Selective Inhibition of Proline Hydroxylation by 3,4-Dehydroproline

• Published in: Plant physiology (Bethesda) Vol. 73; no. 2; pp. 324 - 328
• Main Authors: Cooper, James B., Varner, Joseph E.
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-10-1983
• Subjects: Amino acids; Biological and medical sciences; Cell growth; Cell walls; Enzymes; Fundamental and applied biological sciences. Psychology; Glycoproteins; Metabolism; Metabolism. Physicochemical requirements; Nitrates; Plant physiology and development; Plant roots; Plants; Protein synthesis; Tritium; Daucus carota; Structure activity relation; Dicotyledones; Angiospermae; Glycoprotein; Spermatophyta; Umbelliferae; Metabolic inhibitor
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.73.2.324

The effect of proline analogs on peptidyl proline hydroxylation has been studied in vivo using aerated root slices of Daucus carota. One analog, 3,4-dehydroproline, acted at micromolar concentrations to rapidly and selectively inhibit peptidyl proline hydroxylation. A structurally altered hydroxyproline-rich cell wall glycoprotein was synthesized and secreted by dehydroproline-treated tissue. The capacity to hydroxylate proline recovered slowly following a short pulse treatment with the analog, with a halftime for recovery of about 24 hours. Recovery was not altered by supplying exogenous proline. Dehydroproline had little effect on the induction of nitrate reductase by nitrate, nor on wound-induced increases in amino acid uptake and protein synthesis. In contrast, other proline analogs inhibit proline hydroxylation only at millimolar concentrations. It is hypothesized that dehydroproline acts as an enzyme-activated suicide inhibitor of prolyl hydroxylase. This analog should become a useful tool for elucidating the functional significance of hydroxyproline-rich glycoproteins.