Mapping the mammalian ribosome quality control complex interactome using proximity labeling approaches.

Previous genetic and biochemical studies from Saccharomyces cerevisiae have identified a critical ribosome-associated quality control complex (RQC) that facilitates resolution of stalled ribosomal complexes. While components of the mammalian RQC have been examined in vitro, a systematic characterization of RQC protein interactions in mammalian cells has yet to be described. Here we utilize both proximity-labeling proteomic approaches, BioID and APEX, and traditional affinity-based strategies to both identify interacting proteins of mammalian RQC members and putative substrates for the RQC resident E3 ligase, Ltn1. Surprisingly, validation studies revealed that a subset of substrates are ubiquitylated by Ltn1 in a regulatory manner that does not result in subsequent substrate degradation. We demonstrate that Ltn1 catalyzes the regulatory ubiquitylation of ribosomal protein S6 kinase 1 and 2 (RPS6KA1, RPS6KA3). Further, loss of Ltn1 function results in hyperactivation of RSK1/2 signaling without impacting RSK1/2 protein turnover. These results suggest that Ltn1-mediated RSK1/2 ubiquitylation is inhibitory and establishes a new role for Ltn1 in regulating mitogen-activated kinase signaling via regulatory RSK1/2 ubiquitylation. Taken together, our results suggest that mammalian RQC interactions are difficult to observe and may be more transient than the homologous complex in S. cerevisiae and that Ltn1 has RQC-independent functions

Site-specific identification and quantitation of endogenous SUMO modifications under native conditions.

Small ubiquitin-like modifier (SUMO) modification regulates numerous cellular processes. Unlike ubiquitin, detection of endogenous SUMOylated proteins is limited by the lack of naturally occurring protease sites in the C-terminal tail of SUMO proteins. Proteome-wide detection of SUMOylation sites on target proteins typically requires ectopic expression of mutant SUMOs with introduced tryptic sites. Here, we report a method for proteome-wide, site-level detection of endogenous SUMOylation that uses α-lytic protease, WaLP. WaLP digestion of SUMOylated proteins generates peptides containing SUMO-remnant diglycyl-lysine (KGG) at the site of SUMO modification. Using previously developed immuno-affinity isolation of KGG-containing peptides followed by mass spectrometry, we identified 1209 unique endogenous SUMO modification sites. We also demonstrate the impact of proteasome inhibition on ubiquitin and SUMO-modified proteomes using parallel quantitation of ubiquitylated and SUMOylated peptides. This methodological advancement enables determination of endogenous SUMOylated proteins under completely native conditions

An Improved Model for Dynamin Assembly Revealed by Cryo-EM

Continua com: Avaluació de la qualitat de l'aire a la ciutat de Barcelon

Structure of pectate lyase A: comparison to other isoforms

Pectate lyase A is a virulence factor secreted by the plant-pathogenic bacteria Erwinia chrysanthemi. The enzyme cleaves the glycosidic bond of pectate polymers by a calcium-dependent [beta]-elimination mechanism. The crystal structure of pectate lyase A from E. chrysanthemi EC16 has been determined in two crystal forms, monoclinic C2 to 1.8 Å and rhombohedral R3 to 2.1 Å. The protein structure is compared with two other pectate lyase isoforms from E. chrysanthemi EC16, pectate lyase C and pectate lyase E. Pectate lyase A is unique as it is the only acidic pectate lyase and has end products that are significantly more varied in length in comparison to those of the other four major pectate lyase isozymes. Differences and similarities in polypeptide trace, size and volume of the active-site groove and surface electrostatics are discussed

The Ursinus Weekly, May 16, 1974

Women\u27s hours abolished; Board votes rule change for next Fall • Show Boat and band Parent\u27s Day hits • Will rates go up? • Student writes play • Marsteller to publish constellation slides • New special students to take part in upcoming Summer School session • Yearbook trouble • The ghost of Ursinus past • Editorial: New rules = new responsibilities • Wanted: Fearless leader • Alumni Corner: What happens to Weekly editors? • Meistersingers tour • Art review • In praise of ProTheatre • The Zodiac: The Earth signs: Taurus, Virgo, Capricorn • Record review: Robin Trower: Bridge of Sighs • Seasons are near end • The Cinder scene wrap-uphttps://digitalcommons.ursinus.edu/weekly/1017/thumbnail.jp

The Ursinus Weekly, April 25, 1974

Jeane Dixon arrives at Ursinus College • Bruce Springsteen and band a big hit in Helfferich at first major rock music concert at Ursinus • Editorial staff named for Ursinus Weekly • Two more forums planned for April • IRC participates in Model UN • Committee meets on women’s hours • Editorial: Does anybody really care? • Jeane Dixon: Before it all happened • Union’s learn-ums: Mini-courses galore • Volunteers help special students • C. Vaughn Fitzgerald meets the challenge of London culture and energy crisis • Gutman speaks to Ec club • Freshman Mark Sellers new college chess champ • Travelin’ 7 benefits Pierce scholarship fund • The Zodiac: The water signs: Cancer, Scorpio, Pisces • Songfest slated for April 30 • Women’s Lacrosse hosts “all college” tri-outs • U.C. runs awayhttps://digitalcommons.ursinus.edu/weekly/1014/thumbnail.jp

Impaired tumor necrosis factor-α secretion by CD4 T cells during respiratory syncytial virus bronchiolitis associated with recurrent wheeze

BACKGROUND: Infants with severe respiratory syncytial virus (RSV) bronchiolitis have an increased risk of recurrent wheezing and asthma. We aimed to evaluate the relationships between regulatory T cell (Treg) percentage and cytokine production of in vitro-stimulated CD4+ T cells during acute bronchiolitis and the development of recurrent wheezing in the first 3 years of life. METHODS: We obtained peripheral blood from 166 infants hospitalized with their first episode of RSV-confirmed bronchiolitis. Granzyme B (GZB) expression, and interleukin-10, interferon-γ, tumor necrosis factor-α (TNF-α), IL-4, and IL-5 production by in vitro anti-CD3/CD28- and anti-CD3/CD46-activated CD4+ T cells, and percentage of peripheral Treg (CD4+CD25 RESULTS: Sixty-seven percent (n = 111) of children had wheezing after their initial RSV infection, with 30% having recurrent wheezing. The percentage of peripheral Treg (CD4+CD25 CONCLUSIONS: We demonstrated lower TNF-α production by in vitro stimulated CD4+ T cells during severe RSV bronchiolitis in children that subsequently developed recurrent wheezing, compared with children with no subsequent wheeze. These findings support the role of CD4+ T cell immunity in the development of subsequent wheezing in these children