Modular Synthesis of α‑Aryl-α-Heteroaryl α‑Amino Acid Derivatives via a Copper-Catalyzed Cross-Dehydrogenative-Coupling Reaction Using Air as the Sole Oxidant

A novel copper-catalyzed cross-dehydrogenative-coupling (CDC) process of arylglycine derivatives with N-heteroarenes for the straightforward synthesis of α-aryl-α-heteroaryl α-amino acid scaffolds has been successfully developed. This protocol exhibits a broad substrate scope with good functional group compatibility by utilizing air as the sole oxidant. The use of the reaction is also displayed through the late-stage functionalization of arylglycines bearing natural compounds or drug motifs

Quantitative Proteomics Analysis Reveals That the Nuclear Cap-Binding Complex Proteins <i>Arabidopsis</i> CBP20 and CBP80 Modulate the Salt Stress Response

The cap-binding proteins CBP20 and CBP80 have well-established roles in RNA metabolism and plant growth and development. Although these proteins are thought to be involved in the plant’s response to environmental stress, their functions in this process are unclear. Here we demonstrated that <i>Arabidopsis</i> <i>cbp20</i> and <i>cbp80</i> null mutants had abnormal leaves and flowers and exhibited increased sensitivity to salt stress. The aberrant phenotypes were more pronounced in the <i>cbp20/80</i> double mutant. Quantification by iTRAQ (isobaric tags for relative and absolute quantification) identified 77 differentially expressed proteins in the <i>cbp20</i> and <i>cbp80</i> lines compared with the wild-type Col-0 under salt stress conditions. Most of these differentially expressed proteins were synergistically expressed in <i>cbp20</i> and <i>cbp80</i>, suggesting that CBP20 and CBP80 have synergistic roles during the salt stress response. Biochemical analysis demonstrated that CBP20 and CBP80 physically interacted with each other. Further analysis revealed that CBP20/80 regulated the splicing of genes involved in proline and sugar metabolism and that the epigenetic and post-translational modifications of these genes were involved in salt stress tolerance. Our data suggest a link between CBP20/80-dependent protein ubiquitination/sumoylation and the salt stress response

Quantitative Proteomics Analysis Reveals That the Nuclear Cap-Binding Complex Proteins <i>Arabidopsis</i> CBP20 and CBP80 Modulate the Salt Stress Response

The cap-binding proteins CBP20 and CBP80 have well-established roles in RNA metabolism and plant growth and development. Although these proteins are thought to be involved in the plant’s response to environmental stress, their functions in this process are unclear. Here we demonstrated that <i>Arabidopsis</i> <i>cbp20</i> and <i>cbp80</i> null mutants had abnormal leaves and flowers and exhibited increased sensitivity to salt stress. The aberrant phenotypes were more pronounced in the <i>cbp20/80</i> double mutant. Quantification by iTRAQ (isobaric tags for relative and absolute quantification) identified 77 differentially expressed proteins in the <i>cbp20</i> and <i>cbp80</i> lines compared with the wild-type Col-0 under salt stress conditions. Most of these differentially expressed proteins were synergistically expressed in <i>cbp20</i> and <i>cbp80</i>, suggesting that CBP20 and CBP80 have synergistic roles during the salt stress response. Biochemical analysis demonstrated that CBP20 and CBP80 physically interacted with each other. Further analysis revealed that CBP20/80 regulated the splicing of genes involved in proline and sugar metabolism and that the epigenetic and post-translational modifications of these genes were involved in salt stress tolerance. Our data suggest a link between CBP20/80-dependent protein ubiquitination/sumoylation and the salt stress response

Changes of antioxidant enzyme activities in <i>K. pygmaea</i> along an elevational gradient.

