Isolation and characterization of 14 additional genes specifying the anaerobic biosynthesis of cobalamin (vitamin B12) in Propionibacterium freudenreichii (P. shermanii) The GenBank accession numbers for the sequences reported in this paper are AY033235, AY033236, U13043 and U51164.

Roessner, Charles A.; Huang, Kai; Warren, Martin J.; Raux, Evelyne; Scott, A. Ian

doi:10.1099/00221287-148-6-1845

Cited by 52 publications

(25 citation statements)

References 37 publications

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“…At 152 bp upstream of the otsA gene, a second ORF was found encoding a protein with 288 aa, with considerable identity with known OtsB proteins (Table 2), and downstream of the otsA gene, a fragment (518 bp) of a third ORF was encountered, which corresponds to part of the gene cbiB encoding cobinamide synthase (Fig. 2a), an enzyme involved in the synthesis of vitamin B 12 (Roessner et al, 2002). Sequencing of the 2.5 kb fragment showed an ORF encoding a protein of 605 aa, with at least 58 % identity with known TreS proteins (Table 2, Fig.…”

Section: Enzyme Activities Involved In Trehalose Metabolismmentioning

confidence: 99%

Biochemical and genetic characterization of the pathways for trehalose metabolism in Propionibacterium freudenreichii, and their role in stress response

2007

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Propionibacterium freudenreichii accumulates high levels of trehalose, especially in response to stress. The pathways for trehalose metabolism were characterized, and their roles in response to osmotic, oxidative and acid stress were studied. Two pathways were identified: the trehalose-6-phosphate synthase/phosphatase (OtsA-OtsB) pathway, and the trehalose synthase (TreS) pathway. The former was used for trehalose synthesis, whereas the latter is proposed to operate in trehalose degradation. The activities of OtsA, OtsB and TreS were detected in cell extracts; the corresponding genes were identified, and the recombinant proteins were characterized in detail. In crude extracts of P. freudenreichii, OtsA was specific for ADP-glucose, in contrast to the pure recombinant OtsA, which used UDP-, GDP-and TDP-glucose, in addition to ADP-glucose. Moreover, the substrate specificity of OtsA in cell extracts was lost during purification, and the recombinant OtsA became specific to ADP-glucose upon incubation with a dialysed cell extract. The level of OtsA was enhanced (approximately twofold) by osmotic, oxidative and acid stress, whereas the level of TreS remained constant, or it decreased, under identical stress conditions. Therefore, the OtsA-OtsB pathway plays an important role in the synthesis of trehalose in response to stress. It is most likely that trehalose degradation proceeds via TreS to yield maltose, which is subsequently catabolized via amylomaltase activity. Hydrolytic activities that are potentially involved in trehalose degradation (trehalase, trehalose phosphorylase, trehalose-6-phosphate phosphorylase and trehalose-6-phosphate hydrolase) were not present. The role of trehalose as a common response to three distinct stresses is discussed.

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Section: Enzyme Activities Involved In Trehalose Metabolismmentioning

confidence: 99%

Biochemical and genetic characterization of the pathways for trehalose metabolism in Propionibacterium freudenreichii, and their role in stress response

2007

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“…Vitamin B 12 is a type of cobalt corrinoid, particularly of the cobalamin group and is solely synthesised by some bacteria and archea. Vitamin B 12 biosynthesis was first identified in Propionibacteria freudenreichii, now used in the commercial production of the vitamin (101) . Furthermore, Lactobacillus reuteri CRL1098 was shown to be the first lactic acid producing bacterial strain capable of producing a cobalamin-like compound with an absorption spectrum resembling that of standard cobalamin (102) .…”

