Potts, M., Sun, H., Mockaitis, K., Kennelly, P. J., Reed, D., Tonks, N. K. (April 1993) A protein-tyrosine/serine phosphatase encoded by the genome of the cyanobacterium Nostoc commune UTEX 584. Journal of Biological Chemistry, 268 (11). pp. 7632-7635. ISSN 0021-9258
Abstract
Protein-tyrosine phosphorylation has long been regarded as an exclusively eukaryotic phenomenon. Although some non-eukaryotes, mainly viruses, possess genes encoding protein-tyrosine kinases or protein-tyrosine phosphatases, these were probably appropriated from the eukaryotic hosts that constitute the sites of action of these enzymes. Herein we identify a gene, iphP, from the chromosome of the cyanobacterium Nostoc commune UTEX 584 that contains the His-Cys-Xaa-Ala-Gly-Xaa-Xaa-Arg sequence characteristic of known protein-tyrosine phosphatases. The expressed gene product, IphP, displayed protein-tyrosine phosphatase activity toward phosphotyrosine residues on reduced, carboxyamidomethylated, and maleylated lysozyme with optimum activity at pH 5.0. In addition, IphP dephosphorylated the phosphoseryl groups on casein that had been phosphorylated by the cAMP-dependent protein kinase. Cell lysates of N. commune probed with antibodies to phosphotyrosine indicated the presence of a tyrosine-phosphorylated protein of M(r) almost-equal-to 85 kDa. This tyrosine-phosphorylated protein was detected in cells grown in the presence of combined nitrogen but not in nitrogen-deficient media that induces the formation of differentiated N2-fixing cells (heterocysts). Together, these data suggest a role for protein-tyrosine phosphorylation in regulating cellular functions in this cyanobacterium. IphP is the first protein-tyrosine phosphatase to be discovered that is encoded by the chromosomal DNA of any prokaryote. Given the free-living nature of N. commune and the phylogenetic antiquity of the cyanobacteria, these findings suggest for the first time the existence of a protein-tyrosine phosphatase of genuine, unambiguous prokaryotic ancestry, thus raising fundamental questions as to the origin and role of tyrosine phosphorylation.
| Item Type: | Paper |
|---|---|
| Uncontrolled Keywords: | AMINO-ACID SEQUENCE ESCHERICHIA-COLI VIRULENCE DETERMINANT HUMAN-PLACENTA RECEPTOR FAMILY YERSINIA GENE |
| Subjects: | bioinformatics > genomics and proteomics > genetics & nucleic acid processing organism description > bacteria bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes bioinformatics > genomics and proteomics > genetics & nucleic acid processing > genomes bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > protein tyrosine phosphatase |
| CSHL Authors: | |
| Communities: | CSHL labs > Tonks lab |
| Depositing User: | Matt Covey |
| Date: | April 1993 |
| Date Deposited: | 17 Dec 2013 17:25 |
| Last Modified: | 17 Dec 2013 17:25 |
| Related URLs: | |
| URI: | https://repository.cshl.edu/id/eprint/29074 |
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