Trans‐methylation reactions in plants: focus on the activated methyl cycle

2017 ◽  
Vol 162 (2) ◽  
pp. 162-176 ◽  
Author(s):  
Moona Rahikainen ◽  
Sara Alegre ◽  
Andrea Trotta ◽  
Jesús Pascual ◽  
Saijaliisa Kangasjärvi
Keyword(s):  
Methyl Cycle

scholarly journals Quantitative Effect of luxS Gene Inactivation on the Fitness of Helicobacter pylori

2006 ◽  
Vol 72 (10) ◽  
pp. 6615-6622 ◽  
Author(s):  
Woo-Kon Lee ◽  
Keiji Ogura ◽  
John T. Loh ◽  
Timothy L. Cover ◽  
Douglas E. Berg
Keyword(s):  
Helicobacter Pylori ◽  
Competitive Ability ◽  
Reference Strain ◽  
Bacterial Species ◽  
Soft Agar ◽  
Autoinducer 2 ◽  
Methyl Cycle ◽  
Adenosyl Methionine ◽  
Unrelated Strain ◽  
H Pylori

ABSTRACT Furanone metabolites called AI-2 (autoinducer 2), used by some bacterial species for signaling and cell density-regulated changes in gene expression, are made while regenerating S-adenosyl methionine (SAM) after its use as a methyl donor. The luxS-encoded enzyme, in particular, participates in this activated methyl cycle by generating both a pentanedione, which is transformed chemically into these AI-2 compounds, and homocysteine, a precursor of methionine and SAM. Helicobacter pylori seems to contain the genes for this activated methyl cycle, including luxS, but not genes for AI-2 uptake and transcriptional regulation. Here we report that deletion of luxS in H. pylori reference strain SS1 diminished its competitive ability in mice and motility in soft agar, whereas no such effect was seen with an equivalent ΔluxS derivative of the unrelated strain X47. These different outcomes are consistent with H. pylori's considerable genetic diversity and are reminiscent of phenotypes seen after deletion of another nonessential metabolic gene, that encoding polyphosphate kinase 1. We suggest that synthesis of AI-2 by H. pylori may be an inadvertent consequence of metabolite flux in its activated methyl cycle and that impairment of this cycle and/or pathways affected by it, rather than loss of quorum sensing, is deleterious for some H. pylori strains. Also tenable is a model in which AI-2 affects other microbes in H. pylori's gastric ecosystem and thereby modulates the gastric environment in ways to which certain H. pylori strains are particularly sensitive.

Maternal Methyl-Cycle Amino Acid Profile and Kinetics: Relation with Placental Growth

2017 ◽  
Vol 54 (2) ◽  
pp. 118
Author(s):  
Sarita Devi ◽  
Julian Crasta ◽  
Tinku Thomas ◽  
Pratibha Dwarkanath ◽  
Annamma Thomas ◽  
...  
Keyword(s):  
Amino Acid ◽  
Pregnant Women ◽  
Fetal Growth ◽  
Secondary Analysis ◽  
Placental Development ◽  
Amino Acid Availability ◽  
South Indian ◽  
Methyl Cycle ◽  
And Function ◽  
Amino Acid Concentrations

Maternal intake of quality protein regulates placental development and function thereby affecting fetal growth. Considering the prevalence of inadequate intakes of quality protein in Indian pregnant women, understanding the interplay between maternal supply of protein, its metabolism and fetoplacental growth becomes important. A secondary analysis of data from an open labelled-randomized intervention trial with 500 ml milk/day on south Indian pregnant women with marginally low vitamin B12 status, was performed to assess the relations between placental parameters and maternal trimester 3 methyl-cycle amino acid status as well as kinetics. This analysis was performed for 42 pregnancies from the trial where placentae had been collected and placental parameters had been measured. For these pregnancies, data on trimester 3 methionine, serine and glycine kinetics as well as plasma free amino acid concentrations were available. Protein intake and plasma citrulline concentrations were positively correlated at trimester 3 (ρ = 0.34, P = 0.027). Placental weight correlated positively with methyl-cycle specific amino acid concentrations [methionine (ρ = 0.32, P = 0.0388), serine (ρ = 0.49, P = 0.0009)], methionine kinetics [total methionine flux rates (ρ = 0.42, P = 0.006), RM (ρ = 0.45, P = 0.003), TS (ρ = 0.32, P = 0.046), TM (ρ = 0.45, P = 0.004)] and with birth weight (ρ = 0.57, P < 0.001). Findings from the current study indicate that maternal amino acid availability and more importantly, maternal methionine kinetics, positively influenced placental growth, likely mediated by key amino acids such as citrulline, which is known to regulate placental blood flow and function. As an appropriately functioning placenta is indispensable for fetal growth, these findings will form the basis for detailed mechanistic explorations into the placental regulation of maternal supply of amino acid to the fetus for designing effective intervention strategies towards optimizing fetomaternal health during and after pregnancy.

