Insights into the functional mechanism of the non-specific lipid transfer protein nsLTP in Kalanchoe fedtschenkoi (Lavender scallops).

Plant non-specific lipid transfer protein (nsLTP) is able to bind and transport lipids and essential oils, as well as engage in various physiological processes, including defense against phytopathogens. Kalanchoe fedtschenkoi (Lavender Scallops) is an attractive and versatile succulent. To investigate the functional mechanism of Kalanchoe fedtschenkoi nsLTP (Ka-nsLTP), we expressed, purified and successfully obtained monomeric Ka-nsLTP. Mutational experiments revealed that the C6A variant retained the same activity as the wild-type (WT) Ka-nsLTP. Ka-nsLTP showed weak antiphytopathogenic bacterial activity, but inhibited fungal growth. Ka-nsLTP possessed a hydrophobic cavity effectively binding lauric acid. Our results offer novel molecular insights into the functional mechanism of nsLTP, which broadens our knowledge of the biological function of nsLTP in crops and provides a useful locus for genetic improvement of plants.

Liu D ，Dou W ，Song H ，Deng H ，Tian Z ，Chen R ，Liu Z ，Jiao Z ，Akhberdi O ... -  《-》

Light-responsive expression atlas reveals the effects of light quality and intensity in Kalanchoë fedtschenkoi, a plant with crassulacean acid metabolism.

Crassulacean acid metabolism (CAM), a specialized mode of photosynthesis, enables plant adaptation to water-limited environments and improves photosynthetic efficiency via an inorganic carbon-concentrating mechanism. Kalanchoë fedtschenkoi is an obligate CAM model featuring a relatively small genome and easy stable transformation. However, the molecular responses to light quality and intensity in CAM plants remain understudied. Here we present a genome-wide expression atlas of K. fedtschenkoi plants grown under 12 h/12 h photoperiod with different light quality (blue, red, far-red, white light) and intensity (0, 150, 440, and 1,000 μmol m-2 s-1) based on RNA sequencing performed for mature leaf samples collected at dawn (2 h before the light period) and dusk (2 h before the dark period). An eFP web browser was created for easy access of the gene expression data. Based on the expression atlas, we constructed a light-responsive co-expression network to reveal the potential regulatory relationships in K. fedtschenkoi. Measurements of leaf titratable acidity, soluble sugar, and starch turnover provided metabolic indicators of the magnitude of CAM under the different light treatments and were used to provide biological context for the expression dataset. Furthermore, CAM-related subnetworks were highlighted to showcase genes relevant to CAM pathway, circadian clock, and stomatal movement. In comparison with white light, monochrome blue/red/far-red light treatments repressed the expression of several CAM-related genes at dusk, along with a major reduction in acid accumulation. Increasing light intensity from an intermediate level (440 μmol m-2 s-1) of white light to a high light treatment (1,000 μmol m-2 s-1) increased expression of several genes involved in dark CO2 fixation and malate transport at dawn, along with an increase in organic acid accumulation. This study provides a useful genomics resource for investigating the molecular mechanism underlying the light regulation of physiology and metabolism in CAM plants. Our results support the hypothesis that both light intensity and light quality can modulate the CAM pathway through regulation of CAM-related genes in K. fedtschenkoi.

Zhang J ，Hu R ，Sreedasyam A ，Garcia TM ，Lipzen A ，Wang M ，Yerramsetty P ，Liu D ，Ng V ，Schmutz J ，Cushman JC ，Borland AM ，Pasha A ，Provart NJ ，Chen JG ，Muchero W ，Tuskan GA ，Yang X ... -  《GigaScience》

Structural insights into the lipid transfer mechanism of a non-specific lipid transfer protein.

The non-specific lipid transfer proteins (nsLTPs) are multifunctional seed proteins engaged in several different physiological processes. The nsLTPs are stabilized by four disulfide bonds and exhibit a characteristic hydrophobic cavity, which is the primary lipid binding site. While these proteins are known to transfer lipids between membranes, the mechanism of lipid transfer has remained elusive. Four crystal structures of nsLTP from Solanum melongena, one in the apo-state and three myristic acid bound states were determined. Among the three lipid bound states, two lipid molecules were bound on the nsLTP surface at different positions and one was inside the cavity. The lipid-dependent conformational changes leading to opening of the cavity were revealed based on structural and spectroscopic data. The surface-bound lipid represented a transient intermediate state and the lipid ultimately moved inside the cavity through the cavity gate as revealed by molecular dynamics simulations. Two critical residues in the loop regions played possible 'gating' role in the opening and closing of the cavity. Antifungal activity and membrane permeabilization effect of nsLTP against Fusarium oxysporum suggested that it could possibly involve in bleaching out the lipids. Collectively, these studies support a model of lipid transfer mechanism by nsLTP via intermediate states.

Madni ZK ，Tripathi SK ，Salunke DM 《-》

Evolution of non-specific lipid transfer protein (nsLTP) genes in the Poaceae family: their duplication and diversity.

Jang CS ，Yim WC ，Moon JC ，Hung JH ，Lee TG ，Lim SD ，Cho SH ，Lee KK ，Kim W ，Seo YW ，Lee BM ... -  《-》

Transfer of cholesterol and oxysterol derivatives by the nonspecific lipid transfer protein (sterol carrier protein 2): a study on its mode of action.

van Amerongen A ，Demel RA ，Westerman J ，Wirtz KW ... -  《-》