adjusting its storage protein genes. The introduction or locus deletion of high molecular weight subunits could provide new options for improving wheat quality and food safety. In this study, digenic and trigenic wheat lines were identified, in which the 1Dx5+1Dy10 subunit, and NGli-D2 and Sec-1s genes were successfully polymerized to determine the role of gene pyramiding in wheat quality. In addition, the effects of ω-rye alkaloids during 1BL/1RS translocation on quality were eliminated by introducing and utilizing 1Dx5+1Dy10 subunits through gene pyramiding. Additionally, the content of alcohol-soluble proteins was reduced, the Glu/Gli ratio was increased and high-quality wheat lines were obtained. The sedimentation values and mixograph parameters of the gene pyramids under different genetic backgrounds were significantly increased. Among all the pyramids, the trigenic lines in Zhengmai 7698, which was the genetic background, had the highest sedimentation value. The mixograph parameters of the midline peak time (MPT), midline peak value (MPV), midline peak width (MPW), curve tail value (CTV), curve tail width (CTW), midline value at 8 min (MTxV), midline width at 8 min (MTxW) and midline integral at 8 min (MTxI) of the gene pyramids were markedly enhanced, especially in the trigenic lines. Therefore, the pyramiding processes of the 1Dx5+1Dy10, Sec-1S and NGli-D2 genes improved dough elasticity. The overall protein composition of the modified gene pyramids was better than that of the wild type. The Glu/Gli ratios of the type I digenic line and trigenic lines containing the NGli-D2 locus were higher than that of the type II digenic line without the NGli-D2 locus. The trigenic lines with Hengguan 35 as the genetic background had the highest Glu/Gli ratio among the specimens. The unextractable polymeric protein (UPP%) and Glu/Gli ratios of the type II digenic line and trigenic lines were significantly higher than those of the wild type. The UPP% of the type II digenic line was higher than that of the trigenic lines, while the Glu/Gli ratio was slightly lower than that of the trigenic lines. In addition, the celiac disease (CD) epitopes’ level of the gene pyramids significantly decreased. The strategy and information reported in this study could be very useful for improving wheat processing quality and reducing wheat CD epitopes.