scholarly journals Metabolism of Four α-Glycosidic Linkage-Containing Oligosaccharides by Bifidobacterium breve UCC2003

2013 ◽  
Vol 79 (20) ◽  
pp. 6280-6292 ◽  
Author(s):  
Kerry Joan O'Connell ◽  
Mary O'Connell Motherway ◽  
John O'Callaghan ◽  
Gerald F. Fitzgerald ◽  
R. Paul Ross ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Molecular Mechanisms ◽  
Functional Genomic ◽  
Adjacent Gene ◽  
Glycosidic Linkage ◽  
Carbohydrate Utilization ◽  
Content Type ◽  
Bifidobacterium Breve

ABSTRACTMembers of the genusBifidobacteriumare common inhabitants of the gastrointestinal tracts of humans and other mammals, where they ferment many diet-derived carbohydrates that cannot be digested by their hosts. To extend our understanding of bifidobacterial carbohydrate utilization, we investigated the molecular mechanisms by which 11 strains ofBifidobacterium brevemetabolize four distinct α-glucose- and/or α-galactose-containing oligosaccharides, namely, raffinose, stachyose, melibiose, and melezitose. Here we demonstrate that allB. brevestrains examined possess the ability to utilize raffinose, stachyose, and melibiose. However, the ability to metabolize melezitose was not common to allB. brevestrains tested. Transcriptomic and functional genomic approaches identified a gene cluster dedicated to the metabolism of α-galactose-containing carbohydrates, while an adjacent gene cluster, dedicated to the metabolism of α-glucose-containing melezitose, was identified in strains that are able to use this carbohydrate.

scholarly journals Comparative Genomic and Functional Analysis of Lactobacillus casei and Lactobacillus rhamnosus Strains Marketed as Probiotics

2013 ◽  
Vol 79 (6) ◽  
pp. 1923-1933 ◽  
Author(s):  
François P. Douillard ◽  
Angela Ribbera ◽  
Hanna M. Järvinen ◽  
Ravi Kant ◽  
Taija E. Pietilä ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Transcription Initiation ◽  
Lactobacillus Rhamnosus ◽  
Comparative Genomic ◽  
Phenotypic Analysis ◽  
Carbohydrate Utilization ◽  
Content Type ◽  
Host Signaling ◽  
Toll Like Receptor 2 ◽  
Genome Content

ABSTRACTFourLactobacillusstrains were isolated from marketed probiotic products, includingL. rhamnosusstrains from Vifit (Friesland Campina) and Idoform (Ferrosan) andL. caseistrains from Actimel (Danone) and Yakult (Yakult Honsa Co.). Their genomes and phenotypes were characterized and compared in detail withL. caseistrain BL23 andL. rhamnosusstrain GG. Phenotypic analysis of the new isolates indicated differences in carbohydrate utilization betweenL. caseiandL. rhamnosusstrains, which could be linked to their genotypes. The two isolatedL. rhamnosusstrains had genomes that were virtually identical to that ofL. rhamnosusGG, testifying to their genomic stability and integrity in food products. TheL. caseistrains showed much greater genomic heterogeneity. Remarkably, all strains contained an intactspaCBApilus gene cluster. However, only theL. rhamnosusstrains produced mucus-binding SpaCBA pili under the conditions tested. Transcription initiation mapping demonstrated that the insertion of aniso-IS30element upstream of the pilus gene cluster inL. rhamnosusstrains but absent inL. caseistrains had constituted a functional promoter driving pilus gene expression. AllL. rhamnosusstrains triggered an NF-κB response via Toll-like receptor 2 (TLR2) in a reporter cell line, whereas theL. caseistrains did not or did so to a much lesser extent. This study demonstrates that the twoL. rhamnosusstrains isolated from probiotic products are virtually identical toL. rhamnosusGG and further highlights the differences between these andL. caseistrains widely marketed as probiotics, in terms of genome content, mucus-binding and metabolic capacities, and host signaling capabilities.

