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Amino acid variants at the P94 position in Staphylococcus aureus class A sortase modulate substrate binding and enzyme activity

The surface of gram-positive bacteria is a highly regulated environment with specific attachment of proteins required for viability. Sortase enzymes are cysteine transpeptidases that recognize and ligate substrates to the peptidoglycan layer in these microorganisms, which can be highly pathogenic (e.g., Staphylococcus aureus, Streptococcus pyogenes, etc.). As such, sortases represent a potentially novel target for antibiotic development. In addition, the catalytic activity of sortase enzymes ...

— Cox-Tigre, N., Stewart, M. E., Tucker, J., Walkenhauer, E. G., Wilce, C. S., Antos, J. M., Amacher, J. F. 2026-01-18 00:00:00

Structural characterization of a minimal KLC2/Nup358/BicD2 complex

Cellular transport processes along microtubules are often facilitated by multi-motor complexes, which are connected by adapter proteins and cargoes. The nuclear pore protein Nup358, for example, interacts with the dynein adapter Bicaudal D2 (BicD2), which in turn recruits minus-end directed dynein motors and plus-end directed kinesin-1 motors for a nuclear positioning pathway that is essential for brain development. How motor recruitment is regulated by interactions of BicD2 with Nup358 is no...

— Noell, C. R., Solmaz, S. R. 2026-01-18 00:00:00

Characterization of novel cytoplasmic roles for the N-terminal methyltransferase NRMT1

N-terminal methylation of proteins by the trimethylase NRMT1 plays important roles in oncogenesis, development, and aging. As N-terminal methylation has frequently been shown to regulate protein-DNA interactions, and many NRMT1 substrates are transcription factors or regulators of chromatin structure, previous research has focused on how transcriptional regulation by NRMT1 affects cell growth and differentiation. However, we have recently identified a new, cytoplasmic role for NRMT1, inhibiti...

— Tooley, J. G., Zhou, G., Obeidat, S., Arbel, A., Jones, C., Tedeschi, F., Schaner Tooley, C. 2026-01-18 00:00:00

MIC13-linked cristae disruption causes metabolic failure and early fibrotic remodelling in mitochondrial liver disease

Mitochondrial diseases are highly complex and heterogeneous, and nearly 20% of cases involve severe liver pathology. MIC13-mediated hepato-encephalopathy is a rare mitochondrial hepatopathy with profound liver dysfunction, yet the mechanism by which MIC13 deficiency leads to severe hepatic dysfunction remains poorly understood. Here, we describe an affected individual carrying a pathogenic MIC13 variant (c.260-2A > G) that results in severe multisystem disease, including hepatopathy. To inves...

— Becker, A., Eichmann, T. O., Mey, K. a., Vasiliev, V., Petzsch, P., Rossi, A., Distelmaier, F., Anand, R. 2026-01-18 00:00:00

Covalent Leader Peptide Probes Enable Proteome-Level Mapping of RiPP Enzymes beyond Biosynthetic Gene Clusters

Genome-based analyses have enabled widespread discovery and biosynthetic annotation of ribosomally synthesized and post-translationally modified peptides (RiPPs) pathways, yet often fail to capture all participating enzymes, particularly those encoded outside canonical biosynthetic gene clusters. In this study, leveraging the central role of leader peptides (LPs) in RiPP enzyme-substrate recognition, we developed a substrate-guided chemical-proteomic strategy using covalent LP probes to direc...

— Wang, L., Wang, B., Wang, Y., Zheng, Y., Xia, Y., Xie, X., Wang, C., Tian, T., Zhao, J., Pan, H., Wang, H. 2026-01-18 00:00:00

The E. coli clamp loader sharply bends DNA to load β-clamp onto small gaps

DNA sliding clamps are used by the replication machines of all organisms, from bacteria to human. These clamps do not self-assemble onto DNA but require a multiprotein ATPase clamp loader that recognizes a DNA 3'-recessed end to open and close sliding clamps onto it. We find here that the mechanism of clamp loading onto small ssDNA gaps is profoundly different between bacteria and eukaryotes. The eukaryotic RFC clamp loader unwinds dsDNA from the 3'-recessed end to widen the ssDNA gap and als...

