Abstract
Screening of a genomic library from tomato plants (Lycopersicon esculentum) with a cDNA probe encoding a subtilisin-like protease (PR-P69) that is induced at the transcriptional level following pathogen attack (Tornero, P., Conejero, V., and Vera, P. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 6332-6337) resulted in the isolation of a cluster of genomic clones that comprise a tandem of four different subtilisin-like protease genes (P69A, P69B, P69C, and P69D). Sequence analyses and comparison of the encoded proteins revealed that all are closely related (79 to 88% identity), suggesting that all are derived from a common ancestral gene. mRNA expression analysis as well as studies of transgenic plants transformed with promoter-beta-glucuronidase fusions for each of these genes revealed that the four genes exhibit differential transcriptional regulation and expression patterns. P69A and P69D are expressed constitutively, but with different expression profiles during development, whereas the P69B and P69C genes show expression following infection with Pseudomonas syringae and are also up-regulated by salicylic acid. We propose that these four P69-like proteases, as members of a complex gene family of plant subtilisin-like proteases, may be involved in a number of specific proteolytic events that occur in the plant during development and/or pathogenesis.
Highlights
Proteolysis is fundamental for the normal functioning of multicellular organisms and plays key roles in a variety of processes such as development, physiology, defense and stress responses, and adaptation to the changing environment
While the four clustered proteases exhibit a high degree of amino acid sequence identity, we show that they are differentially regulated at the transcriptional level, each showing a different expression pattern, either during normal plant development or following pathogenic attack
We provide structural and functional information on a genomic cluster comprising four different members of a family of plant genes, which on the basis of amino acid sequence conservation and structural organization are related to the subtilisin-like protease clan (EC 3.4.21.14) [11]
Summary
Proteolysis is fundamental for the normal functioning of multicellular organisms and plays key roles in a variety of processes such as development, physiology, defense and stress responses, and adaptation to the changing environment. While the four clustered proteases exhibit a high degree of amino acid sequence identity, we show that they are differentially regulated at the transcriptional level, each showing a different expression pattern, either during normal plant development or following pathogenic attack.
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