Effect of Increased Dietary Protein on the Plasma Methyl-Cycle Amino Acid Profile and Kinetics during Pregnancy

2016 ◽  
Vol 53 (4) ◽  
pp. 380
Author(s):  
Sarita Devi ◽  
Tinku Thomas ◽  
Pratibha Dwarkanath ◽  
Annamma Thomas ◽  
C. N. Sheela ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dietary Protein ◽  
Protein Intake ◽  
Plasma Concentrations ◽  
Small Sample ◽  
Dietary Protein Intake ◽  
Flux Rate ◽  
Conversion Rates ◽  
Methyl Cycle

Low intakes of quality dietary protein could affect the methionine cycle during pregnancy, which is important for fetal growth and epigenetic regulations. Since low quality protein intake is prevalent in India, it is important to define biomarkers of the low protein intake, specifically of methyl cycle homeostasis. A secondary analysis of data was performed, from a randomized intervention trial with 500 ml milk/d on south Indian pregnant women, to examine the association of dietary protein intake with concentrations of specific amino acids (methionine, glycine and serine). The subjects also underwent isotopic infusions (n = 52) for the measurement of amino acid kinetics. Dietary intakes were measured each week by multiple 24 h recall until delivery. The plasma concentrations of amino acids (methionine, serine and glycine) were compared with kinetics of methionine i.e. transmethylation, remethylation and transulfuration (TM, RM, TS) and serine to glycine conversion rates, as measured by stable isotope labeled amino acid infusion. Dietary protein intake in the 3<sup>rd</sup> trimester correlated positively with intakes of milk and milk based food products (ρ=0.52, p&lt;0.001) and methionine (ρ=0.97, p&lt;0.001) and with gestational weight gain (GWG, ρ=0.32, p=0.044). While the methionine concentration did not correlate with methyl cycle flux parameters (TM, RM and TS), the plasma concentrations of conditionally essential serine and glycine were positively correlated with their respective flux rate and with RM, TM and TS rates. Further, glycine concentrations specifically correlated positively with serine to glycine conversion rates (ρ=0.32, p=0.027). Dietary protein and methionine supply are important for the conservation of methionine during pregnancy. This had an effect on GWG, but not on birth weight, though this may have been due to the relatively small sample size. The plasma concentration of glycine was correlated with the serine-glycine conversion, which affords methyl groups for the body and supplies these when dietary protein/methionine is in poor supply. This indicates that itcan act as a biomarker of the serine-glycine conversion flux rate, which increases in the presence of a poor protein supply. In general, the plasma concentrations of these conditionally essential amino acids may be biomarkers of the methyl cycle during pregnancy, but this needs to be tested in a larger sample.

Cell-Free Preparations of Lactobacillus acidophilus Strain La-5 and Bifidobacterium longum Strain NCC2705 Affect Virulence Gene Expression in Campylobacter jejuni

2013 ◽  
Vol 76 (10) ◽  
pp. 1740-1746 ◽  
Author(s):  
A. MUNDI ◽  
V. DELCENSERIE ◽  
M. AMIRI-JAMI ◽  
S. MOORHEAD ◽  
M. W. GRIFFITHS
Keyword(s):  
Campylobacter Jejuni ◽  
Lactobacillus Acidophilus ◽  
Diarrheal Disease ◽  
Bifidobacterium Longum ◽  
Virulence Gene ◽  
Active Role ◽  
Inhibitory Effect ◽  
Virulence Gene Expression ◽  
Luxs Mutant ◽  
Methyl Cycle

Campylobacter spp. are among the most commonly reported bacterial causes of acute diarrheal disease in humans worldwide. Potential virulence factors include motility, chemotaxis, colonization ability, adhesion to intestinal cells, invasion and epithelial translocation, intracellular survival, and formation of toxins. Probiotic Lactobacillus and Bifidobacterium strains are known to have an inhibitory effect against the growth of various foodborne pathogens. The objective of this study was to investigate the effect of Lactobacillus acidophilus strain La-5 and Bifidobacterium longum strain NCC2705 cell-free spent media (CFSM) on the expression of virulence genes (cadF, cdtB, flaA, and ciaB) of Campylobacter jejuni strain 81-176 and a luxS mutant, using real-time PCR. Our results demonstrated that the CFSM of both probiotic strains were able to down-regulate the expression of ciaB (ratio of −2.80 and −5.51, respectively) and flaA (ratio of −7.00 and −5.13, respectively) in the wild-type Campylobacter strain. In the luxS mutant, where the activated methyl cycle is disrupted, only the ciaB gene (ratio −7.21) was repressed in the presence of La-5 CFSM. A supplementation of homocysteine to restore the disrupted cycle was able to partially reestablish the probiotic effect of both strains. luxS and the activated methyl cycle might play an active role in the modulation of virulence of C. jejuni by probiotic extracts.

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