Construction of cryptogein mutants, a proteinaceous elicitor from Phytophthora, with altered abilities to induce a defense reaction in tobacco cells.
We prepared a series of cryptogein mutants, an elicitor from Phytophthora cryptogea, with altered abilities to bind sterols and fatty acids. The induction of the early events, i.e., synthesis of active oxygen species and pH changes, in suspension tobacco cells by these mutated proteins was proportional to their ability to bind sterols but not fatty acids. Although the cryptogein-sterol complex was suggested to be a form triggering a defense reaction in tobacco, some proteins unable to bind sterols induced the synthesis of active oxygen species and pH changes. The modeling experiments showed that conformational changes after the introduction of bulky residues into the omega loop of cryptogein resemble those induced by sterol binding. These changes may be necessary for the ability to trigger the early events by elicitins. However, the ability to stimulate necrosis in suspension tobacco cells and the expression of defense proteins in tobacco plants were linked neither to the lipid binding capacity nor to the capacity to provoke the early events. On the basis of these experiments and previous results, we propose that elicitins could stimulate two signal pathways. The first one induces necroses and the expression of pathogen-related proteins, includes tyrosine protein kinases and mitogen-activated protein kinases, and depends on the overall structure and charge distribution. The second type of interaction is mediated by phospholipase C and protein kinase C. It triggers the synthesis of active oxygen species and pH changes. This interaction depends on the ability of elicitins to bind sterols.
Lochman
Jan
J
Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic.
Kasparovsky
Tomas
T
Damborsky
Jiri
J
Osman
Hanan
H
Marais
Antoine
A
Chaloupkova
Radka
R
Ponchet
Michel
M
Blein
Jean-Pierre
JP
Mikes
Vladimir
V
D020418:Algal Proteins / Q000138:chemical synthesis* / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity; D002942:Circular Dichroism; D003198:Computer Simulation; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005656:Fungal Proteins; D050356:Lipid Metabolism; D016297:Mutagenesis, Site-Directed; D009183:Mycotoxins / Q000138:chemical synthesis / Q000235:genetics / Q000633:toxicity; D019255:NADPH Oxidases / Q000096:biosynthesis; D010650:Phenylalanine Ammonia-Lyase / Q000096:biosynthesis; D010838:Phytophthora / Q000235:genetics* / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000096:biosynthesis; D011485:Protein Binding / Q000235:genetics; D011506:Proteins; D021281:Quantitative Structure-Activity Relationship; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000138:chemical synthesis / Q000235:genetics / Q000633:toxicity; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology / Q000378:metabolism / Q000382:microbiology*
D020418:Algal Proteins; D005227:Fatty Acids; D005656:Fungal Proteins; D009183:Mycotoxins; D010940:Plant Proteins; D011506:Proteins; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; C061032:cryptogein protein, Phytophthora cryptogea; C085101:elicitin, Phytophthora; C053376:pathogenesis-related proteins, plant; C010905:dehydroergosterol; D019255:NADPH Oxidases; D010650:Phenylalanine Ammonia-Lyase; D004875:Ergosterol