The Dictyostelium spore is surrounded by a 220 microm thick trilaminar coat that consists of inner and outer electron-dense layers surrounding a central region of cellulose microfibrils. In previous studies, a mutant strain (TL56) lacking three proteins associated with the outer layer exhibited increased permeability to macromolecular tracers, suggesting that this layer contributes to the coat permeability barrier. Electron microscopy now shows that the outer layer is incomplete in the coats of this mutant and consists of a residual regular array of punctate electron densities. The outer layer is also incomplete in a mutant lacking a cellulose-binding protein associated with the inner layer, and these coats are deficient in an outer-layer protein and another coat protein. To examine the mechanism by which this inner-layer protein, SP85, contributes to outer-layer formation, various domain fragments were overexpressed in forming spores. Most of these exert dominant negative effects similar to the deletion of outer-layer proteins, but one construct, consisting of a fusion of the N-terminal and Cys-rich C1 domain, induces a dense mat of novel filaments at the surface of the outer layer. Biochemical studies show that the C1 domain binds cellulose, and a combination of site-directed mutations that inhibits its cellulose-binding activity suppresses outer-layer filament induction. The results suggest that, in addition to a previously described early role in regulating cellulose synthesis, SP85 subsequently contributes a cross-bridging function between cellulose and other coat proteins to organize previously unrecognized structural elements in the outer layer of the coat.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1099/mic.0.25984-0 | DOI Listing |
Angew Chem Int Ed Engl
December 2024
Northeast Normal University, MOE Key Laboratory for UV Light-Emitting Materials and Technology, CHINA.
Zn-Mn aqueous batteries (ZMABs) are widely recognized as a promising candidate for large-scale energy storage due to their cost-effectiveness, high safety and environmental friendliness. However, the practical application of ZMABs is hindered by inherent electrical contact loss, hydrogen evolution and dendrite growth on traditional anodes. Here, a three-tiered golf anode with high conductivity is developed to simultaneously enhance the reversibility of Zn and Mn metals.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Fudan University, Department of Chemistry, Institute of Biomedical Sciences, Handan road, 200433, Shanghai, CHINA.
Electrochemiluminescence (ECL) microscopy has emerged as a powerful technique for single-cell imaging owing to its unparalleled background-free imaging advantages. However, controlled intracellular ECL imaging remains challenging. Here, we developed a stimuli-responsive self-assembled DNA nanomachine that enables the ECL imaging of intracellular target biomolecules in single cells.
View Article and Find Full Text PDFThe peptidoglycan (PG) cell wall is the primary protective layer of bacteria, making the process of PG synthesis a key antibiotic target. Class A penicillin-binding proteins (aPBPs) are a family of conserved and ubiquitous PG synthases that fortify and repair the PG matrix. In gram-negative bacteria, these enzymes are regulated by outer-membrane tethered lipoproteins.
View Article and Find Full Text PDFIUCrdata
October 2024
Chemistry Department, Bindura University of Science Education, Private Bag 1020, Bindura, Zimbabwe.
The mol-ecular structure of the title compound, CHNO reveals non-co-planarity between the central formamidine backbone and each of the outer meth-oxy- and -propyl- substituted benzene rings with dihedral angles of 7.88 (15) and 81.17 (15)°, respectively, indicating significant twists in the mol-ecule.
View Article and Find Full Text PDFJ Control Release
December 2024
School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China; State Key Laboratory of Anti-Infective Drug Discovery and Development, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China. Electronic address:
Therapeutic challenges of chronic pulmonary infections caused by multidrug-resistant Pseudomonas aeruginosa (MDRP. aeruginosa) biofilms due to significantly enhanced antibiotic resistance. This resistance is driven by reduced outer membrane permeability, biofilm barriers, and excessive secretion of virulence factors.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!