Os09g0567800

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Annotated Information

Function

This gene encodes an lipolytic enzyme(lipase) involved in the degradation of fat,which will form fatty acids, glycerol and monoglyceride or diacylglycerol.lipolytic enzyme perform essential roles in the digestion, transport and processing of dietary lipids (e.g. triglycerides, fats, oils) in most, if not all, living organisms.Most lipases act at a specific position on the glycerol backbone of lipid substrate (A1, A2 or A3)(small intestine). Lipases are involved in diverse biological processes ranging from routine metabolism of dietary triglycerides to cell signaling and inflammation.Thus, some lipase activities are confined to specific compartments within cells while others work in extracellular spaces.Other lipase enzymes, such as pancreatic lipases, are secreted into extracellular spaces where they serve to process dietary lipids into more simple forms that can be more easily absorbed and transported throughout the body.As biological membranes are integral to living cells and are largely composed of phospholipids, lipases also play important roles in cell biology.

Expression

Lipases are important biocatalysts showing many interesting properties with industrial applications. Previously, different isoforms of lipases, Lipase-I and Lipase-II from rice (Oryza sativa) have been purified and characterized. Lipase-II identified as the major lipase in rice bran is designated as rice bran lipase (RBL). An exploration of expression in four different E. coli expression systems analyzed: BL21(DE3)pLysS, RIL(DE3)pLysS, Rosetta(DE3)pLysS and Origami(DE3)pLysS indicated that E. coli was not a suitable host. Expression with supplement of rare codons in Rosetta (DE3)pLysS and RIL(DE3)pLysS resulted in highest expression as insoluble inclusion bodies. The hurdles of expression in E. coli were overcome by expression as a secretory protein in P. pastoris X-33. The expression of lipase in shake flasks was optimized to achieve the maximum recombinant lipase activity of 152.6 U/mL. The purified recombinant lipase had a specific activity of 998 U/mg toward triacetin. The pH and temperature optimum of native and recombinant enzymes were pH 7.4 and 25 ± 2 °C, respectively. Both the lipases showed higher activity toward short chain triacylglycerol and unsaturated fatty acid enriched oils. Computational modeling and molecular docking studies reveal that the catalytic efficiency of the lipase correlates with the distance of the nucleophilic Ser(175)-OH and the scissile ester bond. The shorter the distance, the greater is the turnover of the substrate.

Evolution

one study characterized a rice mutant, the most obvious phenotypes of which are high tillering, reduced height, and infertile spikelets (named this1). Similarly to the high tiller number and dwarf mutants in rice, the increased tiller number of this1 plants is ascribed to the release of tiller bud outgrowth rather than to increased tiller bud formation. In the this1 mutant, however, the accelerated rate of branching was delayed until the stem elongation stage, while other mutants lost the ability to control branching at all developmental stages. The seed-setting rate of this1 was less than half that of the wild type, owing to defects in pollen maturation, anther dehiscence, and flower opening. Histological analyses showed that the mutation in this1 resulted in anisotropic cell expansion and cell division. Using a map-based cloning approach, This1 was found to encode a class III lipase. Homology searches revealed that THIS1 is conserved in both monocots and eudicots, suggesting that it plays fundamental role in regulating branch and spikelet fertility, as well as other aspects of developmental control. The relative change in expression of marker genes highlighted the possibility that This1 is involved in phytohormone signalling pathways, such as those for strigolactone and auxin. Thus, This1 provides joint control between shoot branching and reproductive development.

Labs working on this gene

• Department of Biochemistry and Molecular Biology ,Oklahoma University Health Sciences Center, Oklahoma City, USA.

• Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, DC 20007, USA

• Department of Biological Sciences, Hunter College of City University of New York, 695 Park Ave, New York, NY 10021, USA

• Laboratory of Signal Transduction, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA

• The Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah 84112

• Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.