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PubMed1994

A style-specific hydroxyproline-rich glycoprotein with properties of both extensins and arabinogalactan proteins.

A basic, hydroxyproline-rich glycoprotein (molecular mass 120 kDa) has been purified from the styles of Nicotiana alata. An antibody, specific for the protein backbone (molecular mass 78 kDa) of the glycoprotein, was used to demonstrate that the glycoprotein is a soluble, style-specific component and that related molecules are present in the styles of other solanaceous species. Linkage analysis of the carbohydrate portion of the glycoprotein, together with antibody binding studies, indicates that the glycoprotein contains both extensin-like and arabinogalactan-protein (AGP)-like side chains. Furthermore, the AGP-like side-chains contain a style-specific epitope that is also present on AGPs from N. alata styles and glycoconjugates from the styles of other members of the Solanaceae. The abundance of this 120 kDa glycoprotein, its location in the extracellular matrix of the transmitting tract and its conservation in several species within the Solanaceae suggests a role in pistil function.

Antibodies↗
PubMed1977

Effects of aldosterone on the urinary excretion of total and non-dialyzable hydroxyproline.

In order to explore the role of mineralocorticoids on collagen metabolism, the effects of aldosterone on the urinary excretion of total and non dialyzable hydroxyproline (HYPRO) was studied in rats. The administration of aldosterone in sesame oil, 75 microgram/100 g body weight to adrenalectomized rats maintained on 1% NaCl solution as drinking fluid and 1 mg of cortisone subcutaneously daily, provoked elevation of total and non dialyzable HYPRO in urine (P less than 0.001), when compared to similarly treated adrenalectomized rats receiving sesame oil but no aldosterone. Both groups showed a normal growth curve and had similar urinary excretion of creatinine. The effects of aldosterone are opposed to the known lowering effects of glucocorticoids on HYPRO excretion and may suggest an effect of aldosterone on collagen turnover. Alternatively, aldosterone may modify the metabolism or excretion of HYPRO in an opposite manner to that of glucocorticoids.

Adrenalectomy↗
PubMed1988

Excretion of 3-methylhistidine and hydroxyproline following acute weight-training exercise.

Changes in urine excretion of 3-methylhistidine (3MH) and hydroxyproline (OHP) were investigated following a single session of weight training that produced delayed onset muscle soreness (DOMS). The subjects (n = 18) maintained meat-free diets for 6 days and collected 24-h urine volume on day 4 (PRE), day 5 (POST1), and day 6 (POST2) for analysis of 3MH, OHP, and creatinine (CRE). At the end of PRE, nine subjects (EX) performed intensive weight-training exercises. The remaining subjects (NE) served as a nonexercised group. All subjects were measured for fat free weight (FFW) and rated DOMS at the end of each urine collection period, i.e., PRE, POST1, and POST2. The results were significant DOMS ratings on POST1 and POST2 compared with PRE2 for EX only. Excretion of 3MH (x +/- SE in mumol/day) by group were, for EX, PRE 271 +/- 18, POST1 243 +/- 16, POST2 259 +/- 23; for NE, PRE 203 +/- 23, POST1 209 +/- 27, POST2 225 +/- 32. Excretion of OHP (x +/- SE in mg/day) were, for EX, PRE 30.0 +/- 5.4, POST1 32.8 +/- 6.4, POST2 29.6 +/- 6.1; for NE, PRE 22.5 +/- 5.2, POST1 21.6 +/- 6.0, POST2 22.7 +/- 6.0. Changes in urine 3MH and OHP were not statistically significant, whether analyzed in absolute terms or relative to CRE and FFW. It was concluded that the acute session of weight training which produced muscle soreness did not effect excretion of 3MH or OHP.

Adult↗
PubMed1990

Cell wall regeneration in Chlamydomonas: accumulation of mRNAs encoding cell wall hydroxyproline-rich glycoproteins.

The unicellular alga Chlamydomonas reinhardtii is surrounded by a cell wall composed entirely of hydroxyproline-rich glycoproteins (HRGPs). When the walls of vegetative cells are removed with the enzyme gamete autolysin (g-lysin), they regenerate a matrix within 3-4 hr. In vitro translation of mRNAs isolated from g-lysin-treated cells showed significant increases and decreases in abundance of several mRNAs encoding proline-rich polypeptides. Because the population of up-regulated mRNAs is likely to include species encoding cell wall components, expression of genes for two outer wall HRGPs (GP1 and GP2) was analyzed during wall regeneration by using cDNAs isolated from a C. reinhardtii lambda gt11 library. Transcripts encoding GP1 and GP2 were elevated severalfold within the first hour or regeneration, suggesting that upregulation of HRGP mRNAs is a primary response to cell wall removal by g-lysin. Cell wall regeneration in Chlamydomonas provides an accessible system to study HRGP gene expression during matrix development.

