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Microbial enzyme systems for lignin degradation and their transcriptional regulation
Takanori FURUKAWA,Fatai Olumide BELLO,Louise HORSFALL
Front. Biol.. 2014, 9 (6 ): 448-471.
https://doi.org/10.1007/s11515-014-1336-9
Lignocellulosic biomass is the most abundant renewable resource in nature and has received considerable attention as one of the most promising alternatives to oil resources for the provision of energy and certain raw materials. The phenolic polymer lignin is the second most abundant constituent of this biomass resource and has been shown to have the potential to be converted into industrially important aromatic chemicals after degradation. However, due to its chemical and structural nature, it exhibits high resistance toward mechanical, chemical, and biological degradation, and this causes a major obstacle for achieving efficient conversion of lignocellulosic biomass. In nature, lignin-degrading microorganisms have evolved unique extracellular enzyme systems to decompose lignin using radical mediated oxidative reactions. These microorganisms produce a set of different combinations of enzymes with multiple isozymes and isoforms by responding to various environmental stimuli such as nutrient availability, oxygen concentration and temperature, which are thought to enable effective decomposition of the lignin in lignocellulosic biomass. In this review, we present an overview of the microbial ligninolytic enzyme systems including general molecular aspects, structural features, and systematic differences in each microorganism. We also describe the gene expression pattern and the transcriptional regulation mechanisms of each ligninolytic enzyme with current data.
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Comparative analysis of chromosome segregation in human, yeasts and trypanosome
Xianxian HAN,Ziyin LI
Front. Biol.. 2014, 9 (6 ): 472-480.
https://doi.org/10.1007/s11515-014-1334-y
Chromosome segregation is a tightly regulated process through which duplicated genetic materials are equally partitioned into daughter cells. During the past decades, tremendous efforts have been made to understand the molecular mechanism of chromosome segregation using animals and yeasts as model systems. Recently, new insights into chromosome segregation have gradually emerged using trypanosome, an early branching parasitic protozoan, as a model organism. To uncover the unique aspects of chromosome segregation in trypanosome, which potentially could serve as new drug targets for anti-trypanosome chemotherapy, it is necessary to perform a comparative analysis of the chromosome segregation machinery between trypanosome and its human host. Here, we briefly review the current knowledge about chromosome segregation in human and Trypanosoma brucei , with a focus on the regulation of cohesin and securin degradation triggered by the activation of the anaphase promoting complex/cyclosome (APC/C). We also include yeasts in our comparative analysis since some of the original discoveries were made using budding and fission yeasts as the model organisms and, therefore, these could provide hints about the evolution of the machinery. We highlight both common and unique features in these model systems and also provide perspectives for future research in trypanosome.
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Role of BDNF in the taste system
Lingbin MENG,Xiaolei CHEN,Rongqiang YANG,Rui JI
Front. Biol.. 2014, 9 (6 ): 481-488.
https://doi.org/10.1007/s11515-014-1335-x
Neurotrophins are a family of proteins that regulate neural survival, development, function and plasticity in the central and the peripheral nervous system. There are four neurotrophins: NGF, BDNF, NT-3 and NT-4. Among them, BDNF is mostly studied in the taste system due to its high expression. Recent studies have shown BDNF play an important role in the developmental and mature taste system, by regulating survival of taste cells and geniculate ganglion neurons, and maintaining and guiding taste nerve innervations. These studies imply BDNF has great potentialities for therapeutic usage to enhance sensory regeneration following nerve injury, with aging, and in some neurodegenerative diseases.
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Mitochondrial dysfunction in Parkinson’s disease: a possible target for neuroprotection
Jacqueline A. GLEAVE,Peter D. PERRI,Joanne E. NASH
Front. Biol.. 2014, 9 (6 ): 489-503.
https://doi.org/10.1007/s11515-014-1337-8
Mitochondria are dynamic organelles which are required for maintaining cellular homeostasis. Thus, it is not surprising that irregularities in mitochondrial function result in cellular damage and are linked with neurodegenerative diseases, such as Parkinson’s disease. Evidence that mitochondrial dysfunction is key to the pathogenesis of Parkinson’s disease is founded in studies in post-mortem tissue from patients with Parkinson’s disease, and also from genetic studies stemming from patients with familial Parkinson’s disease. Whether triggered by environmental or genetic factors, mitochondrial dysfunction occurs early in the pathogenic process, and is central to Parkinson’s disease pathology. As such, targeting the mitochondria to slow or halt disease progression is an attractive strategy for disease-modifying agents in Parkinson’s disease. Indeed, several therapies which target the mitochondria have been investigated as neuroprotective treatments for Parkinson’s disease. This review will discuss the evidence supporting mitochondrial dysfunction in Parkinson’s disease pathology as well as treatment strategies that target the mitochondria.
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Influence of the SNPs on the structural stability of CBS protein: Insight from molecular dynamics simulations
C. GEORGE PRIYA DOSS,B. RAJITH,R. MAGESH,A. ASHISH KUMAR
Front. Biol.. 2014, 9 (6 ): 504-518.
https://doi.org/10.1007/s11515-014-1320-4
Cystathionine β-synthase is an essential enzyme of the trans-sulfuration pathway that condenses serine with homocysteine to form cystathionine. Missense mutations in CBS are the major cause of inherited homocystinuria, and the detailed effect of disease associated amino acid substitutions on the structure and stability of human CBS is yet unknown. Here, we apply a unique approach in combining in silico tools and molecular dynamics simulation to provide structural and functional insight into the effect of SNP on the stability and activity of mutant CBS. In addition, principal component analysis and free energy landscape were used to predict the collective motions, thermodynamic stabilities and essential subspace relevant to CBS function. The obtained results indicate that C109R, E176K and D376N mutations have the diverse effect on dynamic behavior of CBS protein. We found that highly conserved D376N mutation, which is present in the active pocket, affects the protein folding mechanism. Our strategy may provide a way in near future to understand and study effects of functional nsSNPs and their role in causing homocystinuria.
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