Sifting texts: What can a digital tool tell us about late imperial literacy?

Presentation planned for cancelled AAS Conference 2020 suggests some possible future research that others might care to do using the Late Imperial Primer Literacy Sieve

Factors affecting outcome of treatment of clients who have requested marital counseling

Thesis (M.S.)--Boston Universit

Anchoring of Surface Proteins to the Cell Wall of Staphylococcus aureus: sortase catalyzed in vitro transpeptidation reaction using LPXTG peptide and NH2-Gly3 substrates

Staphylococcus aureus sortase anchors surface proteins to the cell wall envelope by cleaving polypeptides at the LPXTG motif. Surface proteins are linked to the peptidoglycan by an amide bond between the C-terminal carboxyl and the amino group of the pentaglycine cross-bridge. We find that purified recombinant sortase hydrolyzed peptides bearing an LPXTG motif at the peptide bond between threonine and glycine. In the presence of NH2-Gly3, sortase catalyzed exclusively a transpeptidation reaction, linking the carboxyl group of threonine to the amino group of NH2-Gly3. In the presence of amino group donors the rate of sortase mediated cleavage at the LPXTG motif was increased. Hydrolysis and transpeptidation required the sulfhydryl of cysteine 184, suggesting that sortase catalyzed the transpeptidation reaction of surface protein anchoring via the formation of a thioester acyl-enzyme intermediate

Anchoring of Surface Proteins to the Cell Wall of Staphylococcus aureus. III. Lipid II is an in vivo peptidoglycan substrate for sortase-catalyzed surface protein anchoring

Surface proteins of Staphylococcus aureus are anchored to the cell wall peptidoglycan by a mechanism requiring a C-terminal sorting signal with an LPXTG motif. Surface proteins are first synthesized in the bacterial cytoplasm and then transported across the cytoplasmic membrane. Cleavage of the N-terminal signal peptide of the cytoplasmic surface protein P1 precursor generates the extracellular P2 species, which is the substrate for the cell wall anchoring reaction. Sortase, a membrane-anchored transpeptidase, cleaves P2 between the threonine (T) and the glycine (G) of the LPXTG motif and catalyzes the formation of an amide bond between the carboxyl group of threonine and the amino group of cell wall cross-bridges. We have used metabolic labeling of staphylococcal cultures with [32P]phosphoric acid to reveal a P3 intermediate. The 32P-label of immunoprecipitated surface protein is removed by treatment with lysostaphin, a glycyl-glycine endopeptidase that separates the cell wall anchor structure. Furthermore, the appearance of P3 is prevented in the absence of sortase or by the inhibition of cell wall synthesis. 32P-Labeled cell wall anchor species bind to nisin, an antibiotic that is known to form a complex with lipid II. Thus, it appears that the P3 intermediate represents surface protein linked to the lipid II peptidoglycan precursor. The data support a model whereby lipid II-linked polypeptides are incorporated into the growing peptidoglycan via the transpeptidation and transglycosylation reactions of cell wall synthesis, generating mature cell wall-linked surface protein

Structures of Sortase B from Staphylococcus aureus and Bacillus anthracis Reveal Catalytic Amino Acid Triad in the Active Site

Surface proteins attached by sortases to the cell wall envelope of bacterial pathogens play important roles during infection. Sorting and attachment of these proteins is directed by C-terminal signals. Sortase B of S. aureus recognizes a motif NPQTN, cleaves the polypeptide after the Thr residue, and attaches the protein to pentaglycine cross-bridges. Sortase B of B. anthracis is thought to recognize the NPKTG motif, and attaches surface proteins to m-diaminopimelic acid cross-bridges. We have determined crystal structure of sortase B from B. anthracis and S. aureus at 1.6 and 2.0 Å resolutions, respectively. These structures show a β-barrel fold with α-helical elements on its outside, a structure thus far exclusive to the sortase family. A putative active site located on the edge of the β-barrel is comprised of a Cys-His-Asp catalytic triad and presumably faces the bacterial cell surface. A putative binding site for the sorting signal is located nearby

The modest professor:Interpretive charity and interpretive humility in John Rawls's lectures on the history of political philosophy

Governmen

Bacillus anthracis Secretes Proteins That Mediate Heme Acquisition from Hemoglobin

Acquisition of iron is necessary for the replication of nearly all bacterial pathogens; however, iron of vertebrate hosts is mostly sequestered by heme and bound to hemoglobin within red blood cells. In Bacillus anthracis, the spore-forming agent of anthrax, the mechanisms of iron scavenging from hemoglobin are unknown. We report here that B. anthracis secretes IsdX1 and IsdX2, two NEAT domain proteins, to remove heme from hemoglobin, thereby retrieving iron for bacterial growth. Unlike other Gram-positive bacteria, which rely on cell wall anchored Isd proteins for heme scavenging, B. anthracis seems to have also evolved NEAT domain proteins in the extracellular milieu and in the bacterial envelope to provide for the passage of heme