What's the relationship between tryptophan and niacin? | Yahoo Answers
A naturally occurring vitamin B complex, Niacin (nicotinic acid), is a and tryptophan metabolism into nicotinate D-ribonucleotide (Kanehisa et al., ). (Baerends et al., ) and a MEME motif sampler search (Bailey and Elkan, ). . the absence of any commercial or financial relationships that could be construed. also involved in the biosynthesis of niacin-containing coenzymes from tryptophan via FAD- .. Relationships between micronutrient intake and biochemical des tissues de la ratte en lactation et des jeunes en ces memes. Specifically, L-tryptophan, an essential amino acid that our livers synthesize into niacin. Niacin, in turn, helps create the neurotransmitter.
NiaR-dependent regulation of niaX, nadC, and pnuC is further confirmed by promoter lacZ-fusion studies. Introduction Bacteria can trigger transcriptional and phenotypic programs to synchronize an adaptive response in reaction to environmental fluctuations or stresses Edwards et al. This not only relies on the number of virulence factors it possesses, but also on the proper use of nutrients available in the human niches Phillips et al.
A number of important vitamins and co-factors are required by bacteria to survive and grow successfully. Streptococcus pneumoniae, a major Gram-positive human pathogen and nasopharyngeal colonizer, encounters different environmental factors and has to fine-tune its gene expression accordingly Bogaert et al.
Niacin - Wikipedia
Niacin nicotinic acida naturally occurring vitamin B complex, is a precursor of coenzymes NAD and NADP, and plays an important role in electron transfer during metabolic processes Wei et al. Niacin has long been used for the treatment of lipid disorders and cardiovascular disease Wei et al. It can regulate the activity of microbial two-component systems and, subsequently, modulate the genes and phenotypes that are controlled by these regulatory proteins McPheat et al.
Particularly, niacin has been reported to repress the expression of many genes including virulence factors in Bordetella pertussis, such as pertussis toxin, adenylate cyclase toxin, and filamentous hemagglutinin Schneider and Parker, ; McPheat et al. It has been proposed that in S. Nicotinate mononucleotide is then converted to nicotinic acid adenine dinucleotide by NadD, whereafter NadE converts nicotinic acid adenine dinucleotide to nicotine adenine dinucleotide NAD Johnson et al.
Another important enzyme glyceraldehydephosphate dehydrogenase GAP is a highly conserved and a multifunctional protein with significant activity in several fundamental cell pathways Sirover, Usually, the dehydrogenase reactions of metabolic pathways have been deemed the major sources of NADPH. Nevertheless, the importance of transhydrogenases, glucose dehydrogenases, and non-phosphorylating glyceraldehyde 3- phosphate dehydrogenase GAPNis becoming eminent, suggesting that the traditional view is over-simplistic Sauer U.
Furthermore, several cellular processes in bacterial and mammalian cells also use NAD, for instance DNA ligation and repair, redox recycling in the pyruvate dehydrogenase pathway, and synthesis of acetyl-CoA for the tricarboxylic acid cycle Ishino et al. The NiaR regulon is not limited to the transcriptional regulation of the nadABC but in some species it also covers niacin salvage the pncAB genes and contains uncharacterized membrane proteins putatively involved in niacin transport Rodionov et al.
Moreover, members of the NiaP family involved in niacin uptake are not only conserved in bacteria but also in multicellular eukaryotes, including humans, suggesting the putative involvement of NiaP in niacin utilization in these organisms Rodionov et al. This study explains the transcriptomic response of S. We established that the transcriptional regulator NiaR acts as a transcriptional repressor for niaX, pnuC, and nadC genes involved in niacin uptake and utilization.
CDM was prepared without niacin. For selection on antibiotics, media were supplemented with the following concentrations of antibiotics: Primers used in this study are based on the sequence of the S.
List of strains and plasmids used in this study. List of primers used in this study. Then, by restriction and ligation, the left and right flanking regions of niaR were fused to the spectinomycin-resistance gene.
The resulting ligation products were transformed to S.
Nutritional Aspect of Tryptophan Metabolism
These constructs were introduced into the S. These constructs were further introduced into D39 wild-type resulting in strains MA, respectively. Microarray Analysis Microarray analysis was performed as described before Afzal et al. For DNA microarray analysis of S. The procedures for DNA microarray analysis were performed as described previously Afzal et al.
Results Niacin-dependent Gene Regulation in S. A particular gene cluster spd was significantly upregulated in the absence of niacin. This gene cluster codes for three hypothetical proteins, which are putative membrane proteins. Another gene cluster spd was significantly upregulated in the absence of niacin.
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- What's the relationship between tryptophan and niacin?
This gene cluster consists of a DNA-binding response regulator encoded by spda sensor histidine kinase encoded by spdtwo hypothetical proteins encoded by spd and spd and an ABC transporter encoded by spd Some genes that appear to be a part of a gene cluster were also downregulated under our tested conditions spd and spd All of these genes code for hypothetical proteins and the role of these genes warrants further investigation. Summary of the transcriptome comparison of S.
Putative niacin biosynthesis pathway genes were significantly upregulated in the absence of niacin fba, rex, gapN, niaX, pncB-nadE, pnuC, gap, spd, nadC, adhE, and adhB2. NiaX encoded by niaX is a substrate-specific component predicted niacin ECF transporter, whereas PnuC encoded by pnuC is a ribosyl nicotinamide transporter. NadC encoded by nadC is a nicotinate-nucleotide pyrophosphorylase and has been proposed to convert quinolinate formed from alanine, aspartate, and glutamate, and tryptophan metabolism into nicotinate D-ribonucleotide Kanehisa et al.
These data further confirm our microarray data described above and suggest the role of niacin in the regulation of these genes.Professional Supplement Review - Niacin
Standard deviations of three independent experiments are indicated in bars. NiaR was first studied in B. Therefore, we decided to further study the role of NiaR in the regulation of these genes. A deletion mutant of the niaR gene was constructed and microarray comparison of S. Table 4 summarizes the transcriptome changes induced by the deletion of niaR in S. Expression of spd and spd coding for hypothetical proteins was also upregulated. The resultant nicotinamide is distributed to non-hepatic tissues.
We have studied the effects of changes in tryptophan—nicotinamide metabolism on niacin nutritional status. The liver plays a critical role in nicotinamide supply. Animal studies showed that the tryptophan—nicotinamide pathway is affected by physiological conditions, the presence of disease, nutrients, hormones, and chemicals.
Human studies have shown that 1 mg of nicotinamide is produced from 67 mg of tryptophan intake, and that the conversion ratio of tryptophan to nicotinamide is enhanced from mid to late pregnancy. These findings have contributed to the determination of dietary reference intakes for niacin recommended in the Dietary Reference Intakes for Japanese Our findings suggest that the conversion of nicotinamide from tryptophan is important in maintaining niacin nutrition. The only route by which nicotinamide is biosynthesized is from tryptophan.
Niacin deficiency leads to pellagra, the typical symptoms of which are diarrhea, dermatitis, dementia, and death. Pellagra was common in the United States and parts of Europe in the early 20th century among people consuming foods containing low levels of niacin and tryptophan, such as corn.