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The Journal of Biological Chemistry Jan 1961
Topics: Collagen; Hydroxyproline; Proline
PubMed: 13712333
DOI: No ID Found -
The Journal of General Virology Jan 2014Human immunodeficiency virus type 2 (HIV-2) carries an accessory protein Vpx that is important for viral replication in natural target cells. In its C-terminal region,...
Human immunodeficiency virus type 2 (HIV-2) carries an accessory protein Vpx that is important for viral replication in natural target cells. In its C-terminal region, there is a highly conserved poly-proline motif (PPM) consisting of seven consecutive prolines, encoded in a poly-pyrimidine tract. We have previously shown that PPM is critical for Vpx expression and viral infectivity. To elucidate the molecular basis underlying this observation, we analysed the expression of Vpx proteins with various PPM mutations by in vivo and in vitro systems. We found that the number and position of consecutive prolines in PPM are important for Vpx expression, and demonstrated that PPM is essential for efficient Vpx translation. Furthermore, mutational analysis to synonymously disrupt the poly-pyrimidine tract suggested that the context of PPM amino acid sequences is required for efficient translation of Vpx. We similarly analysed HIV-1 and HIV-2 Vpr proteins structurally related to HIV-2 Vpx. Expression level of the two Vpr proteins lacking PPM was shown to be much lower relative to that of Vpx, and not meaningfully enhanced by introduction of PPM at the C terminus. Finally, we examined the Vpx of simian immunodeficiency virus from rhesus monkeys (SIVmac), which also has seven consecutive prolines, for PPM-dependent expression. A multi-substitution mutation in the PPM markedly reduced the expression level of SIVmac Vpx. Taken together, it can be concluded that the notable PPM sequence enhances the expression of Vpx proteins from viruses of the HIV-2/SIVmac group at the translational level.
Topics: Amino Acid Motifs; Amino Acid Sequence; Base Sequence; Cell Line; Gene Expression Regulation, Viral; HIV Infections; HIV-2; Humans; Molecular Sequence Data; Proline; Protein Biosynthesis; vpr Gene Products, Human Immunodeficiency Virus
PubMed: 24114794
DOI: 10.1099/vir.0.057364-0 -
European Journal of Medicinal Chemistry Jun 2018Thousands of death in Africa and other developing nations are still attributed to trypanosomiasis. Excessive sleep has been associated with increased inflammation. We...
Thousands of death in Africa and other developing nations are still attributed to trypanosomiasis. Excessive sleep has been associated with increased inflammation. We report herein, the synthesis, antitrypanosomal and anti-inflammatory activities of eight new carboxamide derivatives bearing substituted benzenesulfonamides. The base promoted reactions of l-proline and L-4-hydroxyproline with substituted benzenesulfonyl chlorides gave the benzenesulfonamides (11a-h) in excellent yields. Boric acid mediated amidation of the benzenesulfonamides (11a-h) and p-aminobenzoic acid (12) gave the new carboxamides (13a-h) in excellent yields. The new carboxamides were tested for their antitrypanosomal and anti-inflammatory activities against Trypanosome brucei gambiense and inhibition of carrageenan-induced rat paw edema. Compound 13f was the most potent antitrypanosomal agent with an IC value of 2 nM as against 5 nM for melarsoprol; whereas compound 13a was the most potent anti-inflammatory agent with percentage inhibition of carrageenan-induced rat paw edema of 58, 60, 67 and 84% after 0.5 h, 1 h, 2 h and 3 h administration respectively. The structure-activity relationship study revealed that substitution at the para position in the benzenesulfonamide ring increased both the antitrypanosomal and anti-inflammatory activities. The 4-hydroxyprolines (13a-d) showed higher anti-inflammatory activity than the prolines (13e-h). In contrast, the prolines (13e-h) had higher antitrypanosomal activities than the 4-hydroxyprolines. The link between excessive sleep and inflammation makes the report of this class of compounds possessing both antitrypanosomal and anti-inflammatory activity worthwhile. The pharmacokinetic studies showed that the compounds would not pose oral bioavailability, transport and permeability problems.
Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Antiprotozoal Agents; Carrageenan; Dose-Response Relationship, Drug; Edema; Male; Mice; Molecular Structure; Parasitic Sensitivity Tests; Proline; Rats; Structure-Activity Relationship; Sulfonamides; Trypanosoma brucei gambiense; Benzenesulfonamides
PubMed: 29778893
DOI: 10.1016/j.ejmech.2018.05.017 -
Protein Science : a Publication of the... Nov 2000The DNA-binding domain of the yeast heat shock transcription factor (HSF) contains a strictly conserved proline that is at the center of a kink. To define the role of...
The DNA-binding domain of the yeast heat shock transcription factor (HSF) contains a strictly conserved proline that is at the center of a kink. To define the role of this conserved proline-centered kink, we replaced the proline with a number of other residues. These substitutions did not diminish the ability of the full-length protein to support growth of yeast or to activate transcription, suggesting that the proline at the center of the kink is not conserved for function. The stability of the isolated mutant DNA-binding domains was unaltered from the wild-type, so the proline is not conserved to maintain the stability of the protein. The crystal structures of two of the mutant DNA-binding domains revealed that the helices in the mutant proteins were still kinked after substitution of the proline, suggesting that the proline does not cause the alpha-helical kink. So why are prolines conserved in this and the majority of other kinked alpha-helices if not for structure, function, or stability? The mutant DNA-binding domains are less soluble than wild-type when overexpressed. In addition, the folding kinetics, as measured by stopped-flow fluorescence, is faster for the mutant proteins. These two results support the premise that the presence of the proline is critical for the folding pathway of HSF's DNA-binding domain. The finding may also be more general and explain why kinked helices maintain their prolines.
Topics: Amino Acid Sequence; Circular Dichroism; Crystallography, X-Ray; DNA; Electrons; Kinetics; Kluyveromyces; Models, Molecular; Molecular Sequence Data; Mutagenesis; Proline; Protein Conformation; Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Software; Spectrometry, Fluorescence; Temperature; Transcription, Genetic; Tryptophan; Yeasts; beta-Galactosidase
PubMed: 11305238
DOI: 10.1110/ps.9.11.2128 -
Journal of the American Chemical Society Apr 2020Proline is found in a cis conformation in proteins more often than other proteinogenic amino acids, where it influences structure and modulates function, being the focus...
Proline is found in a cis conformation in proteins more often than other proteinogenic amino acids, where it influences structure and modulates function, being the focus of several high-resolution structural studies. However, until now, technical and methodological limitations have hampered the site-specific investigation of the conformational preferences of prolines present in poly proline (poly-P) homorepeats in their protein context. Here, we apply site-specific isotopic labeling to obtain high-resolution NMR data on the cis/trans equilibrium of prolines within the poly-P repeats of huntingtin exon 1, the causative agent of Huntington's disease. Screening prolines in different positions in long (poly-P) and short (poly-P) poly-P tracts, we found that, while the first proline of poly-P tracts adopts similar levels of cis conformation as isolated prolines, a length-dependent reduced abundance of cis conformers is observed for terminal prolines. Interestingly, the cis isomer could not be detected in inner prolines, in line with percentages derived from a large database of proline-centered tripeptides extracted from crystallographic structures. These results suggest a strong cooperative effect within poly-Ps that enhances their stiffness by diminishing the stability of the cis conformation. This rigidity is key to rationalizing the protection toward aggregation that the poly-P tract confers to huntingtin. Furthermore, the study provides new avenues to probe the structural properties of poly-P tracts in protein design as scaffolds or nanoscale rulers.
