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Applied and Environmental Microbiology, January 2006, p. 245-251, Vol. 72, No. 1
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.1.245-251.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

A Lithium-Sensitive and Sodium-Tolerant 3'-Phosphoadenosine-5'-Phosphatase Encoded by halA from the Cyanobacterium Arthrospira platensis Is Closely Related to Its Counterparts from Yeasts and Plants

Ju-Yuan Zhang,1,{dagger} Jie Zou,1,{dagger} Qiyu Bao,2 Wen-Li Chen,1 Li Wang,1 Huanming Yang,3 and Cheng-Cai Zhang1,4*

National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China,1 Institute of Biomedical Informatics, Wenzhou Medical College, Wenzhou 325000, People's Republic of China,2 Beijing Genomics Institute, Chinese Academy of Sciences, Beijing 101300, People's Republic of China,3 Laboratoire de Chimie Bactérienne, IBSM, CNRS-UPR9043, 31 Chemin Joseph Aiguie, 13402 Marseille Cedex 20, France4

Received 13 September 2005/ Accepted 29 October 2005

3'-Phosphoadenosine-5'-phosphatase (PAPase) is required for the removal of toxic 3'-phosphoadenosine-5'-phosphate (PAP) produced during sulfur assimilation in various eukaryotic organisms. This enzyme is a well-known target of lithium and sodium toxicity and has been used for the production of salt-resistant transgenic plants. In addition, PAPase has also been proposed as a target in the treatment of manic-depressive patients. One gene, halA, which could encode a protein closely related to the PAPases of yeasts and plants, was identified from the cyanobacterium Arthrospira (Spirulina) platensis. Phylogenic analysis indicated that proteins related to PAPases from several cyanobacteria were found in different clades, suggesting multiple origins of PAPases in cyanobacteria. The HalA polypeptide from A. platensis was overproduced in Escherichia coli and used for the characterization of its biochemical properties. HalA was dependent on Mg2+ for its activity and could use PAP or 3'-phosphoadenosine-5'-phosphosulfate as a substrate. HalA is sensitive to Li+ (50% inhibitory concentration [IC50] = 3.6 mM) but only slightly sensitive to Na+ (IC50 = 600 mM). The salt sensitivity of HalA was thus different from that of most of its eukaryotic counterparts, which are much more sensitive to both Li+ and Na+, but was comparable to the PAPase AtAHL (Hal2p-like protein) from Arabidopsis thaliana. The properties of HalA could help us to understand the structure-function relationship underlying the salt sensitivity of PAPases. The expression of halA improved the Li+ tolerance of E. coli, suggesting that the sulfur-assimilating pathway is a likely target of salt toxicity in bacteria as well.

* Corresponding author. Mailing address: Laboratoire de Chimie Bactérienne, CNRS-UPR9043, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France. Phone: 33 4 91164096. Fax: 33 4 91718914. E-mail: cczhang{at}ibsm.cnrs-mrs.fr

{dagger} J.-Y.Z. and J.Z. contributed equally to this work.

Applied and Environmental Microbiology, January 2006, p. 245-251, Vol. 72, No. 1
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.1.245-251.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Zhang, J.-Y., Chen, W.-L., Zhang, C.-C. (2009). hetR and patS, two genes necessary for heterocyst pattern formation, are widespread in filamentous nonheterocyst-forming cyanobacteria. Microbiology 155: 1418-1426 [Abstract] [Full Text]  


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