Pen and Pal are nucleotide-sugar dehydratases that convert UDP-GlcNAc to UDP-6-deoxy-D-GlcNAc-5,6-ene and then to UDP-4-keto-6-deoxy-L-AltNAc for CMP-pseudaminic acid synthesis in Bacillus thuringiensis

Discovery of a Monoclonal Antibody That Targets Cell-Surface Pseudaminic Acid of Acinetobacter baumannii with Direct Bactericidal Effect

The therapeutic effects of antibodies include neutralization of pathogens, activation of the host complement system, and facilitation of phagocytosis of pathogens. However, antibody alone has never been shown to exhibit bactericidal activity. In this study, we developed a monoclonal antibody that targets the bacterial cell surface component Pseudaminic acid (Pse). This monoclonal antibody, Pse-MAB1, exhibited direct bactericidal activity on Acinetobacter baumannii strains, even in the absence of the host complements or other immune factors, and was able to confer a protective effect against A. baumannii infections in mice. This study provides new insight into the potential of developing monoclonal antibody-based antimicrobial therapy of multidrug resistant bacterial infections, especially those which occurred among immunocompromised patients.

Selective Biocatalytic Defunctionalization of Raw Materials

Biobased raw materials, such as carbohydrates, amino acids, nucleotides, or lipids contain valuable functional groups with oxygen and nitrogen atoms. An abundance of many functional groups of the same type, such as primary or secondary hydroxy groups in carbohydrates, however, limits the synthetic usefulness if similar reactivities cannot be differentiated. Therefore, selective defunctionalization of highly functionalized biobased starting materials to differentially functionalized compounds can provide a sustainable access to chiral synthons, even in case of products with fewer functional groups. Selective defunctionalization reactions, without affecting other functional groups of the same type, are of fundamental interest for biocatalytic reactions. Controlled biocatalytic defunctionalizations of biobased raw materials are attractive for obtaining valuable platform chemicals and building blocks. The biocatalytic removal of functional groups, an important feature of natural metabolic pathways, can also be utilized in a systemic strategy for sustainable metabolite synthesis.

Nucleotide sugar dehydratases: Structure, mechanism, substrate specificity, and application potential

Nucleotide sugar (NS) dehydratases play a central role in the biosynthesis of deoxy and amino sugars, which are involved in a variety of biological functions in all domains of life. Bacteria are true masters of deoxy sugar biosynthesis as they can produce a wide range of highly specialized monosaccharides. Indeed, deoxy and amino sugars play important roles in the virulence of gram-positive and gram-negative pathogenic species and are additionally involved in the biosynthesis of diverse macrolide antibiotics. The biosynthesis of deoxy sugars relies on the activity of NS dehydratases, which can be subdivided into three groups based on their structure and reaction mechanism. The best-characterized NS dehydratases are the 4,6-dehydratases that, together with the 5,6-dehydratases, belong to the NS-short-chain dehydrogenase/reductase superfamily. The other two groups are the less abundant 2,3-dehydratases that belong to the Nudix hydrolase superfamily and 3-dehydratases, which are related to aspartame aminotransferases. 4,6-Dehydratases catalyze the first step in all deoxy sugar biosynthesis pathways, converting nucleoside diphosphate hexoses to nucleoside diphosphate-4-keto-6-deoxy hexoses, which in turn are further deoxygenated by the 2,3- and 3-dehydratases to form dideoxy and trideoxy sugars. In this review, we give an overview of the NS dehydratases focusing on the comparison of their structure and reaction mechanisms, thereby highlighting common features, and investigating differences between closely related members of the same superfamilies.

Biosynthesis of the nucleoside antibiotic angustmycins: identification and characterization of the biosynthetic gene cluster reveal unprecedented dehydratase required for exo-glycal formation

The nucleoside antibiotic angustmycin, produced by some Streptomyces strains, is composed of adenine and C₆ sugar and shows antibiotic and antitumor activities. In this study, we propose a biosynthetic pathway for angustmycin using a heterologous expression experiment coupled with in silico analysis of the angustmycin biosynthetic gene (agm) cluster. The biochemical characterization of Agm6 demonstrated its role in angustmycin biosynthesis as an unprecedented dehydratase.

