TY - JOUR
T1 - Microbial Metabolic Capacity for Intestinal Folate Production and Modulation of Host Folate Receptors
AU - Engevik, Melinda A.
AU - Morra, Christina N.
AU - Röth, Daniel
AU - Engevik, Kristen
AU - Spinler, Jennifer K.
AU - Devaraj, Sridevi
AU - Crawford, Sue E.
AU - Estes, Mary K.
AU - Kalkum, Markus
AU - Versalovic, James
N1 - Funding Information:
We would like to thank Dr. Xi-Lei Zeng for expertise and preparation of the enteroid monolayers used in this study. Funding. This study was supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases (Grant P30-DK-56338 to Texas Medical Center ? Digestive Disease Center, Gastrointestinal Experimental Model Systems), the National Cancer Institute (Grant U01-CA-170930 to JV), and unrestricted research support from the BioGaia AB (to JV). The Mass Spectrometry & Proteomics Core Facility of the City of Hope was supported in parts by the National Cancer Institute of the National Institutes of Health under award number P30CA033572.
Publisher Copyright:
© Copyright © 2019 Engevik, Morra, Röth, Engevik, Spinler, Devaraj, Crawford, Estes, Kalkum and Versalovic.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
PY - 2019/10/9
Y1 - 2019/10/9
N2 - Microbial metabolites, including B complex vitamins contribute to diverse aspects of human health. Folate, or vitamin B9, refers to a broad category of biomolecules that include pterin, para-aminobenzoic acid (pABA), and glutamate subunits. Folates are required for DNA synthesis and epigenetic regulation. In addition to dietary nutrients, the gut microbiota has been recognized as a source of B complex vitamins, including folate. This study evaluated the predicted folate synthesis capabilities in the genomes of human commensal microbes identified in the Human Microbiome Project and folate production by representative strains of six human intestinal bacterial phyla. Bacterial folate synthesis genes were ubiquitous across 512 gastrointestinal reference genomes with 13% of the genomes containing all genes required for complete de novo folate synthesis. An additional 39% of the genomes had the genetic capacity to synthesize folates in the presence of pABA, an upstream intermediate that can be obtained through diet or from other intestinal microbes. Bacterial folate synthesis was assessed during exponential and stationary phase growth through the evaluation of expression of select folate synthesis genes, quantification of total folate production, and analysis of folate polyglutamylation. Increased expression of key folate synthesis genes was apparent in exponential phase, and increased folate polyglutamylation occurred during late stationary phase. Of the folate producers, we focused on the commensal Lactobacillus reuteri to examine host–microbe interactions in relation to folate and examined folate receptors in the physiologically relevant human enteroid model. RNAseq data revealed segment-specific folate receptor distribution. Treatment of human colonoid monolayers with conditioned media (CM) from wild-type L. reuteri did not influence the expression of key folate transporters proton-coupled folate transporter (PCFT) or reduced folate carrier (RFC). However, CM from L. reuteri containing a site-specific inactivation of the folC gene, which prevents the bacteria from synthesizing a polyglutamate tail on folate, significantly upregulated RFC expression. No effects were observed using L. reuteri with a site inactivation of folC2, which results in no folate production. This work sheds light on the contributions of microbial folate to overall folate status and mammalian host metabolism.
AB - Microbial metabolites, including B complex vitamins contribute to diverse aspects of human health. Folate, or vitamin B9, refers to a broad category of biomolecules that include pterin, para-aminobenzoic acid (pABA), and glutamate subunits. Folates are required for DNA synthesis and epigenetic regulation. In addition to dietary nutrients, the gut microbiota has been recognized as a source of B complex vitamins, including folate. This study evaluated the predicted folate synthesis capabilities in the genomes of human commensal microbes identified in the Human Microbiome Project and folate production by representative strains of six human intestinal bacterial phyla. Bacterial folate synthesis genes were ubiquitous across 512 gastrointestinal reference genomes with 13% of the genomes containing all genes required for complete de novo folate synthesis. An additional 39% of the genomes had the genetic capacity to synthesize folates in the presence of pABA, an upstream intermediate that can be obtained through diet or from other intestinal microbes. Bacterial folate synthesis was assessed during exponential and stationary phase growth through the evaluation of expression of select folate synthesis genes, quantification of total folate production, and analysis of folate polyglutamylation. Increased expression of key folate synthesis genes was apparent in exponential phase, and increased folate polyglutamylation occurred during late stationary phase. Of the folate producers, we focused on the commensal Lactobacillus reuteri to examine host–microbe interactions in relation to folate and examined folate receptors in the physiologically relevant human enteroid model. RNAseq data revealed segment-specific folate receptor distribution. Treatment of human colonoid monolayers with conditioned media (CM) from wild-type L. reuteri did not influence the expression of key folate transporters proton-coupled folate transporter (PCFT) or reduced folate carrier (RFC). However, CM from L. reuteri containing a site-specific inactivation of the folC gene, which prevents the bacteria from synthesizing a polyglutamate tail on folate, significantly upregulated RFC expression. No effects were observed using L. reuteri with a site inactivation of folC2, which results in no folate production. This work sheds light on the contributions of microbial folate to overall folate status and mammalian host metabolism.
KW - B vitamin
KW - Lactobacilli
KW - Lactobacillus reuteri
KW - enteroids
KW - folate transporters
KW - folylpolyglutamate
KW - microbiome
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U2 - 10.3389/fmicb.2019.02305
DO - 10.3389/fmicb.2019.02305
M3 - Article
AN - SCOPUS:85074175085
VL - 10
JO - Frontiers in Microbiology
JF - Frontiers in Microbiology
M1 - 2305
ER -