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Plant Biology (Stuttgart, Germany) Apr 2023Climate change and abiotic stress factors are key players in crop losses worldwide. Among which, extreme temperatures (heat and cold) disturb plant growth and... (Review)
Review
Climate change and abiotic stress factors are key players in crop losses worldwide. Among which, extreme temperatures (heat and cold) disturb plant growth and development, reduce productivity and, in severe cases, lead to plant death. Plants have developed numerous strategies to mitigate the detrimental impact of temperature stress. Exposure to stress leads to the accumulation of various metabolites, e.g. sugars, sugar alcohols, organic acids and amino acids. Plants accumulate the amino acid 'proline' in response to several abiotic stresses, including temperature stress. Proline abundance may result from de novo synthesis, hydrolysis of proteins, reduced utilization or degradation. Proline also leads to stress tolerance by maintaining the osmotic balance (still controversial), cell turgidity and indirectly modulating metabolism of reactive oxygen species. Furthermore, the crosstalk of proline with other osmoprotectants and signalling molecules, e.g. glycine betaine, abscisic acid, nitric oxide, hydrogen sulfide, soluble sugars, helps to strengthen protective mechanisms in stressful environments. Development of less temperature-responsive cultivars can be achieved by manipulating the biosynthesis of proline through genetic engineering. This review presents an overview of plant responses to extreme temperatures and an outline of proline metabolism under such temperatures. The exogenous application of proline as a protective molecule under extreme temperatures is also presented. Proline crosstalk and interaction with other molecules is also discussed. Finally, the potential of genetic engineering of proline-related genes is explained to develop 'temperature-smart' plants. In short, exogenous application of proline and genetic engineering of proline genes promise ways forward for developing 'temperature-smart' future crop plants.
Topics: Temperature; Hot Temperature; Proline; Plants; Stress, Physiological; Sugars
PubMed: 36748909
DOI: 10.1111/plb.13510 -
Cellular and Molecular Life Sciences :... May 2020This review is focused on recent data on the role of proline (Pro) in collagen biosynthesis and cellular metabolism. It seems obvious that one of the main substrates for... (Review)
Review
This review is focused on recent data on the role of proline (Pro) in collagen biosynthesis and cellular metabolism. It seems obvious that one of the main substrates for collagen biosynthesis Pro is required to form collagen molecule. The question raised in this review is whether the Pro for collagen biosynthesis is synthesized "de novo", comes directly from degraded proteins or it is converted from other amino acids. Recent data provided evidence that extracellular Pro (added to culture medium) had significant, but relatively little impact on collagen biosynthesis in fibroblasts (the main collagen synthesized cells) cultured in the presence of glutamine (Gln). However, extracellular Pro drastically increased collagen biosynthesis in the cells cultured in Gln-free medium. It suggests that Pro availability determines the rate of collagen biosynthesis and demand for Pro in fibroblasts is predominantly met by conversion from Gln. The potential mechanism of this process as well as possible implication of this knowledge in pharmacotherapy of connective tissue diseases is discussed in this review.
Topics: Collagen; Connective Tissue Diseases; Fibroblasts; Glutamine; Humans; Proline; Skin
PubMed: 31740988
DOI: 10.1007/s00018-019-03363-3 -
Molecular Metabolism Jul 2023Brown adipose tissue (BAT) plays a crucial role in regulating non-shivering thermogenesis under cold exposure. Proline hydroxylases (PHDs) were found to be involved in...
OBJECTIVE
Brown adipose tissue (BAT) plays a crucial role in regulating non-shivering thermogenesis under cold exposure. Proline hydroxylases (PHDs) were found to be involved in adipocyte differentiation and lipid deposition. However, the effects of PHDs on regulatory mechanisms of BAT thermogenesis are not fully understood.
