Project description:ATP-binding cassette (ABC) transporters can translocate a broad spectrum of molecules across the cell membrane including physiological cargo and toxins. ABC transporters are known for the role they play in resistance towards anticancer agents in chemotherapy of cancer patients. There are 68 ABC transporters annotated in the genome of the social amoeba Dictyostelium discoideum. We have characterized more than half of these ABC transporters through a systematic study of mutations in their genes. We have analyzed morphological and transcriptional phenotypes for these mutants during growth and development and found that most of the mutants exhibited rather subtle phenotypes. A few of the genes may share physiological functions, as reflected in their transcriptional phenotypes. Since most of the abc-transporter mutants showed subtle morphological phenotypes, we utilized these transcriptional phenotypes to identify genes that are important for development by looking for transcripts whose abundance was unperturbed in most of the mutants. We found a set of 668 genes that includes many validated D. discoideum developmental genes. We have also found that abcG6 and abcG18 may have potential roles in intercellular signaling during terminal differentiation of spores and stalks.
Project description:ATP-binding cassette (ABC) transporters can translocate a broad spectrum of molecules across the cell membrane including physiological cargo and toxins. ABC transporters are known for the role they play in resistance towards anticancer agents in chemotherapy of cancer patients. There are 68 ABC transporters annotated in the genome of the social amoeba Dictyostelium discoideum. We have characterized more than half of these ABC transporters through a systematic study of mutations in their genes. We have analyzed morphological and transcriptional phenotypes for these mutants during growth and development and found that most of the mutants exhibited rather subtle phenotypes. A few of the genes may share physiological functions, as reflected in their transcriptional phenotypes. Since most of the abc-transporter mutants showed subtle morphological phenotypes, we utilized these transcriptional phenotypes to identify genes that are important for development by looking for transcripts whose abundance was unperturbed in most of the mutants. We found a set of 668 genes that includes many validated D. discoideum developmental genes. We have also found that abcG6 and abcG18 may have potential roles in intercellular signaling during terminal differentiation of spores and stalks. Transcriptional phenotyping during development of abc transporter mutants in Dictyostelium discoideum
Project description:We identified 3418 genes transcribed at a level of at least two copies each. We identified many transcripts involved in protein translation, cell maintenance and metabolism, as expected for vegetative cells. The most highly expressed cell signaling genes include ubiquitin, smlA, and nucleotide exchange factors RasGEF F and Ras GEF G. Additionally, we identified many genes previously reported to be expressed only during later stages of development including dutA, actin8, thioredoxin3, culmination specific protein 45D, discoidin II and yelA.
Project description:There is a paucity of data regarding what proteins localize to the mitochondria in the social amoeba Dictyostelium discoideum. Therefore, here, we utilized high-throughput tandem mass tag (TMT)-based protein quantitation to identify proteins in the whole-cell lysate, as well as in crude and purified mitochondrial samples. We then calculated the ratio of a protein’s abundance in the mitochondria isolates, both crude and highly purified, versus its abundance in the whole-cell lysate. The resulting value, indicating its enrichment in mitochondrial preparations, was further normalized to the average enrichment ratio of 47 reference mitochondrial proteins, to compute the relative enrichment ratio. Using this approach, we identified 908 putative mitochondrial proteins. We ultimately combined proteomic and in silico analyses to yield a comprehensive mitochondrial protein compendium. Our compendium lays the foundation for future studies to understand the functions of conserved mitochondrial proteins in health and diseases using D. discoideum as the model. It also provides an entry to study many fascinating mitochondrial processes that are unique in protists. Additionally, through comparative genomics, our compendium will complement mitochondrial protein discovery in other organisms and may shed light on the evolution of mitochondrial proteomes and processes.
Project description:Phytochromes are evolutionarily conserved photoreceptors in bacteria, fungi, and plants. The prototypical phytochrome comprises an N-terminal photosensory module and a C-terminal histidine kinase signaling-output module. However, the plant phytochrome has been postulated to transduce light signals by interacting with a group of nodal Phytochrome-Interacting transcription Factors (PIFs) and triggering their degradation via the N-terminal photosensory module, while its C-terminal output module, including a Histidine Kinase-Related Domain (HKRD), is thought not to participate directly in signaling. Here, we show that the C-terminal module of Arabidopsis phytochrome B (PHYB) is unexpectedly sufficient to mediate the degradation of PIF3 and to induce a distinct set of PIF-regulated photosynthetic genes. These signaling functions require the HKRD and particularly its dimerization. A D1040V mutation, which disrupts the dimerization of HKRD and the interaction between the C-terminal module and PIF3, abrogates the early light signaling functions of PHYB in nuclear accumulation, photobody biogenesis, and PIF3 degradation. In contrast, disruption of the interaction between PIF3 and PHYB’s N-terminal photosensory module has little effect on PIF3 degradation. Together, this study provides novel insight into the central mechanism of early phytochrome signaling that the C-terminal signaling-output module of PHYB interacts with PIF3 in the nucleus to mediate PIF3 degradation by light.
Project description:We describe the gene expression pattern of a Dictyostelium discoideum mutant depleted in the C-module-binding factor (CbfA) and autonomous gene-regulatory activities of CbfA carboxy-terminal domains (CbfA-CTDs)
Project description:We describe the gene expression pattern of a Dictyostelium discoideum mutant depleted in the C-module-binding factor (CbfA) and autonomous gene-regulatory activities of CbfA carboxy-terminal domains (CbfA-CTDs) Comparison of gene expression in growing cells of a CbfA mutant compared to wild-type