A Second Kazal-like protease inhibitor from Phytophthora infestans inhibits and interacts with the apoplastic pathogenesis-related protease P69B of tomato.
The plant apoplast forms a protease-rich environment in which proteases are integral components of the plant defense response. Plant pathogenic oomycetes, such as the potato (Solanum tuberosum) and tomato (Lycopersicon esculentum) pathogen Phytophthora infestans, secrete a diverse family of serine protease inhibitors of the Kazal family. Among these, the two-domain EPI1 protein was shown to inhibit and interact with the pathogenesis-related protein P69B subtilase of tomato and was implicated in counter-defense. Here, we describe and functionally characterize a second extracellular protease inhibitor, EPI10, from P. infestans. EPI10 contains three Kazal-like domains, one of which was predicted to be an efficient inhibitor of subtilisin A by an additivity-based sequence to reactivity algorithm (Laskowski algorithm). The epi10 gene was up-regulated during infection of tomato, suggesting a potential role during pathogenesis. Recombinant EPI10 specifically inhibited subtilisin A among the major serine proteases, and inhibited and interacted with P69B subtilase of tomato. The finding that P. infestans evolved two distinct and structurally divergent protease inhibitors to target the same plant protease suggests that inhibition of P69B could be an important infection mechanism for this pathogen.
Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA.
Miaoying
M
Tian
Brett
B
Benedetti
Sophien
S
Kamoun
D000595:Amino Acid Sequence; D001483:Base Sequence; D002918:Chymotrypsin / Q000378:metabolism; D017931:DNA Primers; D018551:Solanum lycopersicum / Q000382:microbiology*; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010838:Phytophthora / Q000737:chemistry / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013381:Subtilisins / Q000037:antagonists & inhibitors; D014357:Trypsin / Q000378:metabolism; D014359:Trypsin Inhibitor, Kazal Pancreatic / Q000302:isolation & purification* / Q000494:pharmacology
D017931:DNA Primers; D010940:Plant Proteins; D014359:Trypsin Inhibitor, Kazal Pancreatic; D010447:Peptide Hydrolases; D013381:Subtilisins; D002918:Chymotrypsin; D014357:Trypsin