scholarly journals Multiple Transporters and Glycoside Hydrolases Are Involved in Arabinoxylan-Derived Oligosaccharide Utilization in Bifidobacterium pseudocatenulatum

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Yuki Saito ◽  
Akira Shigehisa ◽  
Yohei Watanabe ◽  
Naoki Tsukuda ◽  
Kaoru Moriyama-Ohara ◽  
...  
Keyword(s):  
Abc Transporters ◽  
Binding Proteins ◽  
Molecular Mechanisms ◽  
Bifidobacterium Longum ◽  
Gene Clusters ◽  
Glycoside Hydrolases ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Utilization ◽  
Bifidobacterium Adolescentis ◽  
Content Type

ABSTRACT Arabinoxylan hydrolysates (AXH) are the hydrolyzed products of the major components of the dietary fiber arabinoxylan. AXH include diverse oligosaccharides varying in xylose polymerization and side residue modifications with arabinose at the O-2 and/or O-3 position of the xylose unit. Previous studies have reported that AXH exhibit prebiotic properties on gut bifidobacteria; moreover, several adult-associated bifidobacterial species (e.g., Bifidobacterium adolescentis and Bifidobacterium longum subsp. longum) are known to utilize AXH. In this study, we tried to elucidate the molecular mechanisms of AXH utilization by Bifidobacterium pseudocatenulatum, which is a common bifidobacterial species found in adult feces. We performed transcriptomic analysis of B. pseudocatenulatum YIT 4072T, which identified three upregulated gene clusters during AXH utilization. The gene clusters encoded three sets of ATP-binding cassette (ABC) transporters and five enzymes belonging to glycoside hydrolase family 43 (GH43). By characterizing the recombinant proteins, we found that three solute-binding proteins of ABC transporters showed either broad or narrow specificity, two arabinofuranosidases hydrolyzed either single- or double-decorated arabinoxylooligosaccharides, and three xylosidases exhibited functionally identical activity. These data collectively suggest that the transporters and glycoside hydrolases, encoded in the three gene clusters, work together to utilize AXH of different sizes and with different side residue modifications. Thus, our study sheds light on the overall picture of how these proteins collaborate for the utilization of AXH in B. pseudocatenulatum and may explain the predominance of this symbiont species in the adult human gut. IMPORTANCE Bifidobacteria commonly reside in the human intestine and possess abundant genes involved in carbohydrate utilization. Arabinoxylan hydrolysates (AXH) are hydrolyzed products of arabinoxylan, one of the most abundant dietary fibers, and they include xylooligosaccharides and those decorated with arabinofuranosyl residues. The molecular mechanism by which B. pseudocatenulatum, a common bifidobacterial species found in adult feces, utilizes structurally and compositionally variable AXH has yet to be extensively investigated. In this study, we identified three gene clusters (encoding five GH43 enzymes and three solute-binding proteins of ABC transporters) that were upregulated in B. pseudocatenulatum YIT 4072T during AXH utilization. By investigating their substrate specificities, we revealed how these proteins are involved in the uptake and degradation of AXH. These molecular insights may provide a better understanding of how resident bifidobacteria colonize the colon.

scholarly journals A SilencedvanAGene Cluster on a Transferable Plasmid Caused an Outbreak of Vancomycin-Variable Enterococci

2016 ◽  
Vol 60 (7) ◽  
pp. 4119-4127 ◽  
Author(s):  
Audun Sivertsen ◽  
Torunn Pedersen ◽  
Kjersti Wik Larssen ◽  
Kåre Bergh ◽  
Torunn Gresdal Rønning ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Molecular Mechanisms ◽  
Genetic Difference ◽  
Brain Heart Infusion ◽  
Broad Host Range ◽  
S1 Nuclease ◽  
Content Type ◽  
Transcription Profiles