— Zheng, F., Yao, N. Y., Georgescu, R. E., Lyu, M., O'Donnell, M. E., Li, H. 2026-01-18 00:00:00

Localisation of corticosteroids in male mouse kidney by mass spectrometry imaging

Renal sodium balance is important for blood pressure homeostasis and is regulated by corticosteroids, chiefly aldosterone but also glucocorticoids. Abundance of these hormones in functional subregions of the kidney is unknown, previous work being limited to measurements in plasma and urine, and in microdialysate from kidney medulla. Here mass spectrometry imaging (MSI) was applied to map corticosteroids in kidney to understand how their distribution overlays with functional targets. Male C57B...

— Stasinopoulos, I., Khan, S., Melhem, S., Roumain, M., Cobice, D. F., Homer, N. Z. M., Mackay, C. L., Brown, R., Bailey, M. A., Andrew, R. 2026-01-17 00:00:00

Drying parameters and aging modulate protective properties of vitrified trehalose

Storage of biological materials is essential for medical, research, and biotechnological applications. While cold-chain preservation is effective, it is costly, infrastructure-dependent, and vulnerable to disruption. Room-temperature dry storage, inspired by desiccation-tolerant organisms, provides an alternative by stabilizing biomolecules in vitrified (glass-like) matrices that limit molecular motion which if not reduced can lead to breakdown and loss of integrity. Trehalose is widely used ...

— Kumara, U. G. V. S. S., Boothby, T. C. 2026-01-17 00:00:00

An Integrated Method for Profiling Lipid-Protein Interactions Using Multifunctional Lipid Probes

Cellular lipids shape health and disease through specific protein interactions, yet lipid-protein networks remain poorly defined. Despite rapid advances in functional lipid probes, the field still lacks a practical, dedicated protocol for conducting lipid-protein interaction studies. We describe detailed methods for determining lipid interactomes from cells using multifunctionalized lipid derivatives. We provide protocols that detail 1) how to treat cells with lipid derivatives and perform ph...

— Farley, S. E., Guzman, G., Blume, B., Stein, F., Schultz, C., Tafesse, F. G. 2026-01-17 00:00:00

Iterative Bump-and-hole engineering creates a bioorthogonal reporter for N-acetylglucosaminyltransferase I

Asparagine-linked protein glycosylation is among the most frequent modifications of proteins trafficking through the secretory pathway. These glycans are manufactured in an assembly line process to a common precursor that is then subject to individual modifications with different levels of complexity. An important biosynthetic modulator is the incorporation of N-acetylglucosamine (GlcNAc) at distinct positions in N-linked glycan biosynthesis, commencing with the activity of the glycosyltransf...

— Liu, Y., Pieters, S., Bineva-Todd, G., Sagiroglugil, M., Burnap, S. A., Hoddle, F., Cioce, A., Ohara, A., Bruemmer, K., Bertozzi, C., Polizzi, K. M., Struwe, W. B., Rovira, C., Schumann, B. 2026-01-17 00:00:00

Organic Components Modulate the Morphology of Respirable Aerovirology Relevant Aerosols

Airborne transmission of pathogens occurs via aerosol particles, whose morphology provides insights into the microenvironments that pathogens experience. Aerosol morphology includes particle size, shape, phase state, and chemical homogeneity, yet systematic studies remain limited. Here, we characterized model bioaerosol morphologies generated from (1) NaCl-organic two-component mixtures, (2) common cell culture media, and (3) artificial respiratory fluids. Particles were collected using a vir...

— Sapkota, D., Guo, Y., Chakraborty, A., Hu, J., Xie, H., Wu, I., Kim, M. J., Ouyang, H. 2026-01-17 00:00:00

Structure and mechanism of human sphingosine-1-phosphate transporter MFSD2B

Sphingosine-1-phosphate (S1P) is an essential signaling lipid that maintains vascular integrity and regulates immune cell trafficking. The major facilitator superfamily domain containing protein 2B (MFSD2B) serves as the main S1P exporter in red blood cells and platelets; however, its structure and transport mechanism are unclear. Here, we report the 3.0 A cryo-EM structure of human MFSD2B bound to S1P. S1P is captured in a distinctive binding state, deeply buried within the C- domain, with i...

— Ahmed, S., Huang, M., Dai, Y., Yang, X., Lee, C.-H., Nguyen, L. N. 2026-01-17 00:00:00

Discovery of a Human Metabolite that Mimics the Bacterial Quorum-Sensing Autoinducer AI-2

Bacteria use small molecules to orchestrate collective behaviors in a process called quorum sensing (QS), which relies on the production, release, and group-wide detection of extracellular signal molecules referred to as autoinducers. One QS autoinducer, termed AI-2, is broadly used for inter-species bacterial communication, including in the mammalian gut. AI-2 consists of a family of interconverting compounds and adducts originating from 4,5-hydroxy-2,3-pentanedione. This complex speciation,...

