Showing papers by "Susan Lindquist published in 2005"

HSP90 and the chaperoning of cancer.

Abstract: Standing watch over the proteome, molecular chaperones are an ancient and evolutionarily conserved class of proteins that guide the normal folding, intracellular disposition and proteolytic turnover of many of the key regulators of cell growth, differentiation and survival. This essential guardian function is subverted during oncogenesis to allow malignant transformation and to facilitate rapid somatic evolution. Pharmacologically 'bribing' the essential guard duty of the chaperone HSP90 (heat-shock protein of 90 kDa) seems to offer a unique anticancer strategy of considerable promise.

Hsp90 potentiates the rapid evolution of new traits: drug resistance in diverse fungi.

Abstract: Hsp90 is a molecular chaperone for many signal transducers and may influence evolution by releasing previously silent genetic variation in response to environmental change. In fungi separated by ∼800 million years of evolution, Hsp90 potentiated the evolution of drug resistance in a different way, by enabling new mutations to have immediate phenotypic consequences. Resistance was abrogated by Hsp90 inhibitors and by febrile temperatures, suggesting new therapeutic strategies and a clinical benefit of fever. During selection in a human host, drug resistance that was initially Hsp90-dependent evolved toward independence. Thus, Hsp90 can act in diverse ways to couple environmental contingency to the emergence and fixation of new traits.

Prions as adaptive conduits of memory and inheritance

Abstract: Changes in protein conformation drive most biological processes, but none have seized the imagination of scientists and the public alike as have the self-replicating conformations of prions. Prions transmit lethal neurodegenerative diseases by means of the food chain. However, self-replicating protein conformations can also constitute molecular memories that transmit genetic information. Here, we showcase definitive evidence for the prion hypothesis and discuss examples in which prion-encoded heritable information has been harnessed during evolution to confer selective advantages. We then describe situations in which prion-enciphered events might have essential roles in long-term memory formation, transcriptional memory and genome-wide expression patterns.

Structural insights into a yeast prion illuminate nucleation and strain diversity

Abstract: Self-perpetuating changes in the conformations of amyloidogenic proteins play vital roles in normal biology and disease. Despite intense research, the architecture and conformational conversion of amyloids remain poorly understood. Amyloid conformers of Sup35 are the molecular embodiment of the yeast prion known as [PSI], which produces heritable changes in phenotype through self-perpetuating changes in protein folding. Here we determine the nature of Sup35's cooperatively folded amyloid core, and use this information to investigate central questions in prion biology. Specific segments of the amyloid core form intermolecular contacts in a 'Head-to-Head', 'Tail-to-Tail' fashion, but the 'Central Core' is sequestered through intramolecular contacts. The Head acquires productive interactions first, and these nucleate assembly. Variations in the length of the amyloid core and the nature of intermolecular interfaces form the structural basis of distinct prion 'strains', which produce variant phenotypes in vivo. These findings resolve several problems in yeast prion biology and have broad implications for other amyloids.

Increase in Activity During Calorie Restriction Requires Sirt1

Abstract: Sir2 (silent information regulator 2) is a nicotinamide adenine dinucleotide-dependent deacetylase required for longevity due to calorie restriction in yeast and Drosophila. In mammals, calorie restriction induces a complex pattern of physiological and behavioral changes. Here we report that the mammalian Sir2 ortholog, Sirt1, is required for the induction of a phenotype by calorie restriction in mice.

Harnessing Natural Diversity to Probe Metabolic Pathways

Abstract: Analyses of cellular processes in the yeast Saccharomyces cerevisiae rely primarily upon a small number of highly domesticated laboratory strains, leaving the extensive natural genetic diversity of the model organism largely unexplored and unexploited. We asked if this diversity could be used to enrich our understanding of basic biological processes. As a test case, we examined a simple trait: the utilization of di/tripeptides as nitrogen sources. The capacity to import small peptides is likely to be under opposing selective pressures (nutrient utilization versus toxin vulnerability) and may therefore be sculpted by diverse pathways and strategies. Hitherto, dipeptide utilization in S. cerevisiae was solely ascribed to the activity of a single protein, the Ptr2p transporter. Using high-throughput phenotyping and several genetically diverse strains, we identified previously unknown cellular activities that contribute to this trait. We find that the Dal5p allantoate/ureidosuccinate permease is also capable of facilitating di/tripeptide transport. Moreover, even in the absence of Dal5p and Ptr2p, an additional activity—almost certainly the periplasmic asparaginase II Asp3p—facilitates the utilization of dipeptides with C-terminal asparagine residues by a different strategy. Another, as-yet-unidentified activity enables the utilization of dipeptides with C-terminal arginine residues. The relative contributions of these activities to the utilization of di/tripeptides vary among the strains analyzed, as does the vulnerability of these strains to a toxic dipeptide. Only by sampling the genetic diversity of multiple strains were we able to uncover several previously unrecognized layers of complexity in this metabolic pathway. High-throughput phenotyping facilitates the rapid exploration of the molecular basis of biological complexity, allowing for future detailed investigation of the selective pressures that drive microbial evolution.

Navigating the ClpB channel to solution.

Abstract: New work places the Hsp70/DnaK system in an opening role in protein disaggregation, facilitating the extraction of individual polypeptides from the aggregate surface to the axial channel of Hsp104/ClpB. It also reinforces a long-standing belief that reactivation rather than simple clearance of aggregated protein is necessary for cell stress tolerance.

Compounds, compositions and methods of inhibiting alpha-synuclein toxicity

Abstract: Compounds and compositions are provided for treatment or amelioration of one or more symptoms of α-synuclein toxicity, α-synuclein mediated diseases or diseases in which α-synuclein fibrils are a symptom or cause of the disease. In one embodiment, the compounds for use in the compositions and methods are heteroaryl acylguanidines, heteroarylhydrazones, dihy-dropyridones, heteroaryl and aryl styryl ketones, and heteroarylpyrazoles.

Electrical conductors and devices from prion-like proteins

Abstract: The present invention provides novel polypeptides comprising a prion-aggregation domain and a second domain; novel polynucleotides encoding such polypeptides; host cells transformed or transfected with such polynucleotides; novel fibrils with specific functionalities and unusually high chemical and thermal stability; and methods of making and using the foregoing.

Compounds, compositions and methods of inhibiting a-synuclein toxicity

Abstract: Compounds and compositions are provided for treatment or amelioration of one or more symptoms of α-synuclein toxicity, α-synuclein mediated diseases or diseases in which α-synuclein fibrils are a symptom or cause of the disease. In one embodiment, the compounds for use in the compositions and methods are heteroaryl acylguanidines, heteroarylhydrazones, dihydropyridones, heteroaryl and aryl styryl ketones, and heteroarylpyrazoles.

Compositions and methods for treatment of protein misfolding diseases

Abstract: Disclosed are compounds and conditions that either suppress or enhance toxicity in yeast cells expressing alpha synuclein or huntingtin. These compounds and conditions can be used in the development of compositions that suppress toxicity, fibril formation, and/or diseases mediated at least in part by alpha synuclein or huntingtin.

Hsp90, buffering and drug resistance

Abstract: A method of reducing antifungal drug resistance in which Hsp inhibitors, such as Hsp90 inhibitors, are used.

Daph analogs and inhibition of protein aggregation

Abstract: The invention relates to compounds which inhibit aggregation of proteins of peptides, or disaggregate protein aggregates, and thereby antagonize the toxic effects of such aggregates. The invention also relates to methods for using such compounds and methods for discovering compounds that inhibit protein or peptide aggregation.