ABSTRACTWe report an outbreak of vancomycin-variablevanA+enterococci (VVE) able to escape phenotypic detection by current guidelines and demonstrate the molecular mechanisms forin vivoswitching into vancomycin resistance and horizontal spread of thevanAcluster. Forty-eightvanA+Enterococcus faeciumisolates and oneEnterococcus faecalisisolate were analyzed for clonality with pulsed-field gel electrophoresis (PFGE), and theirvanAgene cluster compositions were assessed by PCR and whole-genome sequencing of six isolates. The susceptible VVE strains were cultivated in brain heart infusion broth containing vancomycin at 8 μg/ml forin vitrodevelopment of resistant VVE. The transcription profiles of susceptible VVE and their resistant revertants were assessed using quantitative reverse transcription-PCR. Plasmid content was analyzed with S1 nuclease PFGE and hybridizations. Conjugative transfer ofvanAwas assessed by filter mating. The only genetic difference between thevanAclusters of susceptible and resistant VVE was an ISL3-family element upstream ofvanHAX, which silencedvanHAXgene transcription in susceptible VVE. Furthermore, the VVE had an insertion of IS1542betweenorf2andvanRthat attenuated the expression ofvanHAX. Growth of susceptible VVE occurred after 24 to 72 h of exposure to vancomycin due to excision of the ISL3-family element. ThevanAgene cluster was located on a transferable broad-host-range plasmid also detected in outbreak isolates with different pulsotypes, including oneE. faecalisisolate. Horizontally transferable silencedvanAable to escape detection and revert into resistance during vancomycin therapy represents a new challenge in the clinic. Genotypic testing of invasive vancomycin-susceptible enterococci byvanA-PCR is advised.

scholarly journals Mechanistic Study of Utilization of Water-Insoluble Saccharomyces cerevisiae Glucans by Bifidobacterium breve Strain JCM1192

2017 ◽  
Vol 83 (7) ◽  
Author(s):  
Hoi Yee Keung ◽  
Tsz Kai Li ◽  
Lok To Sham ◽  
Man Kit Cheung ◽  
Peter Chi Keung Cheung ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Abc Transporter ◽  
Transport System ◽  
Binding Protein ◽  
Atp Binding ◽  
Carbohydrate Utilization ◽  
Content Type ◽  
Bifidobacterium Breve ◽  
Abc Transport ◽  
Atp Binding Protein

ABSTRACT Bifidobacteria exert beneficial effects on hosts and are extensively used as probiotics. However, due to the genetic inaccessibility of these bacteria, little is known about their mechanisms of carbohydrate utilization and regulation. Bifidobacterium breve strain JCM1192 can grow on water-insoluble yeast (Saccharomyces cerevisiae) cell wall glucans (YCWG), which were recently considered as potential prebiotics. According to the results of 1H nuclear magnetic resonance (NMR) spectrometry, the YCWG were composed of highly branched (1→3,1→6)-β-glucans and (1→4,1→6)-α-glucans. Although the YCWG were composed of 78.3% β-glucans and 21.7% α-glucans, only α-glucans were consumed by the B. breve strain. The ABC transporter (malEFG1) and pullulanase (aapA) genes were transcriptionally upregulated in the metabolism of insoluble yeast glucans, suggesting their potential involvement in the process. A nonsense mutation identified in the gene encoding an ABC transporter ATP-binding protein (MalK) led to growth failure of an ethyl methanesulfonate-generated mutant with yeast glucans. Coculture of the wild-type strain and the mutant showed that this protein was responsible for the import of yeast glucans or their breakdown products, rather than the export of α-glucan-catabolizing enzymes. Further characterization of the carbohydrate utilization of the mutant and three of its revertants indicated that this mutation was pleiotropic: the mutant could not grow with maltose, glycogen, dextrin, raffinose, cellobiose, melibiose, or turanose. We propose that insoluble yeast α-glucans are hydrolyzed by extracellular pullulanase into maltose and/or maltooligosaccharides, which are then transported into the cell by the ABC transport system composed of MalEFG1 and MalK. The mechanism elucidated here will facilitate the development of B. breve and water-insoluble yeast glucans as novel synbiotics. IMPORTANCE In general, Bifidobacterium strains are genetically intractable. Coupling classic forward genetics with next-generation sequencing, here we identified an ABC transporter ATP-binding protein (MalK) responsible for the import of insoluble yeast glucan breakdown products by B. breve JCM1192. We demonstrated the pleiotropic effects of the ABC transporter ATP-binding protein in maltose/maltooligosaccharide, raffinose, cellobiose, melibiose, and turanose transport. With the addition of transcriptional analysis, we propose that insoluble yeast glucans are broken down by extracellular pullulanase into maltose and/or maltooligosaccharides, which are then transported into the cell by the ABC transport system composed of MalEFG1 and MalK. The mechanism elucidated here will facilitate the development of B. breve and water-insoluble yeast glucans as novel synbiotics.