Topics: Amino Acid Sequence; Humans; Proline; Protein Conformation
PubMed: 32266815
DOI: 10.1021/jacs.0c02263 -
Journal of Magnetic Resonance (San... Jul 2022T cells engineered to express artificial chimeric antigen receptors (CARs) that selectively target tumor-specific antigens or deleterious cell types offer transformative...
T cells engineered to express artificial chimeric antigen receptors (CARs) that selectively target tumor-specific antigens or deleterious cell types offer transformative therapeutic possibilities. CARs contain an N-terminal extracellular antigen recognition domain, C-terminal intracellular signal transduction domains, and connecting hinge and transmembrane regions, each of which have been varied to optimize targeting and minimize toxicity. We find that a CD22-targeting CAR harboring a CD8α hinge (H) exhibits greater cytotoxicity against a low antigen density CD22 leukemia as compared to an equivalent CAR with a CD28 H. We therefore studied the biophysical and dynamic properties of the CD8α H by nuclear magnetic resonance (NMR) spectroscopy. We find that a large region of the CD8α H undergoes dynamic chemical exchange between distinct and observable states. This exchanging region contains proline residues dispersed throughout the sequence that undergo cis-trans isomerization. Up to four signals of differing intensity are observed, with the most abundantly populated being intrinsically disordered and with all prolines in the trans isomerization state. The lesser populated states all contain cis prolines and evidence of local structural motifs. Altogether, our data suggest that the CD8α H lacks long-range structural order but has local structural motifs that transiently exchange with a dominant disordered state. We propose that structural plasticity and local structural motifs promoted by cis proline states within the CD8α H are important for relaying and amplifying antigen-binding effects to the transmembrane and signal transduction domains.
Topics: Amino Acid Sequence; Isomerism; Magnetic Resonance Spectroscopy; Proline
PubMed: 35617919
DOI: 10.1016/j.jmr.2022.107234 -
The Journal of Physical Chemistry. B Jun 2019Due to its unique structure, proline plays important structural and functional roles in proteins. However, this special amino acid lacks an adequate vibrational mode...
Due to its unique structure, proline plays important structural and functional roles in proteins. However, this special amino acid lacks an adequate vibrational mode that can be exploited to probe its local electrostatic and hydration status via infrared spectroscopy. Herein, we show that the C═O stretching vibration of a proline derivative, 4-oxoproline, is sensitive to local environment and hence can be used as a site-specific infrared probe. We further validate this notion by applying this unnatural amino acid to assess the thermodynamics of proline cis-trans isomerization in a peptide environment and examine the amino acid dimer formation in concentrated proline and glycine solutions.
Topics: Dimerization; Isomerism; Molecular Structure; Proline; Quantum Theory; Spectroscopy, Fourier Transform Infrared; Static Electricity; Thermodynamics; Water
PubMed: 31135160
DOI: 10.1021/acs.jpcb.9b03766 -
Metabolism: Clinical and Experimental Nov 1987A quantitative exploration of the regulation of plasma proline concentration, proline oxidation, and proline endogenous biosynthesis was undertaken utilizing a...