METHODS
We detected the expression of PHDs in different adipose tissues by using immunoblotting and real-time PCR. Further, immunoblotting, real-time PCR, and immunostaining were performed to determine the correlation between proline hydroxylase 2 (PHD2) and UCP1 expression. Inhibitor of PHDs and PHD2-sgRNA viruses were used to construct the PHD2-deficiency model in vivo and in vitro to investigate the impacts of PHD2 on BAT thermogenesis. Afterward, the interaction between UCP1 and PHD2 and the hydroxylation modification level of UCP1 were verified by Co-IP assays and immunoblotting. Finally, the effect of specific proline hydroxylation on the expression/activity of UCP1 was further confirmed by site-directed mutation of UCP1 and mass spectrometry analysis.
RESULTS
PHD2, but not PHD1 and PHD3, was highly enriched in BAT, colocalized, and positively correlated with UCP1. Inhibition or knockdown of PHD2 significantly suppressed BAT thermogenesis under cold exposure and aggravated obesity of mice fed HFD. Mechanistically, mitochondrial PHD2 bound to UCP1 and regulated the hydroxylation level of UCP1, which was enhanced by thermogenic activation and attenuated by PHD2 knockdown. Furthermore, PHD2-dependent hydroxylation of UCP1 promoted the expression and stability of UCP1 protein. Mutation of the specific prolines (Pro-33, 133, and 232) in UCP1 significantly mitigated the PHD2-elevated UCP1 hydroxylation level and reversed the PHD2-increased UCP1 stability.
CONCLUSIONS
This study suggested an important role for PHD2 in BAT thermogenesis regulation by enhancing the hydroxylation of UCP1.
Topics: Animals; Mice; Adipose Tissue, Brown; Hydroxylation; Obesity; Proline; Prolyl Hydroxylases; Thermogenesis
PubMed: 37279828
DOI: 10.1016/j.molmet.2023.101747 -
Laboratory Medicine Sep 2022The aim of the study was to evaluate proline metabolism in patients affected by COVID-19.
OBJECTIVE
The aim of the study was to evaluate proline metabolism in patients affected by COVID-19.
MATERIALS AND METHODS
This case-control study consisted of 116 patients with COVID-19 and 46 healthy individuals. Tests related to proline metabolism (prolidase, proline, hydroxyproline, glutamic acid, manganese) and copper and zinc tests were analyzed.
RESULTS
The levels of proline and hydroxyproline amino acids and the prolidase enzyme were found to be lower and glutamic acid was found to be higher in the COVID-19 group compared to the healthy group (P = .012, P < .001, P < .001, and P < .001, respectively). The copper/zinc ratio was higher in patients with COVID-19 than in healthy individuals (P < .001). Significant correlations were found between proline metabolism tests and inflammatory and hemostatic markers commonly used in COVID-19.
CONCLUSION
The proline metabolic pathway was affected in COVID-19. Relationships between proline pathway-related tests and inflammatory/hemostatic markers supported the roles of proline metabolism in proinflammatory and immune response processes.
Topics: COVID-19; Case-Control Studies; Copper; Dipeptidases; Glutamates; Hemostatics; Humans; Hydroxyproline; Proline; Zinc
PubMed: 35394547
DOI: 10.1093/labmed/lmac017 -
Cell Death & Disease Oct 2023Cancer stem-like cells (CSCs) contribute to cancer metastasis, drug resistance and tumor relapse, yet how amino acid metabolism promotes CSC maintenance remains...
Cancer stem-like cells (CSCs) contribute to cancer metastasis, drug resistance and tumor relapse, yet how amino acid metabolism promotes CSC maintenance remains exclusive. Here, we identify that proline synthetase PYCR1 is critical for breast cancer stemness and tumor growth. Mechanistically, PYCR1-synthesized proline activates cGMP-PKG signaling to enhance cancer stem-like traits. Importantly, cGMP-PKG signaling mediates psychological stress-induced cancer stem-like phenotypes and tumorigenesis. Ablation of PYCR1 markedly reverses psychological stress-induced proline synthesis, cGMP-PKG signaling activation and cancer progression. Clinically, PYCR1 and cGMP-PKG signaling components are highly expressed in breast tumor specimens, conferring poor survival in breast cancer patients. Targeting proline metabolism or cGMP-PKG signaling pathway provides a potential therapeutic strategy for breast patients undergoing psychological stress. Collectively, our findings unveil that PYCR1-enhanced proline synthesis displays a critical role in maintaining breast cancer stemness.