Amino Acid Sequence↗
PubMed1999

Synthetic genes for glycoprotein design and the elucidation of hydroxyproline-O-glycosylation codes.

Design of hydroxyproline (Hyp)-rich glycoproteins (HRGPs) offers an approach for the structural and functional analysis of these wall components, which are broadly implicated in plant growth and development. HRGPs consist of multiple small repetitive "glycomodules" extensively O-glycosylated through the Hyp residues. The patterns of Hyp-O-glycosylation are putatively coded by the primary sequence as described by the Hyp contiguity hypothesis, which predicts contiguous Hyp residues to be attachment sites of small arabinooligosaccharides (1-5 Ara residues/Hyp); while clustered, noncontiguous Hyp residues are sites of arabinogalactan polysaccharide attachment. As a test, we designed two simple HRGPs as fusion proteins with green fluorescent protein. The first was a repetitive Ser-Hyp motif that encoded only clustered noncontiguous Hyp residues, predicted polysaccharide addition sites. The resulting glycoprotein had arabinogalactan polysaccharide O-linked to all Hyp residues. The second construct, based on the consensus sequence of a gum arabic HRGP, contained both arabinogalactan and arabinooligosaccharide addition sites and, as predicted, gave a product that contained both saccharide types. These results identify an O-glycosylation code of plants.

Amino Acid Motifs↗
PubMed2000

Glycosylation/Hydroxylation-induced stabilization of the collagen triple helix. 4-trans-hydroxyproline in the Xaa position can stabilize the triple helix.

We have shown recently that glycosylation of threonine in the peptide Ac-(Gly-Pro-Thr)(10)-NH(2) with beta-d-galactose induces the formation of a collagen triple helix, whereas the nonglycosylated peptide does not. In this report, we present evidence that a collagen triple helix can also be formed in the Ac-(Gly-Pro-Thr)(10)-NH(2) peptide, if the proline (Pro) in the Xaa position is replaced with 4-trans-hydroxyproline (Hyp). Furthermore, replacement of Pro with Hyp in the sequence Ac-(Gly-Pro-Thr(beta-d-Gal))(10)-NH(2) increases the T(m) of the triple helix by 15.7 degrees C. It is generally believed that Hyp in the Xaa position destabilizes the triple helix because (Pro-Pro-Gly)(10) and (Pro-Hyp-Gly)(10) form stable triple helices but the peptide (Hyp-Pro-Gly)(10) does not. Our data suggest that the destabilizing effect of Hyp relative to Pro in the Xaa position is only true in the case of (Hyp-Pro-Gly)(10). Increasing concentrations of galactose in the solvent stabilize the triple helix of Ac-(Gly-Hyp-Thr)(10)-NH(2) but to a much lesser extent than that achieved by covalently linked galactose. The data explain some of the forces governing the stability of the annelid/vestimentiferan cuticle collagens.

Amino Acid Sequence↗
PubMed2002

Co-translational incorporation of trans-4-hydroxyproline into recombinant proteins in bacteria.

Trans-4-hydroxyproline (Hyp) in eukaryotic proteins arises from post-translational modification of proline residues. Because the modification enzyme is not present in prokaryotes, no natural means exists to incorporate Hyp into proteins synthesized in Escherichia coli. We show here that under appropriate culture conditions Hyp is incorporated co-translationally directly at proline codons in genes expressed in E. coli. The use of Hyp by E. coli protein synthesis machinery under typical culture conditions is not adequate to support protein synthesis; however, intracellular concentrations of Hyp sufficient to compensate for the poor use are achieved in media with hyperosmotic sodium chloride concentrations. Hyp incorporation was demonstrated in several recombinant proteins including human Type I collagen polypeptides. A fragment of the human collagen Type I (alpha1) polypeptide with global Hyp for Pro substitution forms a triple helix. Our results demonstrate a remarkable pliancy in the biosynthetic apparatus of bacteria that may be used more generally to incorporate novel amino acids into recombinant proteins.

Amino Acid Sequence↗
PubMed2004

Structure of a hydroxyproline (Hyp)-arabinogalactan polysaccharide from repetitive Ala-Hyp expressed in transgenic Nicotiana tabacum.