scholarly journals A Novel Membrane Protein, VanJ, Conferring Resistance to Teicoplanin

2012 ◽  
Vol 56 (4) ◽  
pp. 1784-1796 ◽  
Author(s):  
Gabriela Novotna ◽  
Chris Hill ◽  
Karen Vincent ◽  
Chang Liu ◽  
Hee-Jeon Hong
Keyword(s):  
Membrane Protein ◽  
Gene Cluster ◽  
Molecular Mechanisms ◽  
Bacterial Resistance ◽  
Streptomyces Coelicolor ◽  
Biosynthetic Gene Cluster ◽  
Glycopeptide Antibiotics ◽  
Content Type ◽  
Peptidoglycan Biosynthesis ◽  
New Family

ABSTRACTBacterial resistance to the glycopeptide antibiotic teicoplanin shows some important differences from the closely related compound vancomycin. They are currently poorly understood but may reflect significant differences in the mode of action of each antibiotic.Streptomyces coelicolorpossesses avanRSJKHAXgene cluster that when expressed confers resistance to both vancomycin and teicoplanin. The resistance to vancomycin is mediated by the enzymes encoded byvanKHAX, but not byvanJ. vanHAXeffect a reprogramming of peptidoglycan biosynthesis, which is considered to be generic, conferring resistance to all glycopeptide antibiotics. Here, we show thatvanKHAXare not in fact required for teicoplanin resistance inS. coelicolor, which instead is mediated solely byvanJ. vanJis shown to encode a membrane protein oriented with its C-terminal active site exposed to the extracytoplasmic space. VanJ also confers resistance to the teicoplanin-like antibiotics ristocetin and A47934 and to a broad range of semisynthetic teicoplanin derivatives, but not generally to antibiotics or semisynthetic derivatives with vancomycin-like structures.vanJhomologues are found ubiquitously in streptomycetes and includestaPfrom theStreptomyces toyocaensisA47934 biosynthetic gene cluster. While overexpression ofstaPalso conferred resistance to teicoplanin, similar expression of othervanJhomologues (SCO2255, SCO7017, and SAV5946) did not. ThevanJandstaPorthologues, therefore, appear to represent a subset of a larger protein family whose members have acquired specialist roles in antibiotic resistance. Future characterization of the divergent enzymatic activity within this new family will contribute to defining the molecular mechanisms important for teicoplanin activity and resistance.

scholarly journals Glycosulfatase-Encoding Gene Cluster in Bifidobacterium breve UCC2003

2016 ◽  
Vol 82 (22) ◽  
pp. 6611-6623 ◽  
Author(s):  
Muireann Egan ◽  
Hao Jiang ◽  
Mary O'Connell Motherway ◽  
Stefan Oscarson ◽  
Douwe van Sinderen
Keyword(s):  
Gastrointestinal Tract ◽  
Gut Microbiota ◽  
Gene Cluster ◽  
Digestive Tract ◽  
Gene Clusters ◽  
Content Type ◽  
Reading Frame ◽  
Bifidobacterium Breve ◽  
Breastfed Infants ◽  
Encoding Gene