Topics: Female; Humans; Breast Neoplasms; Neoplasm Recurrence, Local; Oxidoreductases; Proline; delta-1-Pyrroline-5-Carboxylate Reductase
PubMed: 37845207
DOI: 10.1038/s41419-023-06200-5 -
Cell Host & Microbe Mar 2021Most viral vaccines are based on inducing neutralizing antibodies (NAbs) against the virus envelope or spike glycoproteins. Many viral surface proteins exist as trimers... (Review)
Review
Most viral vaccines are based on inducing neutralizing antibodies (NAbs) against the virus envelope or spike glycoproteins. Many viral surface proteins exist as trimers that transition from a pre-fusion state when key NAb epitopes are exposed to a post-fusion form in which the potential for virus-cell fusion no longer exists. For optimal vaccine performance, these viral proteins are often engineered to enhance stability and presentation of these NAb epitopes. The method involves the structure-guided introduction of proline residues at key positions that maintain the trimer in the pre-fusion configuration. We review how this technique emerged during HIV-1 Env vaccine development and its subsequent wider application to other viral vaccines including SARS-CoV-2.
Topics: Antibodies, Neutralizing; COVID-19 Vaccines; Humans; Models, Molecular; Proline; Protein Engineering; Viral Vaccines
PubMed: 33705704
DOI: 10.1016/j.chom.2021.02.002 -
Journal of Bacteriology Aug 2022Clostridioides difficile is a nosocomial pathogen that colonizes the gut and causes diarrhea, colitis, and severe inflammation. Recently, C. difficile has been shown to...
Clostridioides difficile is a nosocomial pathogen that colonizes the gut and causes diarrhea, colitis, and severe inflammation. Recently, C. difficile has been shown to use toxin-mediated inflammation to promote host collagen degradation, which releases several amino acids into the environment. Amino acids act as electron donors and acceptors in Stickland metabolism, an anaerobic process involving redox reactions between pairs of amino acids. Proline, glycine, and hydroxyproline are the three main constituents of collagen and are assumed to act as electron acceptors, but their exact effects on the growth and physiology of C. difficile are still unclear. Using three standard culture media (supplemented brain heart infusion [BHIS], tryptone-yeast [TY], and minimal medium [CDMM]) supplemented with proline, glycine, or hydroxyproline, we grew C. difficile strains R20291, JIR8094, and a panel of mutants unable to express the Stickland selenoenzymes d-proline reductase and glycine reductase. In the wild-type strains, growth yields in rich media (BHIS and TY) were higher with proline and hydroxyproline but not glycine; moreover, proline-stimulated growth yields required the activity of d-proline reductase, whereas hydroxyproline-stimulated growth yields were independent of its activity. While assumed to be a proline auxotroph, C. difficile could surprisingly grow in a defined medium (CDMM) without proline but only if d-proline reductase was absent. We believe the mere presence of this enzyme ultimately determines the organism's strict dependence on proline and likely defines the bioenergetic priorities for thriving in the host. Finally, we demonstrated that addition of proline and hydroxyproline to the culture medium could reduce toxin production but not in cells lacking selenoproteins. Stickland metabolism is a core facet of C. difficile physiology that likely plays a major role in host colonization. Here, we carefully delineate the effects of each amino acid on the growth of C. difficile with respect to the selenoenzymes d-proline reductase and glycine reductase. Moreover, we report that d-proline reductase forces C. difficile to strictly depend on proline for growth. Finally, we provide evidence that proline and hydroxyproline suppress toxin production and that selenoproteins are involved in this mechanism. Our findings highlight the significance of selenium-dependent Stickland reactions and may provide insight on what occurs during host infection, especially as it relates to the decision to colonize based on proline as a nutrient.
