Abstract
Phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase constitute a family of tetrahydropterin-dependent aromatic amino acid hydroxylases. It has been proposed that each hydroxylase is composed of a conserved C-terminal catalytic domain and an unrelated N-terminal regulatory domain. Of the three, only tyrosine hydroxylase is activated by heparin and binds to heparin-Sepharose. A series of N-terminal deletion mutants of tyrosine hydroxylase has been expressed in Escherichia coli to identify the heparin-binding site. The mutants lacking the first 32 or 68 amino acids bind to heparin-Sepharose. The mutant lacking 76 amino acids binds somewhat to heparin-Sepharose and the proteins lacking 88 or 128 do not bind at all. Therefore, an important segment of the heparin-binding site must be composed of the region from residues 76 to 90. All of the deletion mutants are active, and the Michaelis constants for pterins and tyrosine are similar among all the mutant and wild-type enzymes.
Full Text
The Full Text of this article is available as a PDF (374.9 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Abate C., Joh T. H. Limited proteolysis of rat brain tyrosine hydroxylase defines an N-terminal region required for regulation of cofactor binding and directing substrate specificity. J Mol Neurosci. 1991;2(4):203–215. [PubMed] [Google Scholar]
- Brown E. R., Coker G. T., 3rd, O'Malley K. L. Organization and evolution of the rat tyrosine hydroxylase gene. Biochemistry. 1987 Aug 11;26(16):5208–5212. doi: 10.1021/bi00390a046. [DOI] [PubMed] [Google Scholar]
- Campbell D. G., Hardie D. G., Vulliet P. R. Identification of four phosphorylation sites in the N-terminal region of tyrosine hydroxylase. J Biol Chem. 1986 Aug 15;261(23):10489–10492. [PubMed] [Google Scholar]
- Daubner S. C., Lauriano C., Haycock J. W., Fitzpatrick P. F. Site-directed mutagenesis of serine 40 of rat tyrosine hydroxylase. Effects of dopamine and cAMP-dependent phosphorylation on enzyme activity. J Biol Chem. 1992 Jun 25;267(18):12639–12646. [PubMed] [Google Scholar]
- Daubner S. C., Lohse D. L., Fitzpatrick P. F. Expression and characterization of catalytic and regulatory domains of rat tyrosine hydroxylase. Protein Sci. 1993 Sep;2(9):1452–1460. doi: 10.1002/pro.5560020909. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Grenett H. E., Ledley F. D., Reed L. L., Woo S. L. Full-length cDNA for rabbit tryptophan hydroxylase: functional domains and evolution of aromatic amino acid hydroxylases. Proc Natl Acad Sci U S A. 1987 Aug;84(16):5530–5534. doi: 10.1073/pnas.84.16.5530. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Grima B., Lamouroux A., Blanot F., Biguet N. F., Mallet J. Complete coding sequence of rat tyrosine hydroxylase mRNA. Proc Natl Acad Sci U S A. 1985 Jan;82(2):617–621. doi: 10.1073/pnas.82.2.617. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Lohse D. L., Fitzpatrick P. F. Identification of the intersubunit binding region in rat tyrosine hydroxylase. Biochem Biophys Res Commun. 1993 Dec 30;197(3):1543–1548. doi: 10.1006/bbrc.1993.2653. [DOI] [PubMed] [Google Scholar]
- Studier F. W., Rosenberg A. H., Dunn J. J., Dubendorff J. W. Use of T7 RNA polymerase to direct expression of cloned genes. Methods Enzymol. 1990;185:60–89. doi: 10.1016/0076-6879(90)85008-c. [DOI] [PubMed] [Google Scholar]
- Vigny A., Henry J. P. Bovine adrenal tyrosine hydroxylase: comparative study of native and proteolyzed enzyme, and their interaction with anions. J Neurochem. 1981 Feb;36(2):483–489. doi: 10.1111/j.1471-4159.1981.tb01618.x. [DOI] [PubMed] [Google Scholar]
- Zigmond R. E., Schwarzschild M. A., Rittenhouse A. R. Acute regulation of tyrosine hydroxylase by nerve activity and by neurotransmitters via phosphorylation. Annu Rev Neurosci. 1989;12:415–461. doi: 10.1146/annurev.ne.12.030189.002215. [DOI] [PubMed] [Google Scholar]