— Shine, E., Valastyan, J. S., Ying, V. Y., Huang, J. Z., Seyedsayamdost, M. R., Bassler, B. L. 2026-01-17 00:00:00

A Sustainable Approach to Natural Food Coloring: Alginate-Based Encapsulation and Stabilization of Beetroot Betalain

Betalains are natural, water-soluble pigments that are chiefly extracted from Beta vulgaris(beetroot) and have been widely researched as natural food colorants attributed to their natural coloring ability and antioxidant properties. On the other hand, their use is restricted by their poor stability response against exposure to natural elements like light, temperature fluctuations, oxygen, and changes in pH, which causes rapid decomposition of pigments and loss of coloration. The scope of this...

— ML, H., Murthy, A. N., Murthy, K. N., Y, C., B, D. T. C. 2026-01-16 00:00:00

Discovery of the Phosphonate Flavophos Produced by Burkholderia

Phosphonate natural products have proven value to society as antibiotics and herbicides, and inhibit a range of enzyme targets usually by mimicking the enzyme substrates. In this study, we investigate a family of phosphonate biosynthetic gene clusters (BGCs) found in Burkholderia. Heterologous expression in Escherichia coli resulted in production of an antimicrobial compound. Spectroscopic characterization and chemical synthesis assigned its structure as 2,4-dioxopentylphosphonic acid. One of...

— Simon, M. A., Ramos-Figueroa, J. S., Reyes Lopez, V., Ongpipattanakul, C., Zhu, L., Giurgiu, C., Hoffpauir, Z. A., Lamb, A. L., Nair, S. K., van der Donk, W. A. 2026-01-16 00:00:00

Illuminating spatial dynamics of glutamine metabolism with a sensitive genetically encoded biosensor

Glutamine is the most abundant amino acid in serum, used as a key nutrient by cells for protein synthesis, energy production, carbon and nitrogen metabolism, and cellular redox balance. The use of glutamine in the cell is highly compartmentalized, but the dynamics of glutamine metabolism across organelles and individual cells are not fully understood. To illuminate subcellular glutamine dynamics, we developed an intracellular glutamine optical reporter, iGlo. We find iGlo is sensitive and spe...

— Scully, J. M., Sun, M. J., Das, S., Arias, N. J., Kapelczak, E. D., Robinson, T. D., Vineall, K. G., Dean, T. S., TeSlaa, T., Divakaruni, A. S., Schmitt, D. L. 2026-01-16 00:00:00

Mechanistically Defined Epoxide- and Aziridine-2-carboxamide Electrophiles Enable Stereoselective Covalent RNA Modulation

RNA remains a largely untapped target for covalent small-molecule intervention due to the lack of electrophiles with predictable reactivity and stability in biological settings. Here, a mechanistically defined and tunable class of epoxide- and aziridine-2-carboxamide electrophiles that enable structure-guided covalent targeting of RNA is described. These warheads arise from an unexpected hydrolytic rearrangement of 3-chloropivalamide precursors under physiological conditions and selectively r...

— Li, C., Yang, X., Shan, J., Dickerson, K. A., Springer, N. A., Munshi, N. C., Batey, R. T., Disney, M. D. 2026-01-16 00:00:00

Reconstructing a Missing Link of HIV-1 Assembly: HIV-1 Envelope-Matrix Interactions in a Native Viral Context

The envelope surface glycoprotein (Env) on HIV-1 drives cell entry and genome delivery through its receptor binding and membrane fusion activities. Incorporation of Env onto assembling virions is governed by its cytoplasmic tail (Env-CT) and the matrix (MA) domain of the PR55Gag (Gag) polyprotein. To better understand how Gag recruits Env onto virions while reducing its antigenic profile by restricting Env copy number to low levels, we used cryo-electron tomography (cryo-ET) and subtomogram a...

— Croft, J. T., Do, H. N., Leaman, D. P., Lovendahl, K. N., Ralli-Jain, P., Chase, K. J., Derdeyn, C. A., Zwick, M. B., Gnanakaran, S., Lee, K. K. 2026-01-16 00:00:00

A comparative investigation of the mannose binding interface in DC-SIGN and MRC1 carbohydrate recognition domains with all-atom molecular dynamics simulations

Protein-carbohydrate interactions play a key role in numerous biological processes, including immune response, and glycan-based ligands that can target specific protein receptors on a cell surface represent promising candidates for therapeutics applications. For example, in retinoblastoma, the DC-SIGN mannose receptor (MR) is overexpressed on the surface of pathogenic cell and represents an interesting target for mannose-based ligands. At the same time, these ligands should not bind the MRC1 ...

