Molecular details of a starch utilization pathway in the human gut symbiont Eubacterium rectale

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110609/1/mmi12859.pd

Structural basis of Toxoplasma gondii perforin-like protein 1 membrane interaction and activity during egress.

Intracellular pathogens must egress from the host cell to continue their infectious cycle. Apicomplexans are a phylum of intracellular protozoans that have evolved members of the membrane attack complex and perforin (MACPF) family of pore forming proteins to disrupt cellular membranes for traversing cells during tissue migration or egress from a replicative vacuole following intracellular reproduction. Previous work showed that the apicomplexan Toxoplasma gondii secretes a perforin-like protein (TgPLP1) that contains a C-terminal Domain (CTD) which is necessary for efficient parasite egress. However, the structural basis for CTD membrane binding and egress competency remained unknown. Here, we present evidence that TgPLP1 CTD prefers binding lipids that are abundant in the inner leaflet of the lipid bilayer. Additionally, solving the high-resolution crystal structure of the TgPLP1 APCβ domain within the CTD reveals an unusual double-layered β-prism fold that resembles only one other protein of known structure. Three direct repeat sequences comprise subdomains, with each constituting a wall of the β-prism fold. One subdomain features a protruding hydrophobic loop with an exposed tryptophan at its tip. Spectrophotometric measurements of intrinsic tryptophan fluorescence are consistent with insertion of the hydrophobic loop into a target membrane. Using CRISPR/Cas9 gene editing we show that parasite strains bearing mutations in the hydrophobic loop, including alanine substitution of the tip tryptophan, are equally deficient in egress as a strain lacking TgPLP1 altogether. Taken together our findings suggest a crucial role for the hydrophobic loop in anchoring TgPLP1 to the membrane to support its cytolytic activity and egress function

Galactomannan catabolism conferred by a polysaccharide utilisation locus of Bacteroides ovatus : enzyme synergy and crystal structure of a β-mannanase

A recently identified polysaccharide utilization locus (PUL) from Bacteroides ovatus ATCC 8483 is transcriptionally up-regulated during growth on galacto- and glucomannans. It encodes two glycoside hydrolase family 26 (GH26) β-mannanases, BoMan26A and BoMan26B, and a GH36 α-galactosidase, BoGal36A. The PUL also includes two glycan-binding proteins, confirmed by β-mannan affinity electrophoresis. When this PUL was deleted, B. ovatus was no longer able to grow on locust bean galactomannan. BoMan26A primarily formed mannobiose from mannan polysaccharides. BoMan26B had higher activity on galactomannan with a high degree of galactosyl substitution and was shown to be endo-acting generating a more diverse mixture of oligosaccharides, including mannobiose. Of the two β-mannanases, only BoMan26B hydrolyzed galactoglucomannan. A crystal structure of BoMan26A revealed a similar structure to the exo-mannobiohydrolase CjMan26C from Cellvibrio japonicus, with a conserved glycone region (-1 and -2 subsites), including a conserved loop closing the active site beyond subsite -2. Analysis of cellular location by immunolabeling and fluorescence microscopy suggests that BoMan26B is surface-exposed and associated with the outer membrane, although BoMan26A and BoGal36A are likely periplasmic. In light of the cellular location and the biochemical properties of the two characterized β-mannanases, we propose a schemeof sequential action by the glycoside hydrolasesencodedby the β-mannanPULandinvolved in the β-mannanutilization pathway in B. ovatus. The outer membrane-associated BoMan26B initially acts on the polysaccharide galactomannan, producing comparably large oligosaccharide fragments. Galactomanno-oligosaccharides are further processed in the periplasm, degalactosylated by BoGal36A, and subsequently hydrolyzed into mainly mannobiose by the β-mannanase BoMan26A

