Molecular phenotyping of lignin-modified tobacco reveals associated changes in cell-wall metabolism, primary metabolism, stress metabolism and photorespiration

Agrobacterium tumefaciens-mediated random insertional mutagenesis was used to investigate pathogenicity determinants in Leptosphaeria maculans. One tagged nonpathogenic mutant, termed m186, is analyzed in detail here. Microscopic analyses of infected plant tissues revealed that m186 is specifically blocked at the invasive growth phase after an unaffected initial penetration stage and is unable to switch to the necrotrophic lifestyle. In addition, m186 exhibits an altered cell wall and seems to be affected in its ability to produce cell-wall-degrading enzymes. The T-DNA insertion occurs in the intergenic region between two head-to-tail genes, leading to a constitutive upregulation of their expression. Complementation experiments showed that only one of these two genes, Lmepi, fully accounts for the mutant phenotype. Bioinformatics and expression analyses along with functional studies suggested that the Lmepi gene encodes for the highly conserved UDP-glucose-4-epimerase, a key enzyme of the Leloir pathway involved in galactose metabolism. For the third time, this study highlights the intimate connection between primary metabolism and pathogenicity in L. maculans. This finding, along with similar data obtained from the related species Stagonospora nodorum, indicates the importance of in planta nutrition for the success of infection of plants by fungi belonging to class Dothideomycete.

Download Full-text

Solid-state 15N NMR studies of the effects of penicillin on cell-wall metabolism of Aerococcusviridans (Gaffkyahomari)

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(85)90285-2 ◽

1985 ◽

Vol 126 (3) ◽

pp. 1006-1012 ◽

Cited By ~ 13

Author(s):

G.Edwin Wilson ◽

Gary S. Jacob ◽

Jacob Schaefer

Keyword(s):

Cell Wall ◽

Solid State ◽

15N Nmr ◽

Cell Wall Metabolism ◽

Nmr Studies

Download Full-text

Synergism of imipenem with fosfomycin associated with the active cell wall recycling and heteroresistance in Acinetobacter calcoaceticus-baumannii complex

Scientific Reports ◽

10.1038/s41598-021-04303-7 ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Uthaibhorn Singkham-in ◽

Tanittha Chatsuwan

Keyword(s):

Cell Wall ◽

De Novo ◽

Acinetobacter Calcoaceticus ◽

Active Cell ◽

Wild Type ◽

Cell Wall Metabolism ◽

Carbapenem Resistant ◽

Type Form ◽

Wild Type Form ◽

Cell Wall Recycling

AbstractThe carbapenem-resistant Acinetobacter calcoaceticus-baumannii (ACB) complex has become an urgent threat worldwide. Here, we determined antibiotic combinations and the feasible synergistic mechanisms against three couples of ACB (A. baumannii (AB250 and A10), A. pittii (AP1 and AP23), and A. nosocomialis (AN4 and AN12)). Imipenem with fosfomycin, the most effective in the time-killing assay, exhibited synergism to all strains except AB250. MurA, a fosfomycin target encoding the first enzyme in the de novo cell wall synthesis, was observed with the wild-type form in all isolates. Fosfomycin did not upregulate murA, indicating the MurA-independent pathway (cell wall recycling) presenting in all strains. Fosfomycin more upregulated the recycling route in synergistic strain (A10) than non-synergistic strain (AB250). Imipenem in the combination dramatically downregulated the recycling route in A10 but not in AB250, demonstrating the additional effect of imipenem on the recycling route, possibly resulting in synergism by the agitation of cell wall metabolism. Moreover, heteroresistance to imipenem was observed in only AB250. Our results indicate that unexpected activity of imipenem on the active cell wall recycling concurrently with the presence of heteroresistance subpopulation to imipenem may lead to the synergism of imipenem and fosfomycin against the ACB isolates.

Download Full-text