Structure of cytosine transport protein CodB provides insight into nucleobase-cation symporter 1 mechanism
Caitlin E Hatton, Deborah H Brotherton, Mahalah Spencer, Alexander D Cameron
CodB is a cytosine transporter from the Nucleobase-Cation-Symport-1 (NCS1) transporter family, a member of the widespread LeuT superfamily. Here we solve the crystal structure of CodB from Proteus vulgaris, at 2.4 Å resolution in complex with cytosine. We show that CodB carries out the sodium-dependent uptake of cytosine and can bind 5-fluorocytosine. Comparison of the substrate-bound structures of CodB and the hydantoin transporter Mhp1, the only other NCS1 family member for which the structure is known, highlight the importance of the hydrogen bonds that the substrates make with the main chain at the breakpoint in the discontinuous helix, TM6. In contrast to other LeuT superfamily members, neither CodB nor Mhp1 makes specific interactions with residues on TM1. Comparison of the structures provides insight into the intricate mechanisms of how these proteins transport substrates across the plasma membrane.
John Clarkson publications
Identification of genetic loci in lettuce mediating quantitative resistance to fungal pathogens
Harry Pink, Adam Talbot, Abi Graceson, Juliane Graham, Gill Higgins, Andrew Taylor, Alison C Jackson, Maria Truco, Richard Michelmore, Chenyi Yao, Frances Gawthrop, David Pink, Paul Hand, John P Clarkson, Katherine Denby
With increasing prevalence of pathogen resistance to fungicides and environmental concerns, there is an urgent need to identify sources of genetic resistance to B. cinerea and S. sclerotiorum in lettuce. We demonstrated genetic variation for quantitative resistance to B. cinerea and S. sclerotiorum in a set of 97 diverse lettuce and wild relative accessions, and between the parents of lettuce mapping populations. Transcriptome profiling across multiple lettuce accessions enabled us to identify genes with expression correlated with resistance, predicting the importance of post-transcriptional gene regulation in the lettuce defence response. Differential gene expression analysis between the parent lines, and integration of data on correlation of gene expression and resistance in the diversity set, highlighted potential causal genes underlying the quantitative trait loci.
Preliminary Studies on Detection of Fusarium Basal Rot Infection in Onions and Shallots Using Electronic Nose
Malgorzata Labanska, Sarah van Amsterdam, Sascha Jenkins, John P Clarkson and James A Covington
Fusarium oxysporum f. sp. cepae, which causes fusarium basal rot disease, is considered one of the most harmful pathogens of onion and accounts for considerable crop losses annually. In this work, the capability of the PEN 3 electronic nose system to detect onion and shallot bulbs infected with F. oxysporum f. sp. cepae, to track the progression of fungal infection, and to discriminate between the varying proportions of infected onion bulbs was evaluated. To the best of our knowledge, this is a first report on successful application of an electronic nose to detect fungal infections in post-harvest onion and shallot bulbsThe electronic nose was proved to be a potentially useful tool for rapid, non-destructive monitoring of the post-harvest crops
Membrane lipid renovation in Pseudomonas aeruginosa - implications for phage therapy?
An important overlooked aspect is the impact of membrane lipid remodelling on phage binding ability. P. aeruginosa undergoes changes in membrane lipids when it encounters phosphorus stress, an environmental perturbation that is likely to occur during infection. Lipid changes include the substitution of glycerophospholipids with surrogate glycolipids and the over-production of ornithine-containing aminolipids. Given that membrane lipids are known to influence the structure and function of membrane proteins, we propose that changes in the composition of membrane lipids during infection may alter phage binding and subsequent phage infection dynamics. Consideration of such effects needs to be urgently prioritised in order to develop the most effective phage therapy strategies for P. aeruginosa infections.
Structural, Functional and Computational Studies of Membrane Recognition by Plasmodium Perforin-Like Proteins 1 and 2
Sophie I Williams, Xiulian Yu, Tao Ni, Robert JC Gilbert, Phillip J Stansfeld
Perforin-like proteins (PLPs) play key roles in mechanisms associated with parasitic disease caused by the apicomplexan parasites Plasmodium and Toxoplasma. Here we focus on Plasmodium vivax PLP1 and PLP2 (PvPLP1 and PvPLP2) compared to TgPLP1. Determination of the crystal structure of the membrane-binding APCβ domain of PvPLP1 reveals notable differences with TgPLP1, reflected in its inability to bind lipid bilayers as TgPLP1 and PvPLP2 do. This study underlines the substantial differences between the biophysical properties of the APCβ domains of apicomplexan PLPs, which reflect their significant sequence diversity. Such differences will be important factors in determining the cell targeting and membrane-binding activity of the different proteins in parasitic life cycles and disease.
Mode of action of a novel synthetic auxin herbicide, halauxifen-methyl
Jiaqi Xu, Xudong Liu, Richard Napier, Liyao Dong, Jun Li
Halauxifen-methyl is a new auxin herbicide developed by Corteva Agriscience (Wilmington, DE, USA). It has been suggested that ABF5 may be the target of halauxifen-methyl, as AFB5 mutants of Arabidopsis thaliana are resistant to halauxifen-methyl, which preferentially binds to AFB5. However, the mode of action of halauxifen-methyl has not yet been reported. Therefore, the aim of the present study was to reveal the mode of action of halauxifen-methyl by exploring its influence on indole-3-acetic acid (IAA) homeostasis and the biosynthesis of ethylene and Abscisic Acid (ABA) in Galium aparine. The results showed that halauxifen-methyl could disrupt the homeostasis of IAA and stimulate the overproduction of ethylene and ABA by inducing the overexpression of the 1-aminocyclopropane-1-carboxylate synthase (ACS) and 9-cis-epoxycarotenoid dioxygenase (NCED) genes involved in ethylene and ABA biosynthesis, finally leading to senescence and plant death. Agronomy. July 2022
Investigating the effect of bacteriophages on bacterial FtsZ localisation
In this study we have used an in vitro meningitis model system for studying the effect of bacteriophages on FtsZ using fluorescent E. coli EV36/FtsZ-mCherry and K12/FtsZ-mNeon strains. We show localisation of FtsZ to the bacterial cell midbody as a single ring during normal growth conditions, and mislocalisation of FtsZ producing filamentous multi-ringed bacterial cells upon addition of the known inhibitor Kil peptide. We also show that when bacteriophages K1F-GFP and T7-mCherry were applied to their respective host strains, these phages can inhibit FtsZ and block bacterial cell division leading to a filamentous multi-ringed phenotype, potentially delaying lysis and increasing progeny number. We present that the ZapA protein is needed for phage inhibition by showing a phenotype recovery with a ZapA mutant strain, and we show that the FtsI protein is also mislocalised upon phage infection. Finally, we show that the T7 peptide gp0.4 is responsible for inhibition of FtsZ in K12 strains by observing a phenotype recovery with a T7∆0.4 mutant.