ABSTRACTBifidobacteria constitute a specific group of commensal bacteria typically found in the gastrointestinal tract (GIT) of humans and other mammals.Bifidobacterium brevestrains are numerically prevalent among the gut microbiota of many healthy breastfed infants. In the present study, we investigated glycosulfatase activity in a bacterial isolate from a nursling stool sample,B. breveUCC2003. Two putative sulfatases were identified on the genome ofB. breveUCC2003. The sulfated monosaccharideN-acetylglucosamine-6-sulfate (GlcNAc-6-S) was shown to support the growth ofB. breveUCC2003, whileN-acetylglucosamine-3-sulfate,N-acetylgalactosamine-3-sulfate, andN-acetylgalactosamine-6-sulfate did not support appreciable growth. By using a combination of transcriptomic and functional genomic approaches, a gene cluster designatedats2was shown to be specifically required for GlcNAc-6-S metabolism. Transcription of theats2cluster is regulated by a repressor open reading frame kinase (ROK) family transcriptional repressor. This study represents the first description of glycosulfatase activity within theBifidobacteriumgenus.IMPORTANCEBifidobacteria are saccharolytic organisms naturally found in the digestive tract of mammals and insects.Bifidobacterium brevestrains utilize a variety of plant- and host-derived carbohydrates that allow them to be present as prominent members of the infant gut microbiota as well as being present in the gastrointestinal tract of adults. In this study, we introduce a previously unexplored area of carbohydrate metabolism in bifidobacteria, namely, the metabolism of sulfated carbohydrates.B. breveUCC2003 was shown to metabolizeN-acetylglucosamine-6-sulfate (GlcNAc-6-S) through one of two sulfatase-encoding gene clusters identified on its genome. GlcNAc-6-S can be found in terminal or branched positions of mucin oligosaccharides, the glycoprotein component of the mucous layer that covers the digestive tract. The results of this study provide further evidence of the ability of this species to utilize mucin-derived sugars, a trait which may provide a competitive advantage in both the infant gut and adult gut.

scholarly journals Novel Metabolic Pathway for N-Methylpyrrolidone Degradation in Alicycliphilus sp. Strain BQ1

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Claudia Julieta Solís-González ◽  
Lilianha Domínguez-Malfavón ◽  
Martín Vargas-Suárez ◽  
Itzel Gaytán ◽  
Miguel Ángel Cevallos ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Metabolic Pathway ◽  
Molecular Mechanisms ◽  
Skin Irritation ◽  
Enzymatic Activities ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Content Type ◽  
Semialdehyde Dehydrogenase ◽  
Succinate Semialdehyde

ABSTRACTThe molecular mechanisms underlying the biodegradation ofN-methylpyrrolidone (NMP), a widely used industrial solvent that produces skin irritation in humans and is teratogenic in rats, are unknown.Alicycliphilussp. strain BQ1 degrades NMP. By studying a transposon-tagged mutant unable to degrade NMP, we identified a six-gene cluster (nmpABCDEF) that is transcribed as a polycistronic mRNA and encodes enzymes involved in NMP biodegradation.nmpAand the transposon-affected genenmpBencode anN-methylhydantoin amidohydrolase that transforms NMP to γ-N-methylaminobutyric acid; this is metabolized by an amino acid oxidase (NMPC), either by demethylation to produce γ-aminobutyric acid (GABA) or by deamination to produce succinate semialdehyde (SSA). If GABA is produced, the activity of a GABA aminotransferase (GABA-AT), not encoded in thenmpgene cluster, is needed to generate SSA. SSA is transformed by a succinate semialdehyde dehydrogenase (SSDH) (NMPF) to succinate, which enters the Krebs cycle. The abilities to consume NMP and to utilize it for growth were complemented in the transposon-tagged mutant by use of thenmpABCDgenes. Similarly,Escherichia coliMG1655, which has two SSDHs but is unable to grow in NMP, acquired these abilities after functional complementation with these genes. In wild-type (wt) BQ1 cells growing in NMP, GABA was not detected, but SSA was present at double the amount found in cells growing in Luria-Bertani medium (LB), suggesting that GABA is not an intermediate in this pathway. Moreover,E. coliGABA-AT deletion mutants complemented withnmpABCDgenes retained the ability to grow in NMP, supporting the possibility that γ-N-methylaminobutyric acid is deaminated to SSA instead of being demethylated to GABA.IMPORTANCEN-Methylpyrrolidone is a cyclic amide reported to be biodegradable. However, the metabolic pathway and enzymatic activities for degrading NMP are unknown. By developing molecular biology techniques forAlicycliphilussp. strain BQ1, an environmental bacterium able to grow in NMP, we identified a six-gene cluster encoding enzymatic activities involved in NMP degradation. These findings set the basis for the study of new enzymatic activities and for the development of biotechnological processes with potential applications in bioremediation.

