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81.
Sj?gren-Larsson syndrome (SLS) is an inherited neurocutaneous disorder characterized by ichthyosis, mental retardation, spasticity, and deficient activity of fatty aldehyde dehydrogenase (FALDH). FALDH is an enzyme component of fatty alcohol:NAD oxidoreductase (FAO), which is necessary for fatty alcohol metabolism. To better understand the biochemical basis for the cutaneous symptoms in this disease, we investigated lipid metabolism in cultured keratinocytes from SLS patients. Enzyme activities of FALDH and FAO in SLS cells were <10% of normal. SLS keratinocytes accumulated 45-fold more fatty alcohol (hexadecanol, octadecanol, and octadecenol) than normal, whereas wax esters and 1-O-alkyl-2,3-diacylglycerols were increased by 5.6-fold and 7.5-fold, respectively. SLS keratinocytes showed a reduced incorporation of radioactive octadecanol into fatty acid (24% of normal) and triglyceride (13% of normal), but incorporation into wax esters and 1-O-alkyl-2,3-diacylglycerol was increased by 2.5-fold and 2.8-fold, respectively. Our results indicate that FALDH deficiency in SLS keratinocytes causes the accumulation and diversion of fatty alcohol into alternative biosynthetic pathways. The striking lipid abnormalities in cultured SLS keratinocytes are distinct from those seen in fibroblasts and may be related to the stratum corneum dysfunction and ichthyosis in SLS. 相似文献
82.
The recently identified benzoate oxidation (box) pathway in Burkholderia xenovorans LB400 (LB400 hereinafter) assimilates benzoate through a unique mechanism where each intermediate is processed as a coenzyme A (CoA) thioester. A key step in this process is the conversion of 3,4-dehydroadipyl-CoA semialdehyde into its corresponding CoA acid by a novel aldehyde dehydrogenase (ALDH) (EC 1.2.1.x). The goal of this study is to characterize the biochemical and structural properties of the chromosomally encoded form of this new class of ALDHs from LB400 (ALDHC) in order to better understand its role in benzoate degradation. To this end, we carried out kinetic studies with six structurally diverse aldehydes and nicotinamide adenine dinucleotide (phosphate) (NAD + and NADP +). Our data definitively show that ALDHC is more active in the presence of NADP + and selective for linear medium-chain to long-chain aldehydes. To elucidate the structural basis for these biochemical observations, we solved the 1.6-Å crystal structure of ALDHC in complex with NADPH bound in the cofactor-binding pocket and an ordered fragment of a polyethylene glycol molecule bound in the substrate tunnel. These data show that cofactor selectivity is governed by a complex network of hydrogen bonds between the oxygen atoms of the 2′-phosphoryl moiety of NADP + and a threonine/lysine pair on ALDHC. The catalytic preference of ALDHC for linear longer-chain substrates is mediated by a deep narrow configuration of the substrate tunnel. Comparative analysis reveals that reorientation of an extended loop (Asn478-Pro490) in ALDHC induces the constricted structure of the substrate tunnel, with the side chain of Asn478 imposing steric restrictions on branched-chain and aromatic aldehydes. Furthermore, a key glycine (Gly104) positioned at the mouth of the tunnel allows for maximum tunnel depth required to bind medium-chain to long-chain aldehydes. This study provides the first integrated biochemical and structural characterization of a box-pathway-encoded ALDH from any organism and offers insight into the catalytic role of ALDHC in benzoate degradation. 相似文献
83.
The pathophysiology of spinal cord injury (SCI) is characterized by the initial, primary injury followed by secondary injury processes in which oxidative stress is a critical component. Secondary injury processes not only exacerbate pathology at the site of primary injury, but also result in spreading of injuries to the adjacent, otherwise healthy tissue. The lipid peroxidation byproduct acrolein has been implicated as one potential mediator of secondary injury. To further and rigorously elucidate the role of acrolein in secondary injury, a unique ex vivo model is utilized to isolate the detrimental effects of mechanical injury from toxins such as acrolein that are produced endogenously following SCI. We demonstrate that (i) acrolein-Lys adducts are capable of diffusing from compressed tissue to adjacent, otherwise uninjured tissue; (ii) secondary injury by itself produces significant membrane damage and increased superoxide production; and (iii) these injuries are significantly attenuated by the acrolein scavenger hydralazine. Furthermore, hydralazine treatment results in significantly less membrane damage 2 h following compression injury, but not immediately after. These findings support our hypothesis that, following SCI, acrolein is increased to pathologic concentrations, contributes significantly to secondary injury, and thus represents a novel target for scavenging to promote improved recovery. 相似文献
84.
