The products of the trithorax gene are required to stably maintain homeotic gene expression patterns established during embryo-genesis by the action of the transiently expressed segmentation genes. We have determined the intron/exon structure of the trx gene and the large alternatively spliced trx RNAs, which are capable of encoding only two protein isoforms. These very large trx proteins differ only in a long Ser- and Gly-rich N-terminal extension, encoded by exon II, which is present only in the larger trx isoform. We have identified a novel variant of the highly conserved nuclear receptor type of DNA binding domain. We have found that the previously identified Cys-rich central region contains multiple novel zinc finger motifs which are also present in the Polycomb-like protein and RBP2, a retinoblastoma binding protein. The trx proteins terminate with another novel conserved domain which we have identified in proteins from three kingdoms, including plants and fungi, indicating that has an ancient origin. Many of these proteins are chromosomally associated, suggesting that this domain may be involved in interactions between trx and other highly conserved components of chromatin involved in transcription regulation. The sequence alterations of trx mutations identify the highly conserved regions of trx as critical for the function of these large proteins. We show that zygotically expressed trx RNAs encoding the larger protein isoform are initially expressed in a spatially restricted pattern which overlaps the expression domains of the BX-C genes Ubx, abd-A and Abd-B. This pattern is transient and evolves into a broader expression domain encompassing the entire germ band during the extended germ band stage.

Regulation of intra-and extracellular ion activities

A new family of cyclophilins with an RNA recognition motif (RRM) has members in vertebrates, roundworms and flatworms. We have identified a Drosophilacyclophilin, Dcyp33, with a high degree of amino acid sequence identity and similarity with other members of the family. Dcyp33 interacts through its RRM domain with the third PHD finger of trithorax. This interaction is conserved in the human homologues of these proteins, Cyp33 and MLL. Over expression of Dcyp33 in DrosophilaSL1 cells results in down-regulation of AbdominalB Hoxgene expression, mirroring the effect of human Cyp33 on the expression of human HOXgenes.

bWith a completely reengineered and humanized glycosylation pathway, glycoengineered Pichia pastoris has emerged as a promising production host for the manufacture of therapeutic glycoproteins. However, the extensive genetic modifications have also negatively affected the overall fitness levels of the glycoengineered host cells. To make glycoengineered Pichia strains more compatible with a scalable industrial fermentation process, we sought to identify genetic solutions to broadly improve cell robustness during fermentation. In this study, we report that mutations within the Pichia pastoris ATT1 (PpATT1) gene (a homolog of the Saccharomyces cerevisiae GAL4 [ScGAL4] transcriptional activator) dramatically increased the cellular fitness levels of glycoengineered Pichia strains. We demonstrate that deletion of the PpATT1 gene enabled glycoengineered Pichia strains to improve their thermal tolerance levels, reduce their cell lysis defects, and greatly improve fermentation robustness. The extension of the duration of fermentation enabled the PpATT1-modified glycoengineered Pichia strains to increase their product yields significantly without any sacrifice in product quality. Because the ATT1 gene could be deleted from any Pichia strains, including empty hosts and protein-expressing production strains alike, we suggest that the findings described in this study are broadly applicable to any Pichia strains used for the production of therapeutic proteins, including monoclonal antibodies, Fc fusions, peptides, hormones, and growth factors. Since the approval of the first biopharmaceutical product (recombinant insulin) in 1982, biopharmaceuticals, as a prescription drug class, have enjoyed the highest growth rate within the pharmaceutical industry (1). With more than 230 approved products currently on the market, biopharmaceuticals are playing vital roles in the prevention and treatment of a wide variety of diseases, ranging across infectious diseases, inflammatory disorders, metabolic diseases, and cancer. Most biopharmaceuticals are manufactured from one of three different expression host systems: mammalian cells, yeasts, and bacteria (2). Bacterial systems (e.g., Escherichia coli) are the industry standard expression hosts for proteins that do not require posttranslational modifications (e.g., insulin, growth hormone, granulocyte colony-stimulating factor [G-CSF]). To date, mammalian cells (e.g., CHO) have been the preferred expression system for glycoproteins and monoclonal antibodies (MAbs), primarily due to their ability to produce glycosylation patterns adequate for drug safety and efficacy. Despite the advantages of being unicellular eukaryotes with efficient protein-folding and posttranslational-modification capabilities, yeasts are used for the production of only a small number of therapeutic proteins, because their high-mannose glycosylation patterns are not optimal for drug safety and efficacy.Glycoengineered Pichia pastoris has recently emerged as a promising production host for the manufacture of therapeutic ...