scholarly journals Constitutive Expression of a Nag-Like Dioxygenase Gene through an Internal Promoter in the 2-Chloronitrobenzene Catabolism Gene Cluster of Pseudomonas stutzeri ZWLR2-1

2016 ◽  
Vol 82 (12) ◽  
pp. 3461-3470 ◽  
Author(s):  
Yi-Zhou Gao ◽  
Hong Liu ◽  
Hong-Jun Chao ◽  
Ning-Yi Zhou
Keyword(s):  
Gene Cluster ◽  
Molecular Mechanisms ◽  
Expression System ◽  
Constitutive Expression ◽  
Pseudomonas Stutzeri ◽  
Initial Reaction ◽  
Synthetic Compounds ◽  
Content Type ◽  
Dioxygenase Gene ◽  
Catabolism Pathway

ABSTRACTThe gene cluster encoding the 2-chloronitrobenzene (2CNB) catabolism pathway inPseudomonas stutzeriZWLR2-1 is a patchwork assembly of a Nag-like dioxygenase (dioxygenase belonging to the naphthalene dioxygenase NagAaAbAcAd family fromRalstoniasp. strain U2) gene cluster and a chlorocatechol catabolism cluster. However, the transcriptional regulator gene usually present in the Nag-like dioxygenase gene cluster is missing, leaving it unclear how this cluster is expressed. The pattern of expression of the 2CNB catabolism cluster was investigated here. The results demonstrate that the expression was constitutive and not induced by its substrate 2CNB or salicylate, the usual inducer of expression in the Nag-like dioxygenase family. Reverse transcription-PCR indicated the presence of at least one transcript containing all the structural genes for 2CNB degradation. Among the three promoters verified in the gene cluster, P1 served as the promoter for the entire catabolism operon, but the internal promoters P2 and P3 also enhanced the transcription of the genes downstream. The P3 promoter, which was not previously defined as a promoter sequence, was the strongest of these three promoters. It drove the expression ofcnbAcAdencoding the dioxygenase that catalyzes the initial reaction in the 2CNB catabolism pathway. Bioinformatics and mutation analyses suggested that this P3 promoter evolved through the duplication of an 18-bp fragment and introduction of an extra 132-bp fragment.IMPORTANCEThe release of many synthetic compounds into the environment places selective pressure on bacteria to develop their ability to utilize these chemicals to grow. One of the problems that a bacterium must surmount is to evolve a regulatory device for expression of the corresponding catabolism genes. Considering that 2CNB is a xenobiotic that has existed only since the onset of synthetic chemistry, it may be a good example for studying the molecular mechanisms underlying rapid evolution in regulatory networks for the catabolism of synthetic compounds. The 2CNB utilizerPseudomonas stutzeriZWLR2-1 in this study has adapted itself to the new pollutant by evolving the always-inducible Nag-like dioxygenase into a constitutively expressed enzyme, and its expression has escaped the influence of salicylate. This may facilitate an understanding of how bacteria can rapidly adapt to the new synthetic compounds by evolving its expression system for key enzymes involved in the degradation of a xenobiotic.

scholarly journals 3-Hydroxypyridine Dehydrogenase HpdA Is Encoded by a Novel Four-Component Gene Cluster and Catalyzes the First Step of 3-Hydroxypyridine Catabolism in Ensifer adhaerens HP1

