Phosphorylation of ferredoxin and regulation of renal mitochondrial 25-hydroxyvitamin D-1α-hydroxylase activity in vitro

R. Nemani, J. G. Ghazarian, B. Moorthy, N. Wongsurawat, John R Strong, H. J. Armbrecht

Research output: Contribution to journalArticle

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Abstract

The kidney is the principal physiologic site of production of biologically active 1,25-dihydroxyvitamin D. The 25-hydroxyvitamin D-1α-hydroxylase (1-OHase) activity found in renal mitochondria is under tight hormonal control. Parathyroid hormone stimulates the renal conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D in young animals, which is accompanied by dephosphorylation of ferredoxin (Fx), a component of the mitochondrial 1-OHase enzyme complex (Siegel, N., Wongsurawat, N., and Armbrecht, H.J. (1986) J. Biol. Chem. 261, 16998-17003). The present study investigates the capacity of Fx to be phosphorylated in vitro and to modulate the 1-OHase activity of a reconstituted system. Fx was phosphorylated by renal mitochondrial type II protein kinase. Phosphorylation did not alter Fx mobility on sodium dodecyl sulfate gels but did decrease the pI as measured by isoelectric focusing. Amino acid analysis demonstrated that 1 mol of serine and 1 mol of threonine were phosphorylated per mol of Fx. Peptide mapping of phosphorylated Fx was consistent with phosphorylation of serinr 88 and threonine 85 or 97. Fx was selectively dephosphorylated by rabbit skeletal muscle protein phosphatase C2 but not C1. Phosphorylation of Fx significantly inhibited the 1-OHase activity of a reconstituted system consisting of Fx reductase, Fx, and renal mitochondrial cytochrome P-450. These findings suggest that phosphorylation/dephosphorylation of Fx may play a role in modulating renal 1,25-dihydroxyvitamin D production.

Original languageEnglish (US)
Pages (from-to)15361-15366
Number of pages6
JournalJournal of Biological Chemistry
Volume264
Issue number26
StatePublished - 1989
Externally publishedYes

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Ferredoxins
Phosphorylation
Mixed Function Oxygenases
Kidney
Threonine
25-hydroxyvitamin D
In Vitro Techniques
Mitochondria
Peptide Mapping
Muscle Proteins
Phosphoprotein Phosphatases
Mitochondrial Proteins
Isoelectric Focusing
Parathyroid Hormone
Sodium Dodecyl Sulfate
Cytochrome P-450 Enzyme System
Protein Kinases
Serine
Oxidoreductases
Animals

ASJC Scopus subject areas

  • Biochemistry

Cite this

Nemani, R., Ghazarian, J. G., Moorthy, B., Wongsurawat, N., Strong, J. R., & Armbrecht, H. J. (1989). Phosphorylation of ferredoxin and regulation of renal mitochondrial 25-hydroxyvitamin D-1α-hydroxylase activity in vitro. Journal of Biological Chemistry, 264(26), 15361-15366.

Phosphorylation of ferredoxin and regulation of renal mitochondrial 25-hydroxyvitamin D-1α-hydroxylase activity in vitro. / Nemani, R.; Ghazarian, J. G.; Moorthy, B.; Wongsurawat, N.; Strong, John R; Armbrecht, H. J.

In: Journal of Biological Chemistry, Vol. 264, No. 26, 1989, p. 15361-15366.

Research output: Contribution to journalArticle

Nemani, R, Ghazarian, JG, Moorthy, B, Wongsurawat, N, Strong, JR & Armbrecht, HJ 1989, 'Phosphorylation of ferredoxin and regulation of renal mitochondrial 25-hydroxyvitamin D-1α-hydroxylase activity in vitro', Journal of Biological Chemistry, vol. 264, no. 26, pp. 15361-15366.
Nemani, R. ; Ghazarian, J. G. ; Moorthy, B. ; Wongsurawat, N. ; Strong, John R ; Armbrecht, H. J. / Phosphorylation of ferredoxin and regulation of renal mitochondrial 25-hydroxyvitamin D-1α-hydroxylase activity in vitro. In: Journal of Biological Chemistry. 1989 ; Vol. 264, No. 26. pp. 15361-15366.
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