<p>Error bars indicate SE. Means denoted by different letters were significantly different (<i>P</i><0.05).</p

Comparative Proteomics Analyses of <i>Kobresia pygmaea</i> Adaptation to Environment along an Elevational Gradient on the Central Tibetan Plateau

<div><p>Variations in elevation limit the growth and distribution of alpine plants because multiple environmental stresses impact plant growth, including sharp temperature shifts, strong ultraviolet radiation exposure, low oxygen content, etc. Alpine plants have developed special strategies to help survive the harsh environments of high mountains, but the internal mechanisms remain undefined. <i>Kobresia pygmaea</i>, the dominant species of alpine meadows, is widely distributed in the Southeastern Tibet Plateau, Tibet Autonomous Region, China. In this study, we mainly used comparative proteomics analyses to investigate the dynamic protein patterns for <i>K. pygmaea</i> located at four different elevations (4600, 4800, 4950 and 5100 m). A total of 58 differentially expressed proteins were successfully detected and functionally characterized. The proteins were divided into various functional categories, including material and energy metabolism, protein synthesis and degradation, redox process, defense response, photosynthesis, and protein kinase. Our study confirmed that increasing levels of antioxidant and heat shock proteins and the accumulation of primary metabolites, such as proline and abscisic acid, conferred <i>K. pygmaea</i> with tolerance to the alpine environment. In addition, the various methods <i>K. pygmaea</i> used to regulate material and energy metabolism played important roles in the development of tolerance to environmental stress. Our results also showed that the way in which <i>K. pygmaea</i> mediated stomatal characteristics and photosynthetic pigments constitutes an enhanced adaptation to alpine environmental stress. According to these findings, we concluded that <i>K. pygmaea</i> adapted to the high-elevation environment on the Tibetan Plateau by aggressively accumulating abiotic stress-related metabolites and proteins and by the various life events mediated by proteins. Based on the species'lexible physiological and biochemical processes, we surmised that environment change has only a slight impact on <i>K. pygmaea</i> except for possible impacts to populations on vulnerable edges of the species' range.</p></div

Geographical location of the sampling site.

<p><b>A</b>: The research site in the map of the eurasia continent. <b>B</b>: The geographical position of the research site on the Tibetan Plateau. <b>C</b>: Four sample sites selected at elevations of 4600, 4800, 4950 and 5100 m on the south-facing slope of the Nyainqentanglha Mountains.</p

Comparative proteomics analyses results of four samples from different elevations.

<p><b>A</b>: Functional classification of the identified proteins based on NCBI annotation. <b>B</b>: Hierarchical clustering of the identified protein expression profiles at different elevations. <b>C</b>: Venn diagram analysis of differentially expressed proteins at each higher elevations compared with 4600 m. Different colors correspond to the proteins' log-transformed fold-change ratios depicted in the bar at the bottom of the figure (B).</p

Stomatal characteristics of <i>K. pygmaea</i> from different elevations.

<p><b>A</b>: Changes in stomatal density (left) and aperture length (right) in <i>K. pygmaea</i> along an elevational gradient. <b>B</b>: Stomatal shape and size changes of <i>K. pygmaea</i> at different elevations at the same magnification. Error bars indicate SE. Means denoted by different letters are significantly different (<i>P</i><0.05) (A).</p

Identification of differentially-expressed proteins in leaves of <i>Kobresia pygmaea</i> from different altitudes as analyzed by MALDI-MS/MS.

<p><b>Acc. No.^a</b>, database accession numbers according to NCBInr; <b>Theo. </b><b><i>M</i></b><b>_w/p</b><b><i>I</i></b><b>^b</b>, theoretical <i>M</i>_w/p<i>I</i>; <b>Exp. </b><b><i>M</i></b><b>_w/p</b><b><i>I</i></b><b>^c</b>, experimental <i>M</i>_w/p<i>I</i>; <b>SC^d</b>, sequence coverage; <b>Score^e</b>, mascot search score against the NCBInr database; <b>Ratio^f</b>, different protein spot intensity ratios at different elevations relative to the control (4600 m).</p

Changes of metabolite content in <i>K. pygmaea</i> with elevation increasing.

<p><b>A</b>: Changes of photosynthetic pigment content in <i>K. pygmaea</i> at different elevations. <b>B</b>: Changes of abscisic acid and proline content in <i>K. pygmaea</i> along an elevational gradient. Error bars indicate SE. Means denoted by different letters were significantly different (<i>P</i><0.05).</p