NANCY: Next-generation All-sky Near-infrared Community surveY

International audienceThe Nancy Grace Roman Space Telescope is capable of delivering an unprecedented all-sky, high-spatial resolution, multi-epoch infrared map to the astronomical community. This opportunity arises in the midst of numerous ground- and space-based surveys that will provide extensive spectroscopy and imaging together covering the entire sky (such as Rubin/LSST, Euclid, UNIONS, SPHEREx, DESI, SDSS-V, GALAH, 4MOST, WEAVE, MOONS, PFS, UVEX, NEO Surveyor, etc.). Roman can uniquely provide uniform high-spatial-resolution (~0.1 arcsec) imaging over the entire sky, vastly expanding the science reach and precision of all of these near-term and future surveys. This imaging will not only enhance other surveys, but also facilitate completely new science. By imaging the full sky over two epochs, Roman can measure the proper motions for stars across the entire Milky Way, probing 100 times fainter than Gaia out to the very edge of the Galaxy. Here, we propose NANCY: a completely public, all-sky survey that will create a high-value legacy dataset benefiting innumerable ongoing and forthcoming studies of the universe. NANCY is a pure expression of Roman's potential: it images the entire sky, at high spatial resolution, in a broad infrared bandpass that collects as many photons as possible. The majority of all ongoing astronomical surveys would benefit from incorporating observations of NANCY into their analyses, whether these surveys focus on nearby stars, the Milky Way, near-field cosmology, or the broader universe

NANCY: Next-generation All-sky Near-infrared Community surveY

International audienceThe Nancy Grace Roman Space Telescope is capable of delivering an unprecedented all-sky, high-spatial resolution, multi-epoch infrared map to the astronomical community. This opportunity arises in the midst of numerous ground- and space-based surveys that will provide extensive spectroscopy and imaging together covering the entire sky (such as Rubin/LSST, Euclid, UNIONS, SPHEREx, DESI, SDSS-V, GALAH, 4MOST, WEAVE, MOONS, PFS, UVEX, NEO Surveyor, etc.). Roman can uniquely provide uniform high-spatial-resolution (~0.1 arcsec) imaging over the entire sky, vastly expanding the science reach and precision of all of these near-term and future surveys. This imaging will not only enhance other surveys, but also facilitate completely new science. By imaging the full sky over two epochs, Roman can measure the proper motions for stars across the entire Milky Way, probing 100 times fainter than Gaia out to the very edge of the Galaxy. Here, we propose NANCY: a completely public, all-sky survey that will create a high-value legacy dataset benefiting innumerable ongoing and forthcoming studies of the universe. NANCY is a pure expression of Roman's potential: it images the entire sky, at high spatial resolution, in a broad infrared bandpass that collects as many photons as possible. The majority of all ongoing astronomical surveys would benefit from incorporating observations of NANCY into their analyses, whether these surveys focus on nearby stars, the Milky Way, near-field cosmology, or the broader universe

NANCY: Next-generation All-sky Near-infrared Community surveY

International audienceThe Nancy Grace Roman Space Telescope is capable of delivering an unprecedented all-sky, high-spatial resolution, multi-epoch infrared map to the astronomical community. This opportunity arises in the midst of numerous ground- and space-based surveys that will provide extensive spectroscopy and imaging together covering the entire sky (such as Rubin/LSST, Euclid, UNIONS, SPHEREx, DESI, SDSS-V, GALAH, 4MOST, WEAVE, MOONS, PFS, UVEX, NEO Surveyor, etc.). Roman can uniquely provide uniform high-spatial-resolution (~0.1 arcsec) imaging over the entire sky, vastly expanding the science reach and precision of all of these near-term and future surveys. This imaging will not only enhance other surveys, but also facilitate completely new science. By imaging the full sky over two epochs, Roman can measure the proper motions for stars across the entire Milky Way, probing 100 times fainter than Gaia out to the very edge of the Galaxy. Here, we propose NANCY: a completely public, all-sky survey that will create a high-value legacy dataset benefiting innumerable ongoing and forthcoming studies of the universe. NANCY is a pure expression of Roman's potential: it images the entire sky, at high spatial resolution, in a broad infrared bandpass that collects as many photons as possible. The majority of all ongoing astronomical surveys would benefit from incorporating observations of NANCY into their analyses, whether these surveys focus on nearby stars, the Milky Way, near-field cosmology, or the broader universe