26 research outputs found
L,L-Diaminopimelate Aminotransferase from Chlamydomonas reinhardtii: A Target for Algaecide Development
In some bacterial species and photosynthetic cohorts, including algae, the enzyme
l,l-diaminopimelate aminotransferase
(DapL) (E.C. 2.6.1.83) is involved in the anabolism of the essential amino acid
L-lysine. DapL catalyzes the conversion of
tetrahydrodipicolinate (THDPA) to
l,l-diaminopimelate
(l,l-DAP), in one step bypassing the
DapD, DapC and DapE enzymatic reactions present in the acyl DAP pathways. Here
we present an in vivo and in vitro
characterization of the DapL ortholog from the alga Chlamydomonas
reinhardtii (Cr-DapL). The in
vivo analysis illustrated that the enzyme is able to functionally
complement the E. coli dap auxotrophs and was essential for
plant development in Arabidopsis. In vitro, the enzyme was able
to inter-convert THDPA and l,l-DAP, showing
strong substrate specificity. Cr-DapL was dimeric in both
solution and when crystallized. The structure of Cr-DapL was
solved in its apo form, showing an overall architecture of a
α/β protein with each monomer in the dimer adopting a pyridoxal
phosphate-dependent transferase-like fold in a V-shaped conformation. The active
site comprises residues from both monomers in the dimer and shows some
rearrangement when compared to the apo-DapL structure from
Arabidopsis. Since animals do not possess the enzymatic machinery necessary for
the de novo synthesis of the amino acid
l-lysine, enzymes involved in this pathway are
attractive targets for the development of antibiotics, herbicides and
algaecides
Genomic reconstruction of the SARS-CoV-2 epidemic in England.
The evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus leads to new variants that warrant timely epidemiological characterization. Here we use the dense genomic surveillance data generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of subepidemics that peaked in early autumn 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. The Alpha variant grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed the Alpha variant and eliminated nearly all other lineages in early 2021. Yet a series of variants (most of which contained the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. However, by accounting for sustained introductions, we found that the transmissibility of these variants is unlikely to have exceeded the transmissibility of the Alpha variant. Finally, B.1.617.2/Delta was repeatedly introduced in England and grew rapidly in early summer 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on 26 June 2021
Tomato treatment with chemical inducers reduces the performance of Spodoptera littoralis (Lepidoptera: Noctuidae)
The evolving understanding of plant signaling pathways has promoted the possibility of using chemical inducers as an effective tactic for crop protection. In this study, under greenhouse conditions, we conducted a growth assay of Spodoptera littoralis (Boisduval) larvae on tomato plants treated with BTH (S-methyl benzo [1, 2, 3] thiadiazole 7 carbothioate) as a salicylic acid mimic, PDJ (propyl [1RS, 2RS]-[3-oxo-2-pentylcyclopentyl] acetate) as a jasmonic acid-mimic or both chemicals as a combined treatment. The larval body weight of S. littoralis was drastically reduced with each chemical compared to control plants, and there was a significant synergistic interaction. Overall, the total weight gain of surviving larvae fed on treated plants was distinctly tenfold less than for those fed on control plants. Moreover, incorporating the chemical inducers in artificial diets had no direct or toxic impact on the larval body weight of S. littoralis under laboratory conditions. Larval survival rates were significantly lower (35–40 %) on treated plants with either combined or independent inducers’ treatments compared with control plants after 15-day feeding. In contrast, incorporating the chemical inducers in artificial diets had no direct effect on larval survival rates under laboratory conditions. The applied concentrations of BTH and PDJ had no detectable phytotoxicity to tomato plants. Our results demonstrate that BTH and PDJ can act synergistically when applied to tomato to reduce the performance of S. littoralis. These findings stress that the application of chemical inducers could provide an environment-friendly tactic to help manage insect pests and thereby play multiple roles in improving the overall plant resistance to herbivore pests