Biologia, Bratislava, 57/Suppl. 11: 137-148, 2002.
ISSN 0006-3088 (Biologia).
Characterisation of putative a-amylases from apple (Malus domestica) and Arabidopsis thaliana.
Duncan Stanley1,2, Anna M. Fitzgerald2, Kevin J. F. Farnden1 & Elspeth A. MacRae2*
1 Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
2 HortResearch, Mt Albert Research Centre, Private Bag 92169, Auckland, New Zealand; tel.: ++ 649 815 4200, fax: ++ 649 815 4202, e-mail: EMacRae@hortresearch.co.nz
Received: October 4, 2001 / Accepted: February 12, 2002
We have identified a number of new plant a-amylase-like genes from apple and Arabidopsis thaliana, two of which appear to be completely novel. The putative products of these novel genes are characterised by a large (460-480 amino acid) N-terminal extension, which includes a putative plastid-targeting peptide. Phylogenetic analysis of these and other a-amylase-like genes from plants suggests that there are three distinct families of a-amylases in plants. These three families can also be separated on the basis of their intron structure, the relative size of domain B, and their predicted subcellular targeting. All three of the gene families appear to have the catalytic residues necessary for a-amylase activity, although it is possible that each may have different substrate specificity. Furthermore, each gene family appears to be targeted to different compartments within the cell. ESTs corresponding to each of the families have been identified in the gymnosperm Pinus taeda, suggesting that the three gene families diverged from each other prior to the angiosperm/gymnosperm split.
Key words: a-amylase, Arabidopsis thaliana, intron structure, Malus domestica, phylogeny, subcellular localisation.