Biosynthesis of UDP-2-acetamido-4-formamido-2,4,6-trideoxy-hexose by WekG, WekE, WekF, and WekD: Enzymes in the Wek pathway responsible for O-antigen Assembly in Escherichia coli O119

Considering the importance of bacterial glycoconjugates on virulence and host mimicry, there is a need to better understand the biosynthetic pathways of these unusual sugars to identify critical targets involved in bacterial pathogenesis. In this report, we describe the cloning, overexpression, purification, and biochemical characterization of the four central enzymes in the biosynthesis pathway for UDP-2-acetamido-4-formamido-2,4,6-trideoxy-hexose, WekG, WekE, WekF, and WekD. Product peaks from enzyme-substrate reactions were detected by using a combination of capillary electrophoresis (CE) and electrospray ionization-mass spectrometry (ESI-MS). Putative enzyme assignments were provided by protein sequence analysis. Combined with the mass spectrometric characterization of pathway intermediates, we propose a biosynthetic pathway for UDP-2-acetamido-4-formamido-2,4,6-trideoxy-hexose. This process involves C-4, C-6 dehydration, C-4 amination, and formylation. CID-ESI-MSn result confirmed that the final product is a 4 formamido derivative too rather than the 3 formamido derivatives as reported earlier.

Structure-function relationships in NDP-sugar active SDR enzymes: Fingerprints for functional annotation and enzyme engineering

Short-chain Dehydrogenase/Reductase enzymes that are active on nucleotide sugars (abbreviated as NS-SDR) are of paramount importance in the biosynthesis of rare sugars and glycosides. Some family members have already been extensively characterized due to their direct implication in metabolic disorders or in the biosynthesis of virulence factors. In this review, we combine the knowledge gathered from studies that typically focused only on one NS-SDR activity with an in-depth analysis and overview of all of the different NS-SDR families (169,076 enzyme sequences). Through this structure-based multiple sequence alignment of NS-SDRs retrieved from public databases, we could identify clear patterns in conservation and correlation of crucial residues. Supported by this analysis, we suggest updating and extending the UDP-galactose 4-epimerase "hexagonal box model" to an "heptagonal box model" for all NS-SDR enzymes. This specificity model consists of seven conserved regions surrounding the NDP-sugar substrate that serve as fingerprint for each specificity. The specificity fingerprints highlighted in this review will be beneficial for functional annotation of the large group of NS-SDR enzymes and form a guide for future enzyme engineering efforts focused on the biosynthesis of rare and specialty carbohydrates.

Structural and Biosynthetic Diversity of Nonulosonic Acids (NulOs) That Decorate Surface Structures in Bacteria

Nonulosonic acids (NulOs) are a diverse family of 9-carbon α-keto acid sugars that are involved in a wide range of functions across all branches of life. The family of NulOs includes the sialic acids as well as the prokaryote-specific NulOs. Select bacteria biosynthesize the sialic acid N-acetylneuraminic acid (Neu5Ac), and the ability to produce this sugar and its subsequent incorporation into cell-surface structures is implicated in a variety of bacteria-host interactions. Furthermore, scavenging of sialic acid from the environment for energy has been characterized across a diverse group of bacteria, mainly human commensals and pathogens. In addition to sialic acid, bacteria have the ability to biosynthesize prokaryote-specific NulOs, of which there are several known isomers characterized. These prokaryotic NulOs are similar in structure to Neu5Ac but little is known regarding their role in bacterial physiology. Here, we discuss the diversity in structure, the biosynthesis pathways, and the functions of bacteria-specific NulOs. These carbohydrates are phylogenetically widespread among bacteria, with numerous structurally unique modifications recognized. Despite the diversity in structure, the NulOs are involved in similar functions such as motility, biofilm formation, host colonization, and immune evasion.

The sps Genes Encode an Original Legionaminic Acid Pathway Required for Crust Assembly in Bacillus subtilis

The crust is the outermost spore layer of most Bacillus strains devoid of an exosporium. This outermost layer, composed of both proteins and carbohydrates, plays a major role in the adhesion and spreading of spores into the environment. Recent studies have identified several crust proteins and have provided insights about their organization at the spore surface. However, although carbohydrates are known to participate in adhesion, little is known about their composition, structure, and localization. In this study, we showed that the spore surface of Bacillus subtilis is covered with legionaminic acid (Leg), a nine-carbon backbone nonulosonic acid known to decorate the flagellin of the human pathogens Helicobacter pylori and Campylobacter jejuni We demonstrated that the spsC, spsD, spsE, spsG, and spsM genes