, Volume 198, Issue 1, pp 64-69

Cytosolic ascorbate peroxidase from Arabidopsis thaliana L. is encoded by a small multigene family

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Abstract

A second cytosolic ascorbate peroxidase (cAPX; EC 1.11.1.11) gene from Arabidopsis thaliana has been characterised. This second gene (designated APX1b) maps to linkage group 3 and potentially encodes a cAPX as closely related to that from other dicotyledonous species as to the other member of this gene family (Kubo et al, 1993, FEBS Lett 315: 313–317; here designated APX1a), which maps to linkage group 1. In contrast, the lack of sequence similarity in non-coding regions of the genes implies that they are differentially regulated. Under non-stressed conditions only APX1a is expressed. APX1b was identified during low-stringency probing using a cDNA coding for pea cAPX which, in turn, was recovered from a cDNA library by immunoscreening with an antiserum raised against tea plastidial APX (pAPX). No pAPX cDNAs were recovered, despite the antiserum displaying specificity for pAPX in Western blots.

Accession numbers: The APX1b sequence is in the EMBL database under accession number X80036
M.S. gratefully acknowledges the support from the Junta Nacional de Investigaçâo Cientifica e Tecnológia, Portugal (grant number BD/394/90-IE). This work was supported by the Biotechnological and Biological Sciences Research Council through a grant-in-aid to the John Innes Centre.