Biology subjects

Yu, L.-J.

Publications and source records attributed to Yu, L.-J..

4 recordsLinked to original sources

bioRxiv2025

In vivo Calcium Imaging in the Near-Infrared II Window

Non-invasive deep-tissue calcium imaging of live mammals with high sensitivity and resolution is challenging owing to light scattering experienced by traditional calcium ion (Ca2+) indicators with excitation and emission wavelengths within 400-750 nm. Here, we report near-infrared II (NIR-II) calcium imaging beyond 1000 nm by exploring a natural protein derived from a bacterium (Thermochromatium tepidum) living in a calcium carbonate-rich environment. This highly photostable fluorescent protein enables NIR-II imaging of intracellular Ca2+ responses to stimulant drugs in cultured mammalian cells with sensitivity comparable to that of visible Ca2+ indicators. We achieve in vivo NIR-II imaging of Ca2+ transients in response to two different tumor treatment strategies in intact tumors with high sensitivity, resolution, and contrast, opening the possibility of non-invasive deep-tissue calcium imaging for assessing treatment efficacy longitudinally. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/661443v2_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@149504eorg.highwire.dtl.DTLVardef@37722borg.highwire.dtl.DTLVardef@2878a7org.highwire.dtl.DTLVardef@1091d0c_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Ultrahigh Resolution Structure of the Heat-stable Form-IAq RuBisCO from the Thermophilic Purple Sulfur Bacterium Thermochromatium tepidum

Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzes the initial carbon fixation reaction in the Calvin-Benson-Bassham cycle in plants and most microbial autotrophs. Among the many forms of RuBisCOs, form-I--a protein complex containing 8 large and 8 small subunits--is the most common, representing over 90% of all known RuBisCOs. Although many form-I RuBisCO structures have been determined, no structure has been reported for a form-IAq RuBisCO. Here, and at ultrahigh (1.55 [A]) resolution, we detail the structure of the heat-stable form-IAq RuBisCO from the thermophilic and anaerobic purple bacterium Thermochromatium (Tch.) tepidum. The overall structure of the Tch. tepidum form-IAq RuBisCO resembles both a form-IAc RuBisCO from a chemolithotrophic sulfur bacterium and a synthetic form-I RuBisCO reconstructed from ancestral sequences. However, despite significant structural and sequence similarities with other form-I RuBisCOs, the Tch. tepidum form-IAq RuBisCO shows significantly greater interactions between adjacent small subunits through their extended N-terminal domains that contain a characteristic six-residue insertion unique to form-IAq RuBisCOs. Structural differences of Tch. tepidum RuBisCO from its mesophilic relative Allochromatium vinosum suggests the mechanisms of its enhanced thermostability. In addition to small subunit interactions, key substitutions on the hydrophilic surface of the small subunits likely contribute to its thermostability as well. It has been proposed that form-I RuBisCOs first appeared in anaerobic thermophiles. Our structure of the Tch. tepidum RuBisCO represents the first such structure of a form-IAq enzyme, providing fresh clues for unraveling the evolutionary history of RuBisCO and new details for how this key enzyme remains active at elevated temperatures.

plant biology↗

bioRxiv2024

Architecture of the spinach plastid-encoded RNA polymerase

The plastid-encoded RNA polymerase (PEP) serves as the principal transcription machinery within chloroplasts and is responsible for transcribing over 80% of primary plastid transcripts. Plant PEP is composed of a prokaryotic-like multisubunit core enzyme known as the PEP core, supplemented by newly evolved PEP-associated proteins (PAPs). In this study, we present the cryo-electron microscopy (cryo-EM) structure of a PEP complex derived from spinach (Spinacia oleracea). Our structural analysis unveils the presence of 14 PAPs closely associated with the PEP core complex consisting of 5 subunits, forming an irregular-shaped supercomplex. We provide a detailed depiction of the PEP core subunits and the 14 PAPs, elucidating their precise spatial arrangement and interactions. This research offers a crucial structural basis for future investigations into the functions and regulatory mechanisms governing plastid transcription.

biochemistry↗

bioRxiv2021

Asymmetric Structure of the Native Rhodobacter sphaeroides Dimeric LH1-RC Complex

The light-harvesting-reaction center (LH1-RC) core complex of purple photosynthetic bacterium Rhodobacter (Rba.) sphaeroides is characterized by the presence of both a dimeric form and a monomeric form. Following structure determination of the monomeric LH1-RC including its previously unrecognized component designated protein-U (Nat. Commun. 12, 6300, 2021), here we present cryo-EM structures of the dimeric LH1-RC from native Rba. sphaeroides IL106 at 2.75 [A] resolution and from an LH1-RC monomer lacking protein-U ({Delta}U) at 2.64 [A] resolution. The native dimeric core complex reveals many asymmetric features in the arrangement of its two monomeric components including the structural integrity of protein-U, the overall LH1 organization, and the rigidities of the proteins and pigments that form the complex. PufX polypeptides play a critical role in connecting two monomers, with one PufX interacting at its N-terminus with another PufX and an LH1 {beta}-polypeptide in another monomer, in good agreement with biochemical analyses. One of the proteins-U was only partially identified in the dimeric structure, signaling significantly different degrees of disorder in the two monomers. The {Delta}U LH1-RC monomer revealed a half-moon-shaped structure containing 11 - and 10 {beta}-polypeptides (compared with 14 of each in the wild type), indicating a critical role for protein-U in controlling the number of {beta}-subunits required for correct assembly and stabilization of the LH1-RC dimer. The structural features are discussed in relation to the unusual topology of intracytoplasmic photosynthetic membranes and an assembly model proposed for the native Rba. sphaeroides dimeric LH1-RC complex in membranes of wild-type cells.

biochemistry↗