Abstract
Purple acid phosphatases (PAPs) are members of the metallo-phosphoesterase family. They are characterized by the presence of seven conserved amino acid residues involved in coordinating the dimetal nuclear center in their reactive site. We compared the 29 PAPs predicted for Arabidopsis thaliana in their varieties of potential metal-ligating residues. Although 24 members possessed sets of metal-ligating residues typical of known PAPs, 1 member lacked four of the seven residues. For the remaining four members, potential metal-ligating residues were generally more similar to those in metal-dependent exonucleases and related proteins. Evidence was obtained for the expression of the majority of the 29 PAPs. To facilitate future investigations, a scheme for naming Arabidopsis PAPs and a system for classifying the 29 PAPs are proposed. The cDNA sequences and the responses to phosphate deprivation of seven Arabidopsis PAPs (AtPAP7-AtPAP13) were characterized. For some AtPAPs analyzed, there were fully processed transcripts as well as splice variants. The splice variants of AtPAP10 were found to associate with polyribosomes and may be translated into a NH(2)-terminal truncated protein. Phylogenetic investigations showed that AtPAPs 7 and 8, together with similar enzymes from other plant species, formed the low molecular weight plant PAP group. Members of this group were more closely related to PAPs from mammalian cells. AtPAPs 9-13, together with kidney bean PAP, formed the high molecular weight PAP group. In phosphate deprivation experiments, gene transcription of AtPAP11 and AtPAP12 was induced and increased, respectively, whereas that of the remaining five AtPAPs was not affected by phosphate deprivation. The present work demonstrates that structure variation and expression regulation of plant PAPs are more complex than previously described and provides a framework for comprehensive molecular genetic and biochemical studies of all Arabidopsis PAPs in the future.
Highlights
Purple acid phosphatases (PAPs) are members of the metallo-phosphoesterase family
In this paper we report the finding of more Arabidopsis PAP members from data base searching, comparative analysis of conserved metal-ligating amino acid residues in 29 PAPs, and propose schemes for naming and classifying these PAPs
A Represented by the AGI code. b Bacterial artificial chromosome (BAC) locus number is obtained from the the Institute for Genomic Research (TIGR) data base. c The predicted protein sequence differ from the one deduced from cDNA analysis. d This element is not present in AGI predicted protein sequence owing to error in coding sequence prediction
Summary
The complement of amino acid residues involved in metal ligation in different types of metallo-phosphoesterases has recently been investigated based on the alignment of conserved sequence motifs. We have selected the model plant species A. thaliana in our studies on higher plant PAPs. A search of the annotated genome data base of Arabidopsis reveals that, in addition to PAP genes, this species contains genes encoding several other types of phosphatases that may share some similarities with PAPs in reacting to physiological and environmental cues. In this paper we report the finding of more Arabidopsis PAP members from data base searching, comparative analysis of conserved metal-ligating amino acid residues in 29 PAPs, and propose schemes for naming and classifying these PAPs. We describe cDNA cloning and amino acid sequence analysis for seven PAPs encoded by chromosome 2. Based on the work presented here, effective strategies for further studies of Arabidopsis PAPs are discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