2020 ◽  
Vol 86 (19) ◽  
Author(s):  
Haixia Wang ◽  
Xiaoyu Wang ◽  
Hao Ren ◽  
Xuejun Wang ◽  
Zhenmei Lu
Keyword(s):  
Gene Cluster ◽  
Microbial Degradation ◽  
Molecular Mechanisms ◽  
Gene Clusters ◽  
Pyridine Derivative ◽  
Pyruvate Phosphate Dikinase ◽  
Content Type ◽  
Ensifer Adhaerens ◽  
Microbial Strains ◽  
Important Building Block

ABSTRACT 3-Hydroxypyridine (3HP) is an important natural pyridine derivative. Ensifer adhaerens HP1 can utilize 3HP as its sole sources of carbon, nitrogen, and energy to grow, but the genes responsible for the degradation of 3HP remain unknown. In this study, we predicted that a gene cluster, designated 3hpd, might be responsible for the degradation of 3HP. The analysis showed that the initial hydroxylation of 3HP in E. adhaerens HP1 was catalyzed by a four-component dehydrogenase (HpdA1A2A3A4) and led to the formation of 2,5-dihydroxypyridine (2,5-DHP). In addition, the SRPBCC component in HpdA existed as a separate subunit, which is different from other SRPBCC-containing molybdohydroxylases acting on N-heterocyclic aromatic compounds. Moreover, the results demonstrated that the phosphoenolpyruvate (PEP)-utilizing protein and pyruvate-phosphate dikinase were involved in the HpdA activity, and the presence of the gene cluster 3hpd was discovered in the genomes of diverse microbial strains. Our findings provide a better understanding of the microbial degradation of pyridine derivatives in nature and indicated that further research on the origin of the discovered four-component dehydrogenase with a separate SRPBCC domain and the function of PEP-utilizing protein and pyruvate-phosphate dikinase might be of great significance. IMPORTANCE 3-Hydroxypyridine is an important building block for the synthesis of drugs, herbicides, and antibiotics. Although the microbial degradation of 3-hydroxypyridine has been studied for many years, the molecular mechanisms remain unclear. Here, we show that 3hpd is responsible for the catabolism of 3-hydroxypyridine. The 3hpd gene cluster was found to be widespread in Actinobacteria, Rubrobacteria, Thermoleophilia, and Alpha-, Beta-, and Gammaproteobacteria, and the genetic organization of the 3hpd gene clusters in these bacteria shows high diversity. Our findings provide new insight into the catabolism of 3-hydroxypyridine in bacteria.

scholarly journals Metabolism of Sialic Acid by Bifidobacterium breve UCC2003

2014 ◽  
Vol 80 (14) ◽  
pp. 4414-4426 ◽  
Author(s):  
Muireann Egan ◽  
Mary O'Connell Motherway ◽  
Marco Ventura ◽  
Douwe van Sinderen
Keyword(s):  
Sialic Acid ◽  
Human Milk ◽  
Bifidobacterium Bifidum ◽  
Commensal Bacteria ◽  
Functional Genomic ◽  
Specific Group ◽  
Content Type ◽  
Bifidobacterium Breve ◽  
Human Milk Oligosaccharide ◽  
Uptake And Metabolism

ABSTRACTBifidobacteria constitute a specific group of commensal bacteria that inhabit the gastrointestinal tracts of humans and other mammals.Bifidobacterium breveUCC2003 has previously been shown to utilize several plant-derived carbohydrates that include cellodextrins, starch, and galactan. In the present study, we investigated the ability of this strain to utilize the mucin- and human milk oligosaccharide (HMO)-derived carbohydrate sialic acid. Using a combination of transcriptomic and functional genomic approaches, we identified a gene cluster dedicated to the uptake and metabolism of sialic acid. Furthermore, we demonstrate thatB. breveUCC2003 can cross feed on sialic acid derived from the metabolism of 3′-sialyllactose, an abundant HMO, by another infant gut bifidobacterial strain,Bifidobacterium bifidumPRL2010.

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