— Geissler, S., Sacquin-Mora, S. 2026-01-16 00:00:00

Emergence of diverse ligase reactivities from a single RNA evolution experiment

RNA-catalyzed assembly of RNA strands was one of the most essential enzymatic functions in a primordial RNA-based biology. To explore the scope of RNA-catalyzed RNA assembly, we used directed evolution to re-engineer a ligase ribozyme that originally used 5'-phosphorimidazolide RNA substrates into a ribozyme that ligates RNA substrates carrying the biologically relevant 5'-triphosphate group. Unexpectedly, analysis of the low-abundance regime of the selected RNA population, representing ~0.1%...

— Biswas, A., DasGupta, S. 2026-01-16 00:00:00

Gβγ engages PLCβ3 at multiple sites to reorient and facilitate its activation

Phospholipase C {beta} (PLC{beta}) enzymes are activated by heterotrimeric G protein subunits, increasing hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2) at the plasma membrane. All four human PLC{beta} isoforms (PLC{beta}1-4) are activated by Gq, while PLC{beta}1-3 are activated to varying extents by G{beta}{gamma}. The binding sites for Gq on PLC{beta} are well-established and much has been learned about its mechanism of activation, but comparatively little is known about G{beta}...

— Fisher, I. J., Senarath, K., Outlaw, K., Muralidharan, K., Garland-Kuntz, E. E., Van Camp, M. M., Komay, T., Inoue, A., Kostenis, E., Lambert, N. A., Lyon, A. 2026-01-16 00:00:00

Structural Basis of Glycolytic Control in Trypanosoma cruzi: Insights from Enolase and PGI

Trypanosoma cruzi, the causative agent of Chagas disease, relies heavily on glycolysis for ATP production, making glycolytic enzymes attractive targets for therapeutic intervention. In this study, we report high-resolution crystal structures of two essential glycolytic enzymes, glucose-6-phosphate isomerase (Tc PGI; 1.8 A) and enolase (Tc enolase; 2.4 A), and integrate structural, biophysical, and computational analyses to evaluate their drug-target potential. Tc PGI adopts a dimeric alpha-be...

— Austin, K., Obakachi, V. A., Muzenda, F., Moetlediwa, M., Agyei, C., Nguyen, M., Tran, N., Edwards, T., Abendroth, J., Craig, T. K., Subramanian, S., Starker, B. L., Myler, P. J., Zininga, T., Govender, K. K., Chakafana, G. 2026-01-15 00:00:00

Substrate specificity in a designed RAS-targeting protease is coupled to active site and distal motions

Designing proteases with tailored substrate specificity has emerged as a powerful strategy for manipulating protein function in cells. RAS, a key regulator of cell survival and proliferation, is a compelling target for such approaches. Mutations in RAS are involved in about one-third of all human cancers and drive the hyperactive signaling that promotes tumorigenesis, growth, and metastasis in cancers such as pancreatic and lung cancer. This creates a pressing need for strategies capable of m...

— Chu, B., He, Y., Chen, Y., Toth, E. A., Orban, J. 2026-01-15 00:00:00

Mapping the GCK-GKRP interaction landscape using deep mutational scanning by reverse two-hybrid screening

Glucokinase (GCK) regulates insulin secretion in the pancreas and glycogen synthesis in the liver. The best characterized interaction partner of GCK is the glucokinase regulatory protein (GKRP). GKRP is expressed in the liver where it regulates GCK activity and abundance. In this study, we used a library of GCK single amino acid substitutions and a reverse two-hybrid screen to characterize the impact of GCK variants on GKRP interaction. We obtained interaction scores for 7534 GCK single amino...

— Gersing, S., Dahl, S. O., Lindorff-Larsen, K., Hartmann-Petersen, R. 2026-01-15 00:00:00

Novel Protoporphyrinogen oxidase 1 mutations endow resistance to PPO-inhibiting herbicides in Bassia scoparia

PPO-inhibiting herbicides are widely used to manage weeds in different cropping systems, yet resistance evolution threatens their long-term efficacy. Here, we investigated the molecular basis of resistance to PPO-inhibiting herbicides in Bassia scoparia biotypes collected from four locations in North Dakota, USA. Greenhouse dose-response assays revealed high levels of resistance to saflufenacil and carfentrazone-ethyl, while fomesafen retained full efficacy across all biotypes. Resistant plan...