Nian-PengHE Xing-GuoHAN Qing-MinPAN 《植物学报(英文版)》2005,47(1):13-19
The biogenic volatile organic compounds (VOC) emitted by the vegetation of a terrestrial ecosystem play a key role in both regional air quality and tropospheric chemistry. To describe the general emission properties of VOC of different plant functional groups (PFG) in a typical temperate grassland in Inner Mongolia, China, we randomly selected 175 plant species and measured the quantities of isoprene and monoterpene in situ. Results showed that most plants had low VOC emission potential at the species level,especially for some dominant plants, such as Leymus chinensis Tzvel., Stipa grandis Smirn., and Agropyron cristatum Gaertn. At the PFG level, the lowest VOC emission potential was found for perennial rhizome grasses, a major PFG in a typical temperate grassland ecosystem. The effects of overgrazing and subsequent vegetation succession on the emission of VOC by different plant life form functional groups (PLFG)were also discussed. 相似文献
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86.
通过农杆菌介导法获得耐盐转甜菜碱醛脱氢酶基因白三叶草 总被引:21,自引:0,他引:21
通过农杆菌介导法将耐盐植物山菠菜甜菜碱醛脱氢酶(Betaine Aldehyde Dehydrogenase,BADH)基因成功地转化了白三叶草。转基因植株在经过48h 1%NaCl胁迫后相对电导率为20%左右,而非转基因植株高达40%,表明转基因植株细胞膜在盐胁迫下受到的伤害较非转基因的轻,并且转基因植株能够在含有0.5%NaCl的水培养中正常生长两周以上,而非转基因植株则呈现不正常生长。 相似文献
87.
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89.
Plants may activate similar defence systems to reduce cellular damages caused by different stress conditions. In the present experiments, the formation of lipid peroxidation products [thiobarbituric acid reactive species (TBARS)] was significant during both drought and ultraviolet (UV)‐B stresses, whereas the formation of reactive oxygen species (ROS) was a more delayed response to UV‐B than to drought. H2O2 was detected during both stresses, whereas ·OH radical production was a more characteristic response to drought. The present characterization of transgenic tobacco plants revealed a common role for aldose/aldehyde reductase (ALR) in the detoxification of lipid peroxidation products under water depletion and UV‐B irradiation. As the result of the increased synthesis of ALR enzyme, the transformed plants were more tolerant to both stress conditions, exhibiting reduced loss of photosynthetic function and decreased accumulation of TBARS and H2O2 as compared to control (SR1) plants. When plants had been exposed to mild, non‐lethal drought and were then watered again to recover, they were more tolerant to a subsequent stress by UV‐B. This was characteristic to both transgenic and wild‐type plants. However, this drought‐induced cross‐tolerance to UV‐B stress of SR1 tobacco did not reach the enhancement achieved by the overexpression of ALR. 相似文献
90.
Ana Rodríguez Takehiko Shimada Magdalena Cervera Ana Redondo Berta Alquézar María Jesús Rodrigo Lorenzo Zacarías Lluís Palou María M López Leandro Pe?a 《Plant signaling & behavior》2015,10(6)
Volatile organic compounds (VOCs) are secondary metabolites acting as a language for the communication of plants with the environment. In orange fruits, the monoterpene D-limonene accumulates at very high levels in oil glands from the peel. Drastic down-regulation of D-limonene synthase gene expression in the peel of transgenic oranges harboring a D-limonene synthase transgene in antisense (AS) configuration altered the monoterpene profile in oil glands, mainly resulting in reduced accumulation of D-limonene. This led to fruit resistance against Penicillium digitatum (Pd), Xanthomonas citri subsp. citri (Xcc) and other specialized pathogens. Here, we analyze resistance to pathogens in independent AS and empty vector (EV) lines, which have low, medium or high D-limonene concentrations and show that the level of resistance is inversely related to the accumulation of D-limonene in orange peels, thus explaining the need of high D-limonene accumulation in mature oranges in nature for the efficient attraction of specialized microorganism frugivores. 相似文献