A synthetic gene encoding the fusion protein (Ala-Hyp)(51)-enhanced green fluorescent protein expressed in Nicotiana tabacum cells produced a fusion glycoprotein with all proline residues hydroxylated and substituted with an arabinogalactan polysaccharide. Alkaline hydrolysis of the fusion glycoprotein yielded a population of hydroxyproline (Hyp)-arabinogalactan polysaccharides ranging in size from 13 to 26 saccharide residues/Hyp, with a median size of 15-17 residues. We isolated a 15-residue Hyp-arabinogalactan for structure determination by sugar analyses and one- and two-dimensional nuclear magnetic resonance techniques that provided the assignment of proton and carbon signals of a small polysaccharide O-linked to the hydroxyl group of Hyp. The polysaccharide consisted of a 1,3-linked beta-D-Galp backbone with a single 1,6-linked beta-D-Galp "kink." The backbone had two side chains of Galp substituted at position 3 with an arabinose di- or trisaccharide and at position 6 with glucuronic acid or rhamnosyl glucuronic acid. Energy-minimized space-filling molecular models showed hydrogen bonding within polysaccharides attached to repetitive Ala-Hyp and also between polysaccharides and the peptide backbone. Polysaccharides distorted the peptide Ramachandran angles consistent with the circular dichroic spectra of isolated (Ala-Hyp)(51) and its reversion to a polyproline II-like helix after deglycosylation. This first complete structure of a Hyp-arabinogalactan polysaccharide shows that computer-based molecular modeling of Hyp-rich glycoproteins is now feasible and supports the suggestion that small repetitive subunits comprise larger arabinogalactan polysaccharides.

Carbon↗
PubMed2006

Structural basis for the platelet-collagen interaction: the smallest motif within collagen that recognizes and activates platelet Glycoprotein VI contains two glycine-proline-hydroxyproline triplets.

Collagen-related peptide is a selective agonist for the platelet collagen receptor Glycoprotein VI. The triple helical peptide contains ten GPO triplets/strand (single letter amino acid nomenclature, where O is hydroxyproline) and so over-represents GPO compared with native collagen sequence. To investigate the ability of Glycoprotein VI to recognize GPO triplets in a setting more representative of the collagens, we synthesized a set of triple helical peptides containing fewer GPO triplets, varying their number and spacing within an inert (GPP)n backbone. The adhesion of recombinant human Glycoprotein VI ectodo-main, like that of human platelets, to these peptides increased with their GPO content, and platelet adhesion was abolished by the specific anti-Glycoprotein VI-blocking antibody, 10B12. Platelet aggregation and protein tyrosine phosphorylation were induced only by cross-linked peptides and only those that contained two or more GPO triplets. Such peptides were less potent than cross-linked collagen-related peptide. Our data suggest that both the sequences GPOGPO and GPO.........GPO represent functional Glycoprotein VI recognition motifs within collagen. Furthermore, we propose that the (GPO)4 motif can support simultaneous binding of two glycoprotein VI molecules, in either a parallel or anti-parallel stacking arrangement, which could play an important role in activation of signaling.

Binding Sites↗
PubMed2002

Hydroxyproline distribution in the plasma of various mammals.

We have investigated the presence of total, free, protein-bound and peptide-bound hydroxyproline (Hyp) in the plasma of different mammals viz., camel, bovine, sheep, human, rabbit and rat. Total Hyp was significantly highest in human followed by rabbit, rat, bovine, sheep and camel (P<0.001). Free Hyp was significantly highest in human followed by rabbit, rat, camel, bovine and sheep (P<0.001). However, the protein-bound Hyp content was significantly highest in rat followed by bovine, human, camel, rabbit and sheep (P<0.001). Peptide-bound Hyp was significantly highest in human plasma followed by sheep and rabbit (P<0.001). No peptide-bound Hyp was detected in the plasma of camel, bovine or rat. In the human plasma, peptide-bound Hyp constituted 60% of the total plasma Hyp, followed by protein-bound Hyp, which was 35% of the total, Hyp and free Hyp, which was 15% of the total plasma Hyp. In the sheep plasma peptide-bound Hyp constituted about 50% of total Hyp followed by protein-bound (40% of the total Hyp) and free Hyp, which formed 10% of total Hyp. In the rabbit plasma protein-bound Hyp constituted 50% of the total Hyp fraction, followed by peptide-bound and free, which constituted about 30 and 20%, respectively, of the total Hyp fraction of the plasma. Peptide-bound Hyp formed 92, 84 and 82% of the total plasma Hyp in rat, camel and bovine, respectively. Free Hyp constituted about 8% of the total plasma Hyp in rat and 18% of total Hyp in bovine and camel, respectively. The causes of the significant variations in different collagen structure and composition with respect to the different species examined are not known, however, these variations may results from differences in turn-over rate of Hyp in those species.