Section: Vitamin Synthesismentioning

confidence: 99%

Gut microbiota, the pharmabiotics they produce and host health

et al. 2014

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A healthy gut microbiota plays many crucial functions in the host, being involved in the correct development and functioning of the immune system, assisting in the digestion of certain foods and in the production of health-beneficial bioactive metabolites or ‘pharmabiotics’. These include bioactive lipids (including SCFA and conjugated linoleic acid) antimicrobials and exopolysaccharides in addition to nutrients, including vitamins B and K. Alterations in the composition of the gut microbiota and reductions in microbial diversity are highlighted in many disease states, possibly rendering the host susceptible to infection and consequently negatively affecting innate immune function. Evidence is also emerging of microbially produced molecules with neuroactive functions that can have influences across the brain–gut axis. For example, γ-aminobutyric acid, serotonin, catecholamines and acetylcholine may modulate neural signalling within the enteric nervous system, when released in the intestinal lumen and consequently signal brain function and behaviour. Dietary supplementation with probiotics and prebiotics are the most widely used dietary adjuncts to modulate the gut microbiota. Furthermore, evidence is emerging of the interactions between administered microbes and dietary substrates, leading to the production of pharmabiotics, which may directly or indirectly positively influence human health.

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“…Survival in this unstable environment requires a wide range of rapid, adaptive responses which are triggered by regulatory proteins. These regulators respond to specific environmental and cellular signals that modulate transcription, translation, or some other event in gene expression, so that the physiological responses are modified appropriately (32,52,64,104,107,145,244,311,312,326,330,379,397,409,427).…”

Section: Introductionmentioning

confidence: 99%

The TetR Family of Transcriptional Repressors

Ramos

Martínez-Bueno

Molina‐Henares

et al. 2005

Microbiol Mol Biol Rev

980

1,133

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We have developed a general profile for the proteins of the TetR family of repressors. The stretch that best defines the profile of this family is made up of 47 amino acid residues that correspond to the helix-turn-helix DNA binding motif and adjacent regions in the three-dimensional structures of TetR, QacR, CprB, and EthR, four family members for which the function and three-dimensional structure are known. We have detected a set of 2,353 nonredundant proteins belonging to this family by screening genome and protein databases with the TetR profile. Proteins of the TetR family have been found in 115 genera of gram-positive, α-, β-, and γ-proteobacteria, cyanobacteria, and archaea. The set of genes they regulate is known for 85 out of the 2,353 members of the family. These proteins are involved in the transcriptional control of multidrug efflux pumps, pathways for the biosynthesis of antibiotics, response to osmotic stress and toxic chemicals, control of catabolic pathways, differentiation processes, and pathogenicity. The regulatory network in which the family member is involved can be simple, as in TetR (i.e., TetR bound to the target operator represses tetA transcription and is released in the presence of tetracycline), or more complex, involving a series of regulatory cascades in which either the expression of the TetR family member is modulated by another regulator or the TetR family member triggers a cell response to react to environmental insults. Based on what has been learned from the cocrystals of TetR and QacR with their target operators and from their three-dimensional structures in the absence and in the presence of ligands, and based on multialignment analyses of the conserved stretch of 47 amino acids in the 2,353 TetR family members, two groups of residues have been identified. One group includes highly conserved positions involved in the proper orientation of the helix-turn-helix motif and hence seems to play a structural role. The other set of less conserved residues are involved in establishing contacts with the phosphate backbone and target bases in the operator. Information related to the TetR family of regulators has been updated in a database that can be accessed at www.bactregulators.org

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Isolation and characterization of 14 additional genes specifying the anaerobic biosynthesis of cobalamin (vitamin B12) in Propionibacterium freudenreichii (P. shermanii) The GenBank accession numbers for the sequences reported in this paper are AY033235, AY033236, U13043 and U51164.

Cited by 52 publications

References 37 publications

Biochemical and genetic characterization of the pathways for trehalose metabolism in Propionibacterium freudenreichii, and their role in stress response

Biochemical and genetic characterization of the pathways for trehalose metabolism in Propionibacterium freudenreichii, and their role in stress response

Gut microbiota, the pharmabiotics they produce and host health

The TetR Family of Transcriptional Repressors

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