Topics: Amino Acid Oxidoreductases; Amino Acids; Clostridioides; Clostridioides difficile; Glycine; Humans; Hydroxyproline; Inflammation; Proline; Selenoproteins
PubMed: 35862761
DOI: 10.1128/jb.00229-22 -
Cell Death and Differentiation May 2022The p53 protein is structurally and functionally divided into five domains. The proline-rich domain is localized at amino acids 55-100. 319 missense mutations were... (Review)
Review
The p53 protein is structurally and functionally divided into five domains. The proline-rich domain is localized at amino acids 55-100. 319 missense mutations were identified solely in the proline domain from human cancers. Six hotspot mutations were identified at amino acids 72, 73, 82, 84, 89, and 98. Codon 72 contains a polymorphism that changes from proline (and African descent) to arginine (with Caucasian descent) with increasing latitudes northward and is under natural selection for pigmentation and protection from UV light exposure. Cancers associated with mutations in the proline domain were considerably enriched for melanomas and skin cancers compared to mutations in other p53 domains. These hotspot mutations are enriched at UV mutational signatures disrupting amino acid signals for binding SH-3-containing proteins important for p53 function. Among the protein-protein interaction sites identified by hotspot mutations were MDM-2, a negative regulator of p53, XAF-1, promoting p53 mediated apoptosis, and PIN-1, a proline isomerase essential for structural folding of this domain.
Topics: Genotype; Humans; Mutation, Missense; Neoplasms; Phenotype; Proline; Tumor Suppressor Protein p53
PubMed: 35383292
DOI: 10.1038/s41418-022-00980-7 -
Nature Genetics Nov 2022Histone post-translational modifications (PTMs) are important for regulating various DNA-templated processes. Here, we report the existence of a histone PTM in mammalian...
Histone post-translational modifications (PTMs) are important for regulating various DNA-templated processes. Here, we report the existence of a histone PTM in mammalian cells, namely histone H3 with hydroxylation of proline at residue 16 (H3P16oh), which is catalyzed by the proline hydroxylase EGLN2. We show that H3P16oh enhances direct binding of KDM5A to its substrate, histone H3 with trimethylation at the fourth lysine residue (H3K4me3), resulting in enhanced chromatin recruitment of KDM5A and a corresponding decrease of H3K4me3 at target genes. Genome- and transcriptome-wide analyses show that the EGLN2-KDM5A axis regulates target gene expression in mammalian cells. Specifically, our data demonstrate repression of the WNT pathway negative regulator DKK1 through the EGLN2-H3P16oh-KDM5A pathway to promote WNT/β-catenin signaling in triple-negative breast cancer (TNBC). This study characterizes a regulatory mark in the histone code and reveals a role for H3P16oh in regulating mammalian gene expression.
Topics: Animals; Histones; Methylation; Proline; Hydroxylation; Gene Expression; Mammals
PubMed: 36347944
DOI: 10.1038/s41588-022-01212-x -
Chemical Communications (Cambridge,... Dec 2022We present our design of a cross-catalytic system based on organocatalysis. The system features two organic reactions, namely a deprotection reaction of Fmoc protected...
We present our design of a cross-catalytic system based on organocatalysis. The system features two organic reactions, namely a deprotection reaction of Fmoc protected proline and a Mannich reaction between acetone and dihydroisoquinoline. The products of these two reactions, proline and a tetrahydroisoquinoline, respectively, are capable of reciprocal reaction rate enhancement. Detailed kinetic studies of the system and seeding experiments support the cross-catalytic relationship in the reaction network.
Topics: Kinetics; Catalysis; Proline; Acetone
PubMed: 36448644
DOI: 10.1039/d2cc05610k