Animals↗
PubMed1996

Sodium excretion in relation to calcium and hydroxyproline excretion in a healthy Japanese population.

To evaluate whether habitual excess sodium intake is a significant risk factor for calcium loss, we studied the relation between calcium excretion and sodium excretion in 410 male and 476 female Japanese aged 20-79 y. They were apparently healthy, free-living, and consuming diets of their own choosing. We divided the subjects into two groups: 20-49 y olds and 50-79 y olds. In each group, we observed significant positive correlation between daily calcium excretion and daily sodium excretion in both sexes. Multivariate analyses revealed that in each age group the relation was still significant after sex, age, body weight, and protein, calcium, and phosphorus intakes were adjusted for. The increases in urinary calcium excretion were estimated to be approximately 0.6 and 1.0 mmol for a 100-mmol increment in urinary sodium excretion for the 20-49 y olds and 50-79-y olds, respectively. We also observed significant positive correlations between daily hydroxyproline excretion and daily sodium excretion in both sexes for both age groups. The relation was still significant after sex, age, body weight, and protein intake from meat and fish were adjusted for. The results suggest that individuals with high sodium intake may lose more calcium in their urine than those with low sodium intake.

Adult↗
PubMed1977

Measurement of urinary and serous-fluid glycosaminoglycans and urinary hydroxyproline.

Although analytic measurements of connective tissue components in biological fluids would frequently be useful in diagnosis and/or management of many inflammatory, neoplastic and metabolic diseases, such information is often unavailable due to the methodologic problems posed by these natural products. This report outlines relatively simple procedures leading to the colorimetric measurement of glycosaminoglycans in urine and other body fluids and to measurement of hydroxyproline in urine. Normal values and potential applications are presented.

Ascitic Fluid↗
PubMed1981

Effects of hydroxyproline and vitamin B-6 on oxalate synthesis in rats.

Relationships among dietary hydroxyproline (HP), vitamin B-6 and endogenous oxalate formation have been studied. In the absence of HP, urinary oxalate excretion was greatest among rats fed vitamin B-6-deficient diets. Supplementation of rat diets with 5.2% HP markedly increased the oxalate excretion of rats fed 0, 0.2 or 10 mg of vitamin B-6 per 100 g of diet, the increases being 2-, 19- and 15-fold respectively. The metabolism of several 14C-labeled oxalate precursors was altered in vitamin B-6-deficient rats. The feeding of HP and different levels of vitamin B-6 also altered their metabolism. The feeding of HP to vitamin B-6-deficient rats resulted in a decrease in the amount of 14C-oxalate formed from injected 14C-labeled glycine, glycolate or glyoxylate. In contrast, HP feeding to rats given 0.2 mg of vitamin B-6 per 100 g, resulted in a marked increase in oxalate formation from injected 14C-glycolate, as well as a decrease in respiratory 14CO2 from injected 14C-labeled glycolate and glyoxylate. HP feedings did not significantly alter the metabolism of these two injected compounds to oxalate or CO2 among rats fed the higher level of vitamin B-6, although some elevation of oxalate formation from glycolate was noted. HP feeding reduced the growth rates of all the rats, but growth depression was greatest in the vitamin B-6-deficient group.

Animals↗
PubMed2002

Art v 1, the major allergen of mugwort pollen, is a modular glycoprotein with a defensin-like and a hydroxyproline-rich domain.

In late summer, pollen grains originating from Compositae weeds (e.g., mugwort, ragweed) are a major source of allergens worldwide. Here, we report the isolation of a cDNA clone coding for Art v 1, the major allergen of mugwort pollen. Sequence analysis showed that Art v 1 is a secreted allergen with an N-terminal cysteine-rich domain homologous to plant defensins and a C-terminal proline-rich region containing several (Ser/Ala)(Pro)2-4 repeats. Structural analysis showed that some of the proline residues in the C-terminal domain of Art v 1 are posttranslationally modified by hydroxylation and O-glycosylation. The O-glycans are composed of 3 galactoses and 9-16 arabinoses linked to a hydroxyproline and represent a new type of plant O-glycan. A 3-D structural model of Art v 1 was generated showing a characteristic "head and tail" structure. Evaluation of the antibody binding properties of natural and recombinant Art v 1 produced in Escherichia coli revealed the involvement of the defensin fold and posttranslational modifications in the formation of epitopes recognized by IgE antibodies from allergic patients. However, posttranslational modifications did not influence T-cell recognition. Thus, recombinant nonglycosylated Art v 1 is a good starting template for engineering hypoallergenic vaccines for weed-pollen therapy.

