This Article Full Text Full Text (PDF) Other Versions of this Article: JB.00323-07v1 189/14/5075    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Shi, L. Articles by Zhang, C.-C. Search for Related Content PubMed PubMed Citation Articles by Shi, L. Articles by Zhang, C.-C.

 Previous Article  |  Next Article 

Journal of Bacteriology, July 2007, p. 5075-5081, Vol. 189, No. 14
0021-9193/07/$08.00+0     doi:10.1128/JB.00323-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Two Genes Encoding Protein Kinases of the HstK Family Are Involved in Synthesis of the Minor Heterocyst-Specific Glycolipid in the Cyanobacterium Anabaena sp. Strain PCC 7120

Lei Shi,¹ Jian-Hong Li,^2, Yong Cheng,¹ Li Wang,¹ Wen-Li Chen,¹ and Cheng-Cai Zhang^1,2*

National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China,¹ Laboratoire de Chimie Bactérienne, UPR9043, IBSM-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France²

Received 4 March 2007/ Accepted 8 May 2007

The filamentous cyanobacterium Anabaena sp. strain PCC 7120 can fix N₂ under oxic conditions, and the activity of nitrogen fixation occurs exclusively in heterocysts, cells differentiated from vegetative cells in response to a limitation of a combined-nitrogen source in the growth medium. At the late stages of heterocyst differentiation, an envelope layer composed of two glycolipids is formed to limit the entry of oxygen so that the oxygen-sensitive nitrogenase can function. The genome of Anabaena sp. strain PCC 7120 possesses a family of 13 genes (the hstK family), all encoding proteins with a putative Ser/Thr kinase domain at their N termini and a His-kinase domain at their C termini. In this study, we showed that the double mutant D4.3 strain, in which two members of this gene family, pkn44 (all1625) and pkn30 (all3691), were both inactivated, failed to fix N₂ in the presence of oxygen (Fox^–). In an environment without oxygen, a low level of nitrogenase activity was detectable (Fix⁺). Heterocyst development in the mutant D4.3 was delayed by 24 h and arrested at a relatively early stage without the formation of the glycolipid layer (Hgl^–). Only the minor species of the two heterocyst-specific glycolipids (HGLs) was missing in the mutant. We propose that DevH, a putative transcription factor, coordinates the synthesis of both HGLs, while Pkn44/Pkn30 and the previously characterized PrpJ may represent two distinct regulatory pathways involved in the synthesis of the minor HGL and the major HGL, respectively.

Published ahead of print on 18 May 2007.

Present address: Jiangsu Provincial Key Laboratory of Biodiversity and Biotechnology, Nanjing Normal University, Nanjing 210097, People's Republic of China.