Biology subjects

Love, J.

Publications and source records attributed to Love, J..

3 recordsLinked to original sources

bioRxiv2018

Highly mutated memory cells drive an inefficient secondary antibody response to a variant protein

A powerful vaccine against mutable viruses might induce memory antibodies that either strongly bound antigenic variants or that could rapidly undergo secondary affinity maturation to achieve this. We have recently shown after secondary immunization of mice with a widely variant protein (Burton et al. 2018) that IgM+ memory B-cells with few mutations supported an efficient secondary germinal centre (GC) and serum response, superior to a primary response to the same protein. Here, boosting with more closely related proteins produced a GC response dominated by highly mutated B-cells that failed, not efficiently improving serum avidity even in the presence of extra adjuvant, and that was worse than a primary response. This supports a hypothesis that over certain antigenic differences, a cross reactive, mutated, memory B-cell compartment can be an impediment to affinity maturation.

immunology↗

bioRxiv2017

Ethylene signaling induces gelatinous layers with typical features of tension wood in hybrid aspen

Research conductedThe phytohormone ethylene impacts secondary stem growth in plants by stimulating cambial activity, xylem development and fiber over vessel formation. Here we report the effect of ethylene on secondary cell wall formation and the molecular connection between ethylene signaling and wood formation.\n\nMethodsWe applied exogenous ethylene or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) to wild type and ethylene insensitive hybrid aspen trees (Populus tremula x tremuloides) and studied secondary cell wall anatomy, chemistry and ultrastructure. We furthermore analyzed the transcriptome (RNA Seq) after ACC application to wild type and ethylene insensitive trees.\n\nKey resultsWe demonstrate that ACC and ethylene induce gelatinous-layers (G-layers) and alter the fiber cell wall cellulose microfibril angle. G-layers are tertiary wall layers rich in cellulose, typically found in tension wood of aspen trees. A vast majority of transcripts affected by ACC are downstream of ethylene perception and include a large number of transcription factors (TFs). Motif-analyses reveal potential connections between ethylene TFs (ERFs, EIN3/EIL1) and wood formation.\n\nConclusionG-layer formation upon ethylene application suggests that the increase in ethylene biosynthesis observed during tension wood formation is important for its formation. Ethylene-regulated TFs of the ERF and EIN3/EIL1 type could transmit the ethylene signal.

plant biology↗

bioRxiv2017

Structure-based analysis of CysZ-mediated cellular uptake of sulfate

Sulfur, most abundantly found in the environment as sulfate (SO42-), is an essential element in metabolites required by all living cells, including amino acids, co-factors and vitamins. Current understanding of the cellular delivery of SO42- at the molecular level is limited however. CysZ has been described as a SO42- permease, but its sequence family is without known structural precedent. Based on crystallographic structure information, SO42- binding and uptake experiments in cells and proteoliposomes, and single-channel conductance measurements, we provide insight into the molecular mechanism of CysZ-mediated translocation of SO42- across membranes. CysZ properties differ markedly from those of known transporters and ion channels. The structures display a hitherto unknown fold with dual topology, assembling in CysZ from Pseudomonas denitrificans as a trimer of antiparallel dimers in the membrane. CysZ structures from two other species recapitulate dimers from this assembly. Mutational studies highlight the functional relevance of conserved CysZ residues.

biophysics↗