scholarly journals Further Studies on the 3-Ketosteroid 9α-Hydroxylase of Rhodococcus ruber Chol-4, a Rieske Oxygenase of the Steroid Degradation Pathway

2021 ◽  
Vol 9 (6) ◽  
pp. 1171
Author(s):  
Sara Baldanta ◽  
Juana María Navarro Llorens ◽  
Govinda Guevara
Keyword(s):  
Cholesterol Metabolism ◽  
Genetic Regulation ◽  
Degradation Pathway ◽  
Rhodococcus Ruber ◽  
Promoter Regions ◽  
Steroid Nucleus ◽  
Steroid Substrate ◽  
Fine Regulation ◽  
Rieske Oxygenase ◽  
Steroid Catabolism

The biochemistry and genetics of the bacterial steroid catabolism have been extensively studied during the last years and their findings have been essential to the development of biotechnological applications. For instance, metabolic engineering of the steroid-eater strains has allowed to obtain intermediaries of industrial value. However, there are still some drawbacks that must be overcome, such as the redundancy of the steroid catabolism genes in the genome and a better knowledge of its genetic regulation. KshABs and KstDs are key enzymes involved in the aerobic breakage of the steroid nucleus. Rhodococcus ruber Chol-4 contains three kshAs genes, a single kshB gene and three kstDs genes within its genome. In the present work, the growth of R. ruber ΔkshA strains was evaluated on different steroids substrates; the promoter regions of these genes were analyzed; and their expression was followed by qRT-PCR in both wild type and ksh mutants. Additionally, the transcription level of the kstDs genes was studied in the ksh mutants. The results show that KshA2B and KshA1B are involved in AD metabolism, while KshA3B and KshA1B contribute to the cholesterol metabolism in R. ruber. In the kshA single mutants, expression of the remaining kshA and kstD genes is re-organized to survive on the steroid substrate. These data give insight into the fine regulation of steroid genes when several isoforms are present.

Corticosteroid Catabolism by Klebsiella pneumoniae as a Possible Mechanism for Increased Pneumonia Risk

2019 ◽  
Vol 20 (4) ◽  
pp. 309-316 ◽  
Author(s):  
Pritam Chattopadhyay ◽  
Goutam Banerjee
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Kegg Pathway ◽  
Degradation Pathway ◽  
Amino Acid Sequences ◽  
Biological Mechanism ◽  
Clinical Strains ◽  
Catabolism Pathway ◽  
Steroid Catabolism ◽  
Nutrition Source

Background: Several strains of Klebsiella pneumoniae are responsible for causing pneumonia in lung and thereby causing death in immune-suppressed patients. In recent year, few investigations have reported the enhancement of K. pneumoniae population in patients using corticosteroid containing inhaler. Objectives: The biological mechanism(s) behind this increased incidence has not been elucidated. Therefore, the objective of this investigating was to explore the relation between Klebsiella pneumoniae and increment in carbapenamase producing Enterobacteriaceae score (ICS). Methods: The available genomes of K. pneumoniae and the amino acid sequences of steroid catabolism pathway enzymes were taken from NCBI database and KEGG pathway tagged with UniPort database, respectively. We have used different BLAST algorithms (tBLASTn, BLASTp, psiBLAST, and delBLAST) to identify enzymes (by their amino acid sequence) involved in steroid catabolism. Results: A total of 13 enzymes (taken from different bacterial candidates) responsible for corticosteroid degradation have been identified in the genome of K. pneumoniae. Finally, 8 enzymes (K. pneumoniae specific) were detected in four clinical strains of K. pneumoniae. This investigation intimates that this ability to catabolize corticosteroids could potentially be one mechanism behind the increased pneumonia incidence. Conclusion: The presence of corticosteroid catabolism enzymes in K. pneumoniae enhances the ability to utilize corticosteroid for their own nutrition source. This is the first report to demonstrate the corticosteroid degradation pathway in clinical strains of K. pneumoniae.

scholarly journals Steroid Metabolism In Thermophilic Actinobacteria Saccharopolyspora Hirsuta Subsp. Hirsuta VKM Ac-666T

2021 ◽  
Author(s):  
Tatyana Gennadyevna Lobastova ◽  
Victoria V. Fokina ◽  
Sergey V. Tarlachkov ◽  
Andrey A. Shutov ◽  
Eugeny Yu. Bragin ◽  
...  
Keyword(s):  
Structural Modification ◽  
Thermophilic Bacteria ◽  
Cholesterol Oxidase ◽  
Bioinformatic Analysis ◽  
Degradation Pathway ◽  
Side Chain ◽  
P450 Monooxygenase ◽  
Key Genes ◽  
Saccharopolyspora Hirsuta ◽  
Steroid Catabolism