— Porri, A., Geddes, C., Law, Q., Ikley, J., Willingham, S., Johnen, P., Meiners, I., Al-Sammarraie, S., Crommar, K., Ouwerkerk, P. B. F., Betz, M., Jenks, B. M., Heiser, H., Baumann, F., Braendle, F., Lerchl, J. 2026-01-15 00:00:00

Identification and inhibition of the Cyclin D Rb-docking interface that drives cell division

The animal cell division cycle is initiated by the cyclin-dependent kinases CDK4 and CDK6 in complex with D-type cyclins. Cyclin D-CDK4/6 complex formation is promoted by the assembly factors p21 and p27, which bind both subunits. p27 binds the hydrophobic patch on cyclin D that is similar to the patch used by other cell cycle cyclins to dock their substrates. This raised the question as to how cyclin D could find its substrates if its hydrophobic patch were already occupied? Here, we show th...

— Topacio, B. R., Fleming, C., Lanz, M., Zhang, S., Xie, S., Tuvikene, J., Weaver, A., Sanidas, I., Sage, J., Rubin, S., Koivomagi, M., Skotheim, J. 2026-01-15 00:00:00

Ancestors of Arylmalonate Decarboxylase show increased Activity, Stability and Stereoselectivity

Bacterial aryl malonate decarboxylase is a cofactor-free enzyme that generates a wide spectrum of -chiral carboxylic acids in outstanding optical purity, including several non-steroidal anti-inflammatory drugs and chiral building blocks. The well-characterized AMDase from Bordetella bronchiseptica (BbAMDase) and related enzymes of the same family have three main limitations: (i) low stability, both operational and thermal, and (ii) limited substrate spectrum regarding the size of the smaller ...

— van der Pol, E., Gerstenberger, J., Georgiadou, X., Schliep, K., Schuer, C., Kara, S., Kourist, R. 2026-01-14 00:00:00

Ubiquinone is a hysteretic modulator of the NADH:cytochrome b5 reductase activity of human Cb5R

BackgroundCytochrome b5 reductase is a flavoprotein that transfers electrons from NADH to multiple electron acceptors, such as cytochrome b5 or ubiquinone. Hysteresis is a phenomenon characterized by a slow transition between active and inactive catalytic states, leading to a lag phase in enzymatic activity. In this study, the effect of the soluble analogue of ubiquinone named 2,3 dimethoxy-5-methyl-1,4 benzoquinone (CoQ0) on the NADH:Cb5 reductase activity of recombinant human soluble Cb5R, ...

— Valerio, G. N., Martinez-Costa, O. H., Sanchez-Cabeza, C., Cordas, C. M., Samhan-Arias, A. K. 2026-01-14 00:00:00

Ketosis rescues frataxin deficiency and corrects disease phenotypes in an FRDA animal model

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by deficiency of the mitochondrial protein frataxin. Effective therapeutic options remain limited for FRDA. We previously demonstrated that frataxin regulates ketone body metabolism by modulating 3-Oxoacid CoA-Transferase 1 (OXCT1), the rate-limiting enzyme in ketone body catabolism. However, the mechanisms governing frataxin-dependent control of OXCT1 turnover as well as the contribution of frataxin deficienc...

— Dong, Y., Adeshina, M., Smith, R., Ngaba, L. V., An, J., Seline, O., Coulman, J., Ali, S. A. H., Mesaros, C., Xu, P., Lynch, D. R. 2026-01-14 00:00:00

Templating and confining calcium phosphate mineralization within designed protein assemblies

Bone formation involves the deposition of ordered hydroxyapatite (HAp) on collagen fibrils, but the underlying molecular mechanisms remain largely unresolved, limiting the design of protein-apatite hybrid materials. Here we show that computationally designed de novo proteins can template and confine HAp mineralization with molecular level precision. We design C3-symmetric oligomers with inner surfaces chemically complementary to the HAp {010} facet, and assemble these through additional inter...

— Yu, L. T., Pyles, H., Li, X., Borst, A. J., Bethel, N. P., Kwon, P. S., Weidle, C., Kibler, R. D., Carr, K. D., Liu, Y., Moroz, S., Zhang, S., DeYoreo, J. J., Baker, D. 2026-01-14 00:00:00