Latest Publications
Mechanisms of permselectivity of connexin hemichannels to small molecules
Connexins can act either as hemichannels to facilitate ion and small-molecule movement from the cytosol to the extracellular space or as gap junction channels to provide a pathway for solute exchange between cells. Connexins are ubiquitously expressed throughout the body and are implicated in a wide range of processes. The permselectivity of connexin hemichannels for small neurochemicals remains poorly understood. By coexpressing genetically encoded fluorescent sensors for ATP, glutamate, and lactate with a range of connexins, we examined the ability of different hemichannels to permit the release of these compounds under physiological conditions and in response to physiological stimuli (small changes in partial pressure of CO2 and transmembrane depolarization). We found that some connexin hemichannels were relatively nonselective (Cx26, Cx32, Cx43, and Cx31.1) allowing passage of ATP, glutamate, and lactate. By contrast, other connexin hemichannels (Cx36, Cx46, and Cx50) were highly selective. Cx36 and Cx46 hemichannels allowed the release of ATP but not glutamate or lactate. The size of the permeating molecule cannot be the sole determinant of permselectivity. By contrast, Cx50 hemichannels permitted the release of lactate and glutamate but not ATP. We also found that the nature of the opening stimulus could alter the permselectivity of the hemichannel—for some of the relatively nonselective connexins, hemichannel opening via depolarization was ineffective at allowing the release of lactate. By performing a mutational analysis, informed by the differential selectivity of the closely related Cx46 and Cx50 hemichannels, we found that the charge on the N terminus and N terminus–transmembrane 2 interactions are key contributors to permselectivity for ATP.
Discovery of Late Intermediates in Methylenomycin Biosynthesis Active against Drug-Resistant Gram-Positive Bacterial Pathogens
Christophe Corre, Gideon A. Idowu, Lijiang Song, Melanie E. Whitehead, Lona M. Alkhalaf, Gregory L. Challis
The methylenomycins are highly functionalized cyclopentanone antibiotics produced by Streptomyces coelicolor A3(2). A biosynthetic pathway to the methylenomycins has been proposed based on sequence analysis of the proteins encoded by the methylenomycin biosynthetic gene cluster and the incorporation of labeled precursors. However, the roles played by putative biosynthetic enzymes remain experimentally uninvestigated. Here, the biosynthetic functions of enzymes encoded by mmyD, mmyO, mmyF, and mmyE were investigated by creating in-frame deletions in each gene and investigating the effect on methylenomycin production. No methylenomycin-related metabolites were produced by the mmyD mutant, consistent with the proposed role of MmyD in an early biosynthetic step. The production of methylenomycin A, but not methylenomycin C, was abolished in the mmyF and mmyO mutants, consistent with the corresponding enzymes catalyzing the epoxidation of methylenomycin C, as previously proposed. Expression of mmyF and mmyO in a S. coelicolor M145 derivative engineered to express mmr, which confers methylenomycin resistance, enabled the resulting strain to convert methylenomycin C to methylenomycin A, confirming this hypothesis. A novel metabolite (premethylenomycin C), which readily cyclizes to form the corresponding butanolide (premethylenomycin C lactone), accumulated in the mmyE mutant, indicating the corresponding enzyme is involved in introducing the exomethylene group into methylenomycin C. Remarkably, both premethylenomycin C and its lactone precursor were one to two orders of magnitude more active against various Gram-positive bacteria, including antibiotic-resistant Staphylococcus aureus and Enterococcus faecium isolates, than methylenomycins A and C, providing a promising starting point for the development of novel antibiotics to combat antimicrobial resistance.
Protein Target Highlights in CASP16: Insights From the Structure Providers
Leila T. Alexander, Océane M. Follonier, Andriy Kryshtafovych,| Kim Abesamis, Sabrina Bibi-Triki, Henry G. Box, Cécile Breyton, Françoise Bringel, Loic Carrique, Alessio d'Acapito, Gang Dong, Rebecca DuBois, Deborah Fass, JulianaMartinez Fiesco, Daniel R. Fox, Jonathan M. Grimes, Rhys Grinter, Matthew Jenkins, Roman Kamyshinsky, Jeremy R. Keown, Gerald Lackner, Michael Lammers, Shiheng Liu, Andrew L. Lovering,Tomas Malinauskas, Benoît Masquida, Gottfried J. Palm, Christian Siebold,Tiantian Su, Ping Zhang, Z. Hong Zhou, Krzysztof Fidelis, Maya Topf, John Moult, Torsten Schwed
This article presents an in-depth analysis of selected CASP16 targets, with a focus on their biological and functional significance. The authors highlight the most relevant features of the target proteins and discuss how well these were reproduced in the submitted predictions. While the overall performance of structure prediction methods remains impressive, challenges persist, particularly in modeling rare structural motifs, flexible regions, small molecule interactions, posttranslational modifications, and biologically important interfaces. Addressing these limitations can strengthen the role of structure prediction in complementing experimental efforts and advancing both basic research and biomedical applications.