A quantitative exploration of the regulation of plasma proline concentration, proline oxidation, and proline endogenous biosynthesis was undertaken utilizing a 360-minute primed continuous infusion of L-[1-13C]proline and L-[methyl-2H3]leucine in healthy, postabsorptive young men. The response of proline metabolism to the intravenous administration of two physiologic rates of L-proline, as well as the withdrawal of an L-proline infusion, were examined. The administration of L-proline at 20 mumol.kg-1.h-1 after an overnight fast resulted in a higher steady state plasma proline concentration, attained within 100 minutes, and this was associated with an increase in proline oxidation, from a baseline value of 10.9 to 16.1 mumol.kg-1.h-1 (P less than .01). Additionally, there was a decrease in proline endogenous synthesis from 15.8 (baseline) to 5.3 mumol.kg-1.h-1 (P less than .01). Administration of L-proline at 40 mumol.kg-1.h-1 after an overnight fast resulted again in a higher plasma steady state proline concentration, attained within 100 minutes and with an associated increase in proline oxidation from 13.1 to 20.0 mumol.kg-1.h-1 (P less than .01) and with a decrease in proline endogenous synthesis from 12.2 to -0.6 mumol.kg-1.h-1 (P less than 0.01). The withdrawal of L-proline after a 20 mumol.kg-1.h-1 infusion resulted in a lower plasma steady state proline level and this was accompanied by a decrease in proline oxidation from 21.2 to 18.2 mumol.kg-1.h-1 (P less than .05) and an increase in endogenous synthesis from 22.2 to 29.7 mumol.kg-1.h-1 (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Adult; Carbon Radioisotopes; Dietary Proteins; Eggs; Homeostasis; Humans; Infusions, Intravenous; Kinetics; Male; Proline
PubMed: 3670073
DOI: 10.1016/0026-0495(87)90023-0 -
Acta Crystallographica. Section D,... May 2020L-Hydroxyproline (L-Hyp) is a nonstandard amino acid that is present in certain proteins, in some antibiotics and in the cell-wall components of plants. L-Hyp is the...
L-Hydroxyproline (L-Hyp) is a nonstandard amino acid that is present in certain proteins, in some antibiotics and in the cell-wall components of plants. L-Hyp is the product of the post-translational modification of protein prolines by prolyl hydroxylase enzymes, and the isomers trans-3-hydroxy-L-proline (T3LHyp) and trans-4-hydroxy-L-proline (T4LHyp) are major components of mammalian collagen. T4LHyp follows two distinct degradation pathways in bacteria and mammals, while T3LHyp is metabolized by a two-step metabolic pathway that is conserved in bacteria and mammals, which involves a T3LHyp dehydratase and a Δ-pyrroline-2-carboxylate (Pyr2C) reductase. In order to shed light on the structure and catalysis of the enzyme involved in the second step of the T3LHyp degradation pathway, the crystal structure of Pyr2C reductase from the archaeon Thermococcus litoralis DSM 5473 complexed with NADH and L-proline is presented. The model allows the mapping of the residues involved in cofactor and product binding and represents a valid model for rationalizing the catalysis of Pyr2C reductases.
Topics: Archaeal Proteins; NAD; Proline; Protein Binding; Protein Conformation; Pyrroles; Pyrroline Carboxylate Reductases; Thermococcus
PubMed: 32355045
DOI: 10.1107/S2059798320004866 -
Journal of the American Chemical Society Mar 2018Proline is prevalent in intrinsically disordered proteins (IDPs). NMR assignment of proline-rich IDPs is a challenge due to low dispersion of chemical shifts. We propose...
Proline is prevalent in intrinsically disordered proteins (IDPs). NMR assignment of proline-rich IDPs is a challenge due to low dispersion of chemical shifts. We propose here new sensitivity-enhanced 4D NMR experiments that correlate two pairs of amide resonances that are either consecutive (NH , NH ) or flanking a proline at position i-1 (NH , NH ). The maximum 2-fold enhancement of sensitivity is achieved by employing two coherence order-selective (COS) transfers incorporated unconventionally into the pulse sequence. Each COS transfer confers an enhancement over amplitude-modulated transfer by a factor of √2 specifically when transverse relaxation is slow. The experiments connect amide resonances over a long fragment of sequence interspersed with proline. When this method was applied to the proline-rich region of B cell adaptor protein SLP-65 (pH 6.0) and α-synuclein (pH 7.4), which contain a total of 52 and 5 prolines, respectively, 99% and 92% of their nonprolyl amide resonances have been successfully assigned, demonstrating its robustness to address the assignment problem in large proline-rich IDPs.
Topics: Adaptor Proteins, Signal Transducing; Amides; Humans; Nuclear Magnetic Resonance, Biomolecular; Proline; alpha-Synuclein
PubMed: 29489342
DOI: 10.1021/jacs.8b00215