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Liu, Yanli

Publications and source records attributed to Liu, Yanli.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

State-of-the-art of data collection, analytics, and future needs of transmission utilities worldwide to account for the continuous growth of sensing data

Nowadays, transmission system operators require higher degree of observability in real-time to gain situational awareness and improve the decision-making process to guarantee a safe and reliable operation. Digitalization of energy systems allows utilities to monitor the system dynamic performance in real-time at fast time scales. The use of such technologies has unlocked new opportunities to introduce new data driven algorithms for improving the stability assessment and control of the system. Motivated by these challenges, a group of experts have worked together to highlight and establish a baseline set of these common concerns, which can be used as motivation to propose innovative analytics and data-driven solutions. In this document, the results of a survey on 10 transmission system operators around the world are presented and it aims to understand the current practices of the participating companies, in terms of data acquisition, handling, storage, modelling and analytics. The overall objective of this document is to capture the actual needs from the interviewed utilities, thereby laying the groundwork for setting valid assumptions for the development of advanced algorithms in this field.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Structural and histone binding studies of the chromo barrel domain of TIP60

Tat-interactive protein 60 consists of an N-terminal chromo barrel domain (TIP60-CB) and a C-terminal acetyltransferase domain and acetylates histone and nonhistone proteins in diverse cellular processes. While TIP60-CB is thought to recognize histone tails, molecular details of this interaction remain unclear. In this work, we attempted a quantitative analysis of the interaction between the human TIP60-CB and histone peptides, but did not observe any detectable binding by either fluorescence polarization or isothermal titration calorimetry assays. We also determined the crystal structure of the TIP60-CB alone. Analysis of the apo-tructure reveals a putative peptide-binding site that might be occluded by the basic side chain of a residue in a unique β hairpin between the two N-terminal strands of the β barrel, leading to the inability of TIP60-CB to bind histones.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Timescale Separation of Positive and Negative Signaling Creates History-Dependent Responses to IgE Receptor Stimulation

The high-affinity receptor for IgE expressed on the surface of mast cells and basophils interacts with antigens, via bound IgE antibody, and triggers secretion of inflammatory mediators that contribute to allergic reactions. To understand how past inputs (memory) influence future inflammatory responses in mast cells, a microfluidic device was used to precisely control exposure of cells to alternating stimulatory and non-stimulatory inputs. We determined that the response to subsequent stimulation depends on the interval of signaling quiescence. For shorter intervals of signaling quiescence, the second response is blunted relative to the first response, whereas longer intervals of quiescence induce an enhanced second response. Through an iterative process of computational modeling and experimental tests, we found that these memory-like phenomena arise from a confluence of rapid, short-lived positive signals driven by the protein tyrosine kinase Syk; slow, long-lived negative signals driven by the lipid phosphatase Ship1; and slower degradation of Ship1 co-factors. This work advances our understanding of mast cell signaling and represents a generalizable approach for investigating the dynamics of signaling systems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Peptide recognition by heterochromatin protein 1 (HP1) chromoshadow domains revisited: Plasticity in the pseudosymmetric histone binding site of human HP1

Heterochromatin protein 1 (HP1), a highly conserved non-histone chromosomal protein in eukaryotes, plays important roles in the regulation of gene transcription. Each of the three human homologs of HP1 includes a chromoshadow domain (CSD). The CSD interacts with various proteins bearing the PXVXL motif but also with a region of histone H3 that bears the similar PXXVXL motif. The latter interaction has not yet been resolved in atomic detail. Here we demonstrate that the CSDs of all three human HP1 homologs have comparable affinities to the PXXVXL motif of histone H3. The HP1 C-terminal extension enhances the affinity, as does the increasing length of the H3 peptide. The crystal structure of the human HP1γ CSD (CSDγ) in complex with an H3 peptide suggests that recognition of H3 by CSDγ to some extent resembles CSD-PXVXL interaction. Nevertheless, the prolyl residue of the PXXVXL motif appears to play a role distinct from that of Pro in the known HP1β CSD-PXVXL complexes. Lastly, we consequently generalize the historical CSD-PXVXL interaction model and expand the search scope for additional CSD binding partners.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Family-wide Characterization of Histone Binding Abilities of Human CW Domain-containing Proteins

Covalent modifications of histone N-terminal tails play a critical role in regulating chromatin structure and controlling gene expression. These modifications are controlled by histone-modifying enzymes and read out by histone-binding proteins. Numerous proteins have been identified as histone modification readers. Here we report the family-wide characterization of histone binding abilities of human CW domain-containing proteins. We demonstrate that the CW domains in ZCWPW2 and MORC3/4 selectively recognize histone H3 trimethylated at Lys-4, similar to ZCWPW1 reported previously, while the MORC1/2 and LSD2 lack histone H3 Lys-4 binding ability. Our crystal structures of the CW domains of ZCWPW2 and MORC3 in complex with the histone H3 trimethylated at Lys-4 peptide reveal the molecular basis of this interaction. In each complex, two tryptophan residues in the CW domain form the “floor” and “right wall,” respectively, of the methyllysine recognition cage. Our mutation results based on ZCWPW2 reveal that the right wall tryptophan residue is essential for binding, and the floor tryptophan residue enhances binding affinity. Here, our structural and mutational analysis highlights the conserved roles of the cage residues of CW domain across the histone methyllysine binders but also suggests why some CW domains lack histone binding ability.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Single-Cell Measurements of IgE-Mediated FcεRI Signaling Using an Integrated Microfluidic Platform

Heterogeneity in responses of cells to a stimulus, such as a pathogen or allergen, can potentially play an important role in deciding the fate of the responding cell population and the overall systemic response. Measuring heterogeneous responses requires tools capable of interrogating individual cells. Cell signaling studies commonly do not have single-cell resolution because of the limitations of techniques used such as Westerns, ELISAs, mass spectrometry, and DNA microarrays. Microfluidics devices are increasingly being used to overcome these limitations. In this paper, we report on a microfluidic platform for cell signaling analysis that combines two orthogonal single-cell measurement technologies: on-chip flow cytometry and optical imaging. The device seamlessly integrates cell culture, stimulation, and preparation with downstream measurements permitting hands-free, automated analysis to minimize experimental variability. The platform was used to interrogate IgE receptor (FcεRI) signaling, which is responsible for triggering allergic reactions, in RBL-2H3 cells. Following on-chip crosslinking of IgE-FcεRI complexes by multivalent antigen, we monitored signaling events including protein phosphorylation, calcium mobilization and the release of inflammatory mediators. The results demonstrate the ability of our platform to produce quantitative measurements on a cell-by-cell basis from just a few hundred cells. Finally, model-based analysis of the Syk phosphorylation data suggests that heterogeneity in Syk phosphorylation can be attributed to protein copy number variations, with the level of Syk phosphorylation being particularly sensitive to the copy number of Lyn.

59 BASIC BIOLOGICAL SCIENCES↗