N-Acetyl-D-mannosamine

Integrative analysis with microbial modelling and machine learning uncovers potential alleviators for ulcerative colitis.[Pubmed:38563656]

Gut Microbes. 2024 Jan-Dec;16(1):2336877.

Ulcerative colitis (UC) is a challenging form of inflammatory bowel disease, and its etiology is intricately linked to disturbances in the gut microbiome. To identify the potential alleviators of UC, we employed an integrative analysis combining microbial community modeling with advanced machine learning techniques. Using metagenomics data sourced from the Integrated Human Microbiome Project, we constructed individualized microbiome community models for each participant. Our analysis highlighted a significant decline in both alpha and beta-diversity of strain-level microbial populations in UC subjects compared to controls. Distinct differences were also observed in the predicted fecal metabolite profiles and strain-to-metabolite contributions between the two groups. Using tree-based machine learning models, we successfully identified specific microbial strains and their associated metabolites as potential alleviators of UC. Notably, our experimental validation using a dextran sulfate sodium-induced UC mouse model demonstrated that the administration of Parabacteroides merdae ATCC 43,184 and N-Acetyl-D-mannosamine provided notable relief from colitis symptoms. In summary, our study underscores the potential of an integrative approach to identify novel therapeutic avenues for UC, paving the way for future targeted interventions.

Biosynthesis of UDP-alpha-N-Acetyl-d-mannosaminuronic Acid and CMP-beta-N-Acetyl-d-neuraminic Acid for the Capsular Polysaccharides of Campylobacter jejuni.[Pubmed:38382015]

Biochemistry. 2024 Mar 5;63(5):688-698.

Campylobacter jejuni is a human pathogen and a leading cause of food poisoning in North America and Europe. The exterior surface of the bacterial cell wall is attached to a polymeric coat of sugar molecules known as the capsular polysaccharide (CPS) that helps protect the organism from the host immune response. The CPS is composed of a repeating sequence of common and unusual sugar residues. In the HS:11 serotype of C. jejuni, we identified two enzymes in the gene cluster for CPS formation that are utilized for the biosynthesis of UDP-alpha-N-acetyl-d-mannosaminuronic acid (UDP-ManNAcA). In the first step, UDP-alpha-N-acetyl-d-glucosamine (UDP-GlcNAc) is epimerized at C2 to form UDP-alpha-N-Acetyl-D-mannosamine (UDP-ManNAc). This product is then oxidized by a NAD(+)-dependent C6-dehydrogenase to form UDP-ManNAcA. In the HS:6 serotype (C. jejuni strain 81116), we identified three enzymes that are required for the biosynthesis of CMP-beta-N-acetyl-d-neuraminic acid (CMP-Neu5Ac). In the first step, UDP-GlcNAc is epimerized at C2 and subsequently hydrolyzed to form N-Acetyl-D-mannosamine (ManNAc) with the release of UDP. This product is then condensed with PEP by N-acetyl-d-neuraminate synthase to form N-acetyl-d-neuraminic acid (Neu5Ac). In the final step, CMP-N-acetyl-d-neuraminic acid synthase utilizes CTP to convert this product into CMP-Neu5Ac. A bioinformatic analysis of these five enzymes from C. jejuni serotypes HS:11 and HS:6 identified other bacterial species that can produce UDP-ManNAcA or CMP-Neu5Ac for CPS formation.

Recent studies on non-invasive biomarkers useful in biliary atresia - a literature review.[Pubmed:37717264]

Acta Biochim Pol. 2023 Sep 17;70(3):475-480.

The aim of this review is to specify new potential reliable and non-invasive methods for the diagnosis of biliary atresia (BA) that could shorten the way to diagnose BA, and finally the surgical treatment. Apart from the biomarkers that have been proven helpful and are used nowadays in neonatal wards, there are several new potential biomarkers that researchers have found to be helpful in the diagnosis of biliary atresia. Circulating microRNAs, matrix metalloproteinase-7, stool proteins, interleukin-33, Th17-associated cytokines, urinary metabolomics, anti-smooth muscle antibodies, heat shock proteins 90 and positive biliary epithelial cells CD56 are among those presented in this summary. These markers may play a new significant role in BA diagnosis. The described methods include Nomogram, Circulating microRNAs (miRNAs), Matrix metalloproteinase-7 (MMP-7), Stool proteins, Interleukin-33 (IL-33), Th17-associated cytokines, Alpha-aminoadipic acid and N-Acetyl-D-mannosamine in urine, Anti-smooth muscle antibodies (ASMA), Heat shock proteins 90 (HSP90), Positive biliary epithelial cells CD56.

Escherichia coli BL21(DE3) optimized deletion mutant as the host for whole-cell biotransformation of N‑acetyl‑D‑neuraminic acid.[Pubmed:37688676]

Biotechnol Lett. 2023 Dec;45(11-12):1521-1528.

N‑Acetyl‑D‑neuraminic acid (Neu5Ac) is the crucial compound for the chemical synthesis of antiflu medicine Zanamivir. Chemoenzymatic synthesis of Neu5Ac involves N-acetyl-D-glucosamine 2-epimerase (AGE)-catalyzed epimerization of N-acetyl-D-glucosamine (GlcNAc) to N-Acetyl-D-mannosamine (ManNAc), and aldolase-catalyzed condensation between ManNAc and pyruvate. Host optimization plays an important role in the whole-cell biotransformation of value-added compounds. In this study, via single-plasmid biotransformation system, we showed that the AGE gene BT0453, cloned from human gut microorganism Bacteroides thetaiotaomicron VPI-5482, showed the highest biotransformation yield among the AGE genes tested; and there is no clear Neu5Ac yield difference between the BT0453 coupled with one aldolase coding nanA gene and two nanA genes. Next, Escherichia coli chromosomal genes involved in substrate degradation, product exportation and pH change were deleted via recombineering and CRISPR/Cas9. With the final E. coli BL21(DE3) DeltananA Deltanag DeltapoxB as host, a significant 16.5% yield improvement was obtained. Furthermore, precursor (pyruvate) feeding resulted in 3.2% yield improvement, reaching 66.8% molar biotransformation. The result highlights the importance of host optimization, and set the stage for further metabolic engineering of whole-cell biotransformation of Neu5Ac.