Abstract Application of thermophile microorganisms opens new prospects in steroid biotechnology, however little is known on steroid catabolism by the thermophile strains.The thermophilic Saccharopolyspora hirsuta subsp. hirsuta strain VKM Ac-666T is capable of structural modification of different steroids, and fully degrades cholesterol. The intermediates of the cholesterol degradation pathway were identified as cholest-4-en-3-one, cholesta-1,4-dien-3-one, 26-hydroxycholest-4-en-3-one, 3-oxo-cholest-4-en-26-oic acid, 3-oxo-cholesta-1,4-dien-26-oic acid, 26-hydroxycholesterol, 3β-hydroxy-cholest-5-en-26-oic acid by MS, and H1- and C13-NMR analyses. The data evidence sterol degradation by the strain occurs simultaneously through the aliphatic side chain hydroxylation at C26 and the A-ring modification that are putatively catalyzed by cytochrome P450 monooxygenase CYP125 and cholesterol oxidase, respectively.The genes orthologous to those related to the sterol side chain degradation, steroid core rings A/B and C/D disruption and the steroid uptake were revealed. Most of the genes related to steroid degradation are grouped in three clusters. The sets of the genes putatively involved in steroid catabolism and peculiarities of their organization in S. hirsuta are discussed.Despite steroids abundancy in the environments, the ability to degrade them is not widespread among thermophilic bacteria as follows from the bioinformatic analysis of 52 publicly available genomes. Only seven candidate strains were revealed to possess the key genes related to the only known 9(10)-seco pathway of steroid degradation.The results contribute to the knowledge on diversity of microbial steroid degraders, the features of sterol catabolism by thermophilic actinobacteria and could be useful for application in the pharmaceutical and environmental biotechnology.

scholarly journals MicroRNA Regulation of Cholesterol Metabolism

Cholesterol ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Noemi Rotllan ◽  
Carlos Fernández-Hernando
Keyword(s):  
Type Ii Diabetes ◽  
Cholesterol Metabolism ◽  
Critical Role ◽  
Cholesterol Homeostasis ◽  
Microrna Regulation ◽  
Fine Regulation ◽  
Lipid Metabolism Genes ◽  
Pathologic Processes ◽  
Metabolic Adjustment

Disruption of cellular cholesterol balance results in pathologic processes including atherosclerosis, metabolic syndrome, type II diabetes and Alzheimer’s disease. Maintenance of cholesterol homeostasis requires constant metabolic adjustment, achieved partly through the fine regulation of the classical transcription factors (e.g., by SREBP and LXR), but also through members of a class of noncoding RNAs termed miRNAs. Some miRNAs have now been identified to be potent post-transcriptional regulators of lipid metabolism genes, including miR-122, miR-33, miR-758, and miR-106b. Different strategies have been developed to modulate miRNA effects for therapeutic purposes. The promise demonstrated by the use of anti-miRs in human preclinical studies, in the case of miR-122, raises the possibility that miR-33, miR-758, and miR-106b may become viable therapeutic targets in future. This review summarizes the evidence for a critical role of some miRNAs in regulating cholesterol metabolism and suggests novel ways to manage dyslipidemias and cardiovascular diseases.

scholarly journals Folding and Persistence Time of Intramolecular G-Quadruplexes Transiently Embedded in a DNA duplex

2021 ◽  
Author(s):  
Phong Lan Thao Tran ◽  
Martin Rieu ◽  
Samar Hodeib ◽  
Alexandra Joubert ◽  
Jimmy Ouellet ◽  
...  
Keyword(s):  
Single Molecule ◽  
Critical Role ◽  
Genetic Regulation ◽  
Regulatory Elements ◽  
Promoter Regions ◽  
Folding Rate ◽  
Persistence Time ◽  
G4 Dna

ABSTRACTG-quadruplex (G4) DNA structures have emerged as important regulatory elements during DNA replication, transcription or repair. While many in-vitro studies have focused on the kinetics of G4 formation within DNA single-strands, G4 are found in-vivo in double-stranded DNA regions, where their formation is challenged by pairing between the two complementary strands. Since the energy of hybridization of Watson-Crick structures dominates the energy of G4 folding, this competition should play a critical role on the persistence of G4 in vivo. To address this issue, we designed a single molecule assay allowing measuring G4 folding and persistence while the structure is periodically challenged by the complementary strand. We quantified both the folding rate and the persistence time of biologically relevant G4 structures and showed that the dynamics of G4 formation depends strongly on the genomic location. G4 are found much more stable in promoter regions and replication origins than in telomeric regions. In addition, we characterized how G4 dynamics was affected by G4 ligands and showed that both folding rate and persistence increased. Our assay opens new perspectives for the measurement of G4 dynamics, which is critical to understand their role in genetic regulation.

scholarly journals Delineation of Steroid-Degrading Microorganisms through Comparative Genomic Analysis

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Lee H. Bergstrand ◽  
Erick Cardenas ◽  
Johannes Holert ◽  
Jonathan D. Van Hamme ◽  
William W. Mohn
Keyword(s):  
Pathogenic Bacteria ◽  
Gene Clusters ◽  
Degradation Pathway ◽  
Steroid Metabolism ◽  
Individual Species ◽  
Ecological Niches ◽  
Comparative Genomic ◽  
Bacterial Strains ◽  
Pathway Gene ◽  
Steroid Catabolism

