Leucine aminopeptidases: the ubiquity of LAP-N and the specificity of LAP-A.
The wound-induced leucine aminopeptidase (EC 3.4.11.1) genes, LapA1 and LapA2, from tomato (Lycopersicon esculentum Mill.) were isolated and characterized. The genes were organized in a tandem array with approximately 6 kb separating their coding regions. Quantitation of LapA mRNA levels in conjunction with nuclear run-on experiments indicated that LapA genes were primarily under transcriptional control after wounding and infection with Pseudomonas syringae pv. tomato. In contrast, actin genes were down-regulated after pathogen infection. The sequences of the LapA1 and LapA2 5'-flanking regions were determined and several potential regulatory motifs were identified. Ribonuclease protection studies revealed that LapA1 and LapA2 had short 18-bp 5'-untranslated regions (UTR), both genes were expressed after wounding, and LapA1 mRNAs were 3.3-fold more abundant than LapA2 transcripts. While the region surrounding LapA1 was conserved, the 3'-UTRs and 3'-flanking regions of LapA2 had diverged in two inbred tomato lines. The accumulation of LapA mRNAs and of LAP-A (acidic pI), LAP-N (neutral pI) and LAP-related proteins were examined in two monocot and five dicot species. The LAP-N and 66- and 77-kDa LAP-related proteins were detected in healthy and wounded leaves of all plants examined. The LAP-A proteins were only detected in nightshade and their accumulation was distinct from that observed in tomato.
Chao
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Department of Botany and Plant Sciences and Interdepartmental Program in Genetics, University of California, Riverside 92521-0124, USA.
Pautot
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Holzer
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Walling
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D020413:3' Untranslated Regions; D020816:Amino Acid Motifs; D001483:Base Sequence; D007931:Leucyl Aminopeptidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D018551:Solanum lycopersicum / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D018749:RNA, Plant / Q000032:analysis; D016415:Sequence Alignment
D020413:3' Untranslated Regions; D010940:Plant Proteins; D018749:RNA, Plant; D007931:Leucyl Aminopeptidase