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Bacterial microcompartments are primitive organelles composed entirely of protein subunits. Genomic sequence databases reveal the widespread occurrence of microcompartments across diverse microbes. The prototypical bacterial microcompartment is the carboxysome, a protein shell for sequestering carbon fixation reactions. We report three-dimensional crystal(More)
The carboxysome is a bacterial microcompartment that functions as a simple organelle by sequestering enzymes involved in carbon fixation. The carboxysome shell is roughly 800 to 1400 angstroms in diameter and is assembled from several thousand protein subunits. Previous studies have revealed the three-dimensional structures of hexameric carboxysome shell(More)
We have determined the crystal structure of an active, hexameric fragment of the gene 4 helicase from bacteriophage T7. The structure reveals how subunit contacts stabilize the hexamer. Deviation from expected six-fold symmetry of the hexamer indicates that the structure is of an intermediate on the catalytic pathway. The structural consequences of the(More)
Helicases that unwind DNA at the replication fork are ring-shaped oligomeric enzymes that move along one strand of a DNA duplex and catalyze the displacement of the complementary strand in a reaction that is coupled to nucleotide hydrolysis. The helicase domain of the replicative helicase-primase protein from bacteriophage T7 crystallized as a helical(More)
Nature uses a limited set of metabolites to perform all of the biochemical reactions. To increase the metabolic capabilities of biological systems, we have expanded the natural metabolic network, using a nonnatural metabolic engineering approach. The branched-chain amino acid pathways are extended to produce abiotic longer chain keto acids and alcohols by(More)
The carboxysome is a bacterial organelle that functions to enhance the efficiency of CO2 fixation by encapsulating the enzymes ribulose bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase. The outer shell of the carboxysome is reminiscent of a viral capsid, being constructed from many copies of a few small proteins. Here we describe the(More)
Amyloid fibrils formed from different proteins, each associated with a particular disease, contain a common cross-beta spine. The atomic architecture of a spine, from the fibril-forming segment GNNQQNY of the yeast prion protein Sup35, was recently revealed by X-ray microcrystallography. It is a pair of beta-sheets, with the facing side chains of the two(More)
The developing science called structural genomics has focused to date mainly on high-throughput expression of individual proteins, followed by their purification and structure determination. In contrast, the term structural biology is used to denote the determination of structures, often complexes of several macromolecules, that illuminate aspects of(More)
Numerous soluble proteins convert to insoluble amyloid-like fibrils that have common properties. Amyloid fibrils are associated with fatal diseases such as Alzheimer's, and amyloid-like fibrils can be formed in vitro. For the yeast protein Sup35, conversion to amyloid-like fibrils is associated with a transmissible infection akin to that caused by mammalian(More)
The postsynaptic density (PSD) is a complex assembly of proteins associated with the postsynaptic membrane that organizes neurotransmitter receptors, signaling pathways, and regulatory elements within a cytoskeletal matrix. Here we show that the sterile alpha motif domain of rat Shank3/ProSAP2, a master scaffolding protein located deep within the PSD, can(More)