Allergens↗
PubMed1993

Posttranslational processing of a new class of hydroxyproline-containing proteins. Prolyl hydroxylation and C-terminal cleavage of tobacco (Nicotiana tabacum) vacuolar chitinase.

The fungicidal class I chitinases (EC 3.2.1.14) are believed to be important in defending plants against microbial pathogens. The vacuolar isoforms of tobacco (Nicotiana tabacum), chitinases A and B, are the first examples of a new type of hydroxyproline-containing protein with intracellular location, enzymic activity, and a small number of hydroxyprolyl residues restricted to a single, short peptide sequence. We have investigated the posttranslational processing and intracellular transport of transgene-encoded chitinase A in callus cultures of Nicotiana tabacum L. cv Havana 425 and leaves of Nicotiana sylvestris Spegazzini and Comes. Pulse-chase experiments and cell fractionation show that chitinase A is processed in two distinct steps. In the first step, the nascent protein undergoes an increase in apparent M(r) of approximately 1500 detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Experiments with the inhibitor of prolyl hydroxylation, alpha,alpha'-dipyridyl, and pulse-chase labeling of cells expressing recombinant forms of chitinase A indicate that the anomalous increase in M(r) is due to hydroxylation of prolyl residues. This step occurs in the endomembrane system before sorting for secretion and vacuolar transport and does not appear to be required for correct targeting of chitinase A to the vacuole. The second step is a proteolytic cleavage. Sequencing of tryptic peptides of the mature proteins indicates that during processing essentially all molecules of chitinase A and B lose a C-terminal heptapeptide, which has been shown to be a vacuolar targeting signal. This appears to occur primarily in the endomembrane system late in intracellular transport. A model for the posttranslational modification of chitinase A is proposed.

Amino Acid Sequence↗
PubMed2006

Characterization of synthetic hydroxyproline-rich proteoglycans with arabinogalactan protein and extensin motifs in Arabidopsis.

A series of gene constructs encoding synthetic glycomodule peptides with N-terminal signal sequences and C-terminal green fluorescent proteins were expressed in transgenic Arabidopsis (Arabidopsis thaliana) under the control of the 35S promoter. The synthetic glycomodule peptides were composed of repetitive proline-containing motifs that have been previously found to be substrates for prolyl hydroxylases and subsequent O-glycosylation of the hydroxyproline residues. All of the constructs were secreted in aerial tissues, but not in roots. The amount of hydroxylation and glycosylation of the various constructs varied depending on the tissue. Also, accumulation of the proteins exhibited a high degree of cell-type specificity within various tissues due to posttranscriptional effects. The observations reveal a high level of complexity in the synthesis, secretion, and turnover of the glycoproteins.

Amino Acid Motifs↗
PubMed1990

Expression of a maize cell wall hydroxyproline-rich glycoprotein gene in early leaf and root vascular differentiation.

The spatial pattern of expression for a maize gene encoding a hydroxyproline-rich glycoprotein (HRGP) was determined by in situ hybridization. During normal development of roots and leaves, the expression of the gene was transient and particularly high in regions initiating vascular elements and associated sclerenchyma. Its expression was also associated with the differentiation of vascular elements in a variety of other tissues. The gene encoded an HRGP that had been extracted from the cell walls of maize suspension culture cells and several other embryonic and post-embryonic tissues. The gene was present in one or two copies in different varieties of maize and in the related monocots teosinte and sorghum. A single gene was cloned from maize using a previously characterized HRGP cDNA clone [Stiefel et al. (1988). Plant Mol. Biol. 11, 483-493]. In addition to the coding sequences for the HRGP and an N-terminal signal sequence, the gene contained a single intron in the nontranslated 3' end.

Amino Acid Sequence↗
PubMed1977

Bone, calcium, and hydroxyproline metabolism in hyperparathyroidism and after removal of parathyroid adenoma.

Several laboratory parameters have been followed before and after surgery in a 69-year-old woman with parathyroid adenoma and severe skeletal involvement. High preoperative levels of immunoreactive parathyroid hormone rapidly decreased postoperatively, accompanied by a similar fall in the peptide-bound hydroxyproline (HP) excretion in the urine. Renal clearance of free HP was high both pre- and postoperatively, probably because of renal damage associated with the disease. The high serum alkaline phosphatase levels increased slightly after the operation. The patient developed severe postoperative hypocalcaemia, and prolonged calcium supplement therapy was necessary. The results imply a clear correlation between the changes in Ca homeostasis and the breakdown rate of bone collagenous matrix. Postoperative hypocalcaemia was mainly due to the rapid change in the rates of bone formation and destruction.

Adenoma↗