ABSTRACT Steroids are ubiquitous in natural environments and are a significant growth substrate for microorganisms. Microbial steroid metabolism is also important for some pathogens and for biotechnical applications. This study delineated the distribution of aerobic steroid catabolism pathways among over 8,000 microorganisms whose genomes are available in the NCBI RefSeq database. Combined analysis of bacterial, archaeal, and fungal genomes with both hidden Markov models and reciprocal BLAST identified 265 putative steroid degraders within only Actinobacteria and Proteobacteria , which mainly originated from soil, eukaryotic host, and aquatic environments. These bacteria include members of 17 genera not previously known to contain steroid degraders. A pathway for cholesterol degradation was conserved in many actinobacterial genera, particularly in members of the Corynebacterineae , and a pathway for cholate degradation was conserved in members of the genus Rhodococcus . A pathway for testosterone and, sometimes, cholate degradation had a patchy distribution among Proteobacteria . The steroid degradation genes tended to occur within large gene clusters. Growth experiments confirmed bioinformatic predictions of steroid metabolism capacity in nine bacterial strains. The results indicate there was a single ancestral 9,10-seco-steroid degradation pathway. Gene duplication, likely in a progenitor of Rhodococcus , later gave rise to a cholate degradation pathway. Proteobacteria and additional Actinobacteria subsequently obtained a cholate degradation pathway via horizontal gene transfer, in some cases facilitated by plasmids. Catabolism of steroids appears to be an important component of the ecological niches of broad groups of Actinobacteria and individual species of Proteobacteria . IMPORTANCE Steroids are ubiquitous growth substrates for environmental and pathogenic bacteria, and bacterial steroid metabolism has important pharmaceutical and health applications. To date, the genetics and biochemistry of microbial steroid degradation have mainly been studied in a few model bacteria, and the diversity of this metabolism remains largely unexplored. Here, we provide a bioinformatically derived perspective of the taxonomic distribution of aerobic microbial steroid catabolism pathways. We identified several novel steroid-degrading bacterial groups, including ones from marine environments. In several cases, we confirmed bioinformatic predictions of metabolism in cultures. We found that cholesterol and cholate catabolism pathways are highly conserved among certain actinobacterial taxa. We found evidence for horizontal transfer of a pathway to several proteobacterial genera, conferring testosterone and, sometimes, cholate catabolism. The results of this study greatly expand our ecological and evolutionary understanding of microbial steroid metabolism and provide a basis for better exploiting this metabolism for biotechnology.

scholarly journals Long-term consumption of plant stanol and sterol esters, vascular function and genetic regulation

2008 ◽  
Vol 101 (11) ◽  
pp. 1688-1695 ◽  
Author(s):  
Helena Gylling ◽  
Maarit Hallikainen ◽  
Olli T. Raitakari ◽  
Markku Laakso ◽  
Erkki Vartiainen ◽  
...  
Keyword(s):  
Serum Cholesterol ◽  
Vascular Function ◽  
Cholesterol Metabolism ◽  
Genetic Regulation ◽  
Intima Media Thickness ◽  
Cholesterol Absorption ◽  
Sterol Esters ◽  
Brachial Artery Diameter ◽  
Plant Stanol

Polymorphisms of the ABCG5 and ABCG8 genes interfere with cholesterol absorption and synthesis. We determined whether common polymorphisms of these genes regulate the responses of serum cholesterol and vascular function during long-term inhibition of cholesterol absorption. Mildly to moderately hypercholesterolaemic subjects (n 282) completed a 1-year study consuming plant stanol or sterol ester (2 g stanol or sterol) or control spread. Serum cholesterol and non-cholesterol sterols, markers of cholesterol absorption and synthesis, and variables of vascular function and structure were analysed in relation to common polymorphisms of ABCG5 and ABCG8. At baseline, subjects with the 54K allele of ABCG8 had higher brachial endothelial-dependent flow-mediated dilatation than those without it (5·79 (se 0·31) v. 4·46 (se 0·44) %; P = 0·049), and subjects with the 632V allele of ABCG8 had larger brachial artery diameter than those without it. Polymorphisms of ABCG5 and ABCG8 were neither associated with serum cholesterol reduction nor changes in cholesterol metabolism or in vascular function. However, in subjects with the 400K allele of ABCG8, intima media thickness (IMT) was increased in all groups more than in those without it (P < 0·05). In conclusion, serum cholesterol lowering with absorption inhibition was not associated with polymorphic sites of ABCG5 and ABCG8. However, regulation of baseline cholesterol metabolism and vascular function and structure, and IMT progression during 1 year seemed to share some of the common polymorphic sites of these genes, suggesting a gene-regulated interaction between cholesterol metabolism and vascular function and structure.

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