Proteins (Structure, Function, Bioinformatics), October 2025
StayRose: A photostable StayGold derivative redshifted by genetic code expansion
Will Scott, Esther Ivorra-Molla, Dipayan Akhuli, Teresa Massam-Wu, Pawel K. Lysyganicz, Rylie Walsh, Matthew Parent, Jonathan Cook, Lijiang Song, Abhishek Kumar, Falk Schneider, Masanori Mishima, Allister Crow, Mohan K. Balasubramanian
Photobleaching of fluorescent proteins often limits the acquisition of high-quality images in microscopy. StayGold, a novel dimeric GFP recently monomerized through sequence engineering, addresses this challenge with its high photostability. There is now a focus on producing different colored StayGold derivatives to facilitate concurrent tagging of multiple targets. The unnatural amino acid 3-aminotyrosine has previously been shown to redshift superfolder GFP upon incorporation into its chromophore via genetic code expansion. Here, we apply the same strategy to redshift StayGold through substitution of tyrosine-58 with 3-aminotyrosine. The resultant red fluorescent protein, StayRose, shows an excitation wavelength maximum of 530 nm and an emission wavelength maximum of 588 nm. Importantly, the monomeric mStayRose retains the favorable photostability in vivo in Escherichia coli and zebrafish embryos. A high-resolution crystal structure of StayRose confirms the modified structure of the amino chromophore within an unperturbed 3D fold. Although reliant on genetic code expansion, StayRose provides an important step toward developing redshifted StayGold derivatives.
Better understanding complex pathomechanisms in central nervous system disorders as a prerequisite for improved diagnostic and therapeutic approaches
Piotr Walczak, Shen Li, Xumming Ji, Johannes Boltze
Central nervous system (CNS) disorders are usually characterized by a complex pathophysiology. The last issue of Neuroprotection featured reviews and research articles looking at peripheral factors such as the gut microbiome or a history of pre-eclampsia and their impact on CNS conditions. Articles presented in the current issue of Neuroprotection will shift the focus back to the CNS but will continue to provide insights from recent research that help to better understand the pathophysiological complexity of CNS conditions.
Neuroinflammation is known to be a hallmark and major contributor to many CNS diseases. It comprises both peripheral and central immune cells and can be modulated by frequent comorbidities such as hypertension. Moreover, neuroinflammatory processes can involve cell populations not primarily characterized as immune cells. Psychiatric conditions, including major depressive disorders (MDD), are increasingly recognized to be linked to neuroinflammation but also to systemic comorbidities, stress and aging. A better understanding of neuroinflammatory processes in the context of psychiatric conditions may help to identify novel therapeutic targets for better and potentially causal treatment strategies.
Development of biological soil crusts at the soil surface influences the persistence and movement of crop protection products
Laurence Hand, Mark C.J. Day, Carol Nichols, Hendrik Schäfer, Samantha Marshall, Gary D. Bending
Laboratory soil biodegradation studies required for approval of crop protection products (CPPs) are performed under continuous darkness, nullifying any potential contributions of algal and moss dominated biological soil crusts (BSC). There is growing evidence for metabolism of CPPs by phototrophic microorganisms under laboratory conditions, but limited data is available under field conditions. In this study we investigated the impact of the BSC on the fate of two 14C-fungicides under semi-field conditions using different light filters to alter formation of the BSC by exclusion/transmission of UV and photosynthetically active (PAR) wavelengths. Attenuation of PAR light significantly reduced formation of a BSC, which resulted in a significant slowing of the dissipation of benzovindiflupyr, which is known to be susceptible to phototrophic metabolism in aquatic systems, with 12–14 % more parent compound remaining at the end of the study when BSC development was impeded. For paclobutrazol, however, no significant difference in dissipation rate was observed. For both compounds there was significantly less non-extractable residue (NER) formation when BSC development was impeded (4–9 % reduction). Additionally, for both fungicides, the presence of a viable BSC resulted in 10–20 % more movement through the surface 5 mm of the soil, although this effect was limited to the period immediately after application and was likely due to increased porosity of the surface layer. This study confirms that the presence of phototrophs can significantly impact the environmental fate of CPPs on the surface of agricultural fields, either directly through metabolism or indirectly by altering the properties of the surface layer.