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A large number of inhibitory receptors recruit SHP1 and/or SHP2, tandem-SH2-containing phosphatases through phosphotyrosine-based motifs immunoreceptor tyrosine-based inhibitory motif (ITIM) and immunoreceptor tyrosine-based switch motif (ITSM). Despite the similarity, these receptors exhibit differential effector binding specificities, as exemplified by the immune checkpoint receptors PD-1 and BTLA, which preferentially recruit SHP2 and SHP1, respectively. The molecular basis by which structurally similar receptors discriminate SHP1 and SHP2 is unclear. Here, we provide evidence that human PD-1 and BTLA optimally bind to SHP1 and SHP2 via a bivalent, parallel mode that involves both SH2 domains of SHP1 or SHP2. PD-1 mainly uses its ITSM to prefer SHP2 over SHP1 via their C-terminal SH2 domains (cSH2): swapping SHP1-cSH2 with SHP2-cSH2 enabled PD-1:SHP1 association in T cells. In contrast, BTLA primarily utilizes its ITIM to prefer SHP1 over SHP2 via their N-terminal SH2 domains (nSH2). The ITIM of PD-1, however, appeared to be de-emphasized due to a glycine at pY+1 position. Substitution of this glycine with alanine, a residue conserved in BTLA and several SHP1-recruiting receptors, was sufficient to induce PD-1:SHP1 interaction in T cells. Finally, structural simulation and mutagenesis screening showed that SHP1 recruitment activity exhibits a bell-shaped dependence on the molecular volume of the pY+1 residue of ITIM. Collectively, we provide a molecular interpretation of the SHP1/SHP2-binding specificities of PD-1 and BTLA, with implications for the mechanisms of a large family of therapeutically relevant receptors.

Tau protein misfolding and aggregation are pathological hallmarks of Alzheimer's disease and over twenty neurodegenerative disorders. However, the molecular mechanisms of tau aggregation in vivo remain incompletely understood. There are two types of tau aggregates in the brain: soluble aggregates (oligomers and protofibrils) and insoluble filaments (fibrils). Compared to filamentous aggregates, soluble aggregates are more toxic and exhibit prion-like transmission, providing seeds for templated misfolding. Curiously, in its native state, tau is a highly soluble, heat-stable protein that does not form fibrils by itself, not even when hyperphosphorylated. In vitro studies have found that negatively charged molecules such as heparin, RNA, or arachidonic acid are generally required to induce tau aggregation. Two recent breakthroughs have provided new insights into tau aggregation mechanisms. First, as an intrinsically disordered protein, tau is found to undergo liquid-liquid phase separation (LLPS) both in vitro and inside cells. Second, cryo-electron microscopy has revealed diverse fibrillar tau conformations associated with different neurodegenerative disorders. Nonetheless, only the fibrillar core is structurally resolved, and the remainder of the protein appears as a "fuzzy coat". From this review, it appears that further studies are required (1) to clarify the role of LLPS in tau aggregation; (2) to unveil the structural features of soluble tau aggregates; (3) to understand the involvement of fuzzy coat regions in oligomer and fibril formation. [ABSTRACT FROM AUTHOR]

Pyrazinamide ( PZA) is a first-line drug for tuberculosis ( TB) treatment and is responsible for shortening the duration of TB therapy. The mode of action of PZA remains elusive. RpsA, the ribosomal protein S1 of M ycobacterium tuberculosis ( M tb), was recently identified as a target of PZA based on its binding activity to pyrazinoic acid ( POA), the active form of PZA. POA binding to RpsA led to the inhibition of trans-translation. However, the nature of the RpsA- POA interaction remains unknown. Key questions include why POA exhibits an exquisite specificity to RpsA of M tb and how RpsA mutations confer PZA resistance. Here, we report the crystal structures of the C-terminal domain of RpsA of M tb and its complex with POA, as well as the corresponding domains of two RpsA variants that are associated with PZA resistance. Structural analysis reveals that POA binds to RpsA through hydrogen bonds and hydrophobic interactions, mediated mainly by residues ( Lys303, Phe307, Phe310 and Arg357) that are essential for tmRNA binding. Conformational changes induced by mutation or sequence variation at the C-terminus of RpsA abolish the POA binding activity. Our findings provide insights into the mode of action of PZA and molecular basis of PZA resistance associated with RpsA mutations. [ABSTRACT FROM AUTHOR]

The crystal structure of 3C proteinase (3Cpro) from Enterovirus 71 (EV71) was determined in space group C2221 to 2.2 Å resolution. The fold was similar to that of 3Cpro from other picornaviruses, but the difference in the β-ribbon reported in a previous structure was not observed. This β-ribbon was folded over the substrate-binding cleft and constituted part of the essential binding sites for interaction with the substrate. The structure of its complex with rupintrivir (AG7088), a peptidomimetic inhibitor, was also characterized in space group P212121 to 1.96 Å resolution. The inhibitor was accommodated without any spatial hindrance despite the more constricted binding site; this was confirmed by functional assays, in which the inhibitor showed comparable potency towards EV71 3Cpro and human rhinovirus 3Cpro, which is the target that rupintrivir was designed against. [ABSTRACT FROM AUTHOR]

Purpose/goals: The purpose of this poster presentation is to raise awareness about PICS for critical care nurses and the members of the interprofessional team in the ICU. Our goal is to propose a strengths approach to prevent and reduce the long-term risks of PICS to patients and their families following discharge. Outcome 1: Reflect upon their roles as advocates for PICS prevention and symptom management. Outcome 2: Identify possible interventions that could be implemented to decrease the impact of PICS on the patient's quality of life post discharge. Outcome 3: Provide an effective discharge plan for the patient and the family regarding PICS prevention and management. Session description: Advances in the critical care setting have reduced the rate of mortality among patients in the intensive care unit (ICU). Although more patients are recovering from their critical illness, success needs to be reflected in both ICU survival rates and optimal patient return to prehospital functional abilities (Makic, 2016). Post intensive care syndrome (PICS) is defined as a “new or worsening impairment in physical, cognitive, or mental health status arising after critical illness and persisting beyond discharge from the acute care setting” (Needham, 2012). PICS is identified as being both common and persistent after ICU discharge, with symptoms lasting from months to years. According to Rawal (2017), "the limited awareness about PICS among caregivers, may lead to a reduced quality of life, and cause significant suffering for patients and their families.” The purpose of this poster presentation is to raise awareness about PICS for critical care nurses and the members of the inter-professional team in the ICU. Our goal is to propose a strengths-based care approach to prevent and reduce the long-term risks of PICS to patients and their families following discharge. [ABSTRACT FROM AUTHOR]

Ca 2+ /calmodulin (CaM)-dependent kinase II (CaMKII) plays a critical role in long-term potentiation (LTP), a well-established model for learning and memory through the enhancement of synaptic transmission. Biochemical studies indicate that CaMKII catalyzes a phosphotransferase (kinase) reaction of both itself (autophosphorylation) and of multiple downstream target proteins. However, whether either type of phosphorylation plays any role in the synaptic enhancing action of CaMKII remains hotly contested. We have designed a series of experiments to define the minimal requirements for the synaptic enhancement by CaMKII. We find that autophosphorylation of T286 and further binding of CaMKII to the GluN2B subunit are required both for initiating LTP and for its maintenance (synaptic memory). Once bound to the NMDA receptor, the synaptic action of CaMKII occurs in the absence of target protein phosphorylation. Thus, autophosphorylation and binding to the GluN2B subunit are the only two requirements for CaMKII in synaptic memory., Competing Interests: Competing interests statement:The authors declare no competing interest.

Tau protein has important physiological functions at both presynaptic and postsynaptic terminals. Pathological tau species are also associated with synaptic dysfunctions in several neurodegenerative disorders, especially Alzheimer's disease. To understand tau distribution inside synaptic compartments, super-resolution imaging is required. Here, we describe a facile protocol to immobilize and image brain synaptosomes without aggregation artefacts, by substituting the standard fixative paraformaldehyde with ethylene glycol bis(succinimidyl succinate) (EGS). Super-resolution imaging of tau proteins is achieved through three-color direct stochastic optical reconstruction microscopy (dSTORM). Tau protein is found to colocalize with synaptic vesicles as well as postsynaptic densities., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)