This Article Full Text (PDF) 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by McCartney, B. Articles by Potts, M. Search for Related Content PubMed PubMed Citation Articles by McCartney, B. Articles by Potts, M.

 Previous Article  |  Next Article 

J. Bacteriol., 04 1997, 2314-2318, Vol 179, No. 7
Copyright © 1997, American Society for Microbiology

Protein tyrosine phosphorylation in the cyanobacterium Anabaena sp. strain PCC 7120

B McCartney, LD Howell, PJ Kennelly and M Potts
Department of Biochemistry and Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.

Components of a protein tyrosine phosphorylation/dephosphorylation network were identified in the cyanobacterium Anabaena sp. strain PCC 7120. Three phosphotyrosine (P-Tyr) proteins of 27, 36, and 52 kDa were identified through their conspicuous immunoreactions with RC20H monoclonal antibodies specific for P-Tyr. These immunoreactions were outcompeted completely by free P-Tyr (5 mM) but not by phosphoserine or phosphothreonine. The P-Tyr content of the three major P-Tyr proteins and several minor proteins increased with their time of incubation in the presence of Mg-ATP and the protein phosphatase inhibitors sodium orthovanadate and sodium fluoride. Incubation of the same extracts with [gamma-32P]ATP but not [alpha-32P]ATP led to the phosphorylation of five polypeptides with molecular masses of 20, 27, 52, 85, and 100 kDa. Human placental protein tyrosine phosphatase 1B, with absolute specificity for P-Tyr, liberated significant quantities of 32Pi from four of the polypeptides, confirming that a portion of the protein- bound phosphate was present as 32P-Tyr. Alkaline phosphatase and the dual-specificity protein phosphatase IphP from the cyanobacterium Nostoc commune UTEX 584 also dephosphorylated these proteins and did so with greater apparent efficiency. Two of the polypeptides were partially purified, and phosphoamino analysis identified 32P-Tyr, [32P]phosphoserine, and [32P]phosphothreonine. Anabaena sp. strain PCC 7120 cell extracts contained a protein tyrosine phosphatase activity that was abolished in the presence of sodium orthovanadate and inhibited significantly by the sulfhydryl-modifying agents p- hydroxymercuriphenylsulfonic acid and p-hydroxymercuribenzoate as well as by heparin. In Anabaena sp. strain PCC 7120 the presence and/or phosphorylation status of P-Tyr proteins was influenced by incident photon flux density.

This article has been cited by other articles:

• Nishiwaki, T., Iwasaki, H., Ishiura, M., Kondo, T. (2000). Nucleotide binding and autophosphorylation of the clock protein KaiC as a circadian timing process of cyanobacteria. Proc. Natl. Acad. Sci. USA 97: 495-499 [Abstract] [Full Text]  
• Brimer, C. D., Montie, T. C. (1998). . J. Bacteriol. 180: 3209-3217 [Abstract]  
• Sültemeyer, D., Klughammer, B., Badger, M. R., Dean Price, G. (1998). Fast Induction of High-Affinity HCO3- Transport in Cyanobacteria. Plant Physiol. 116: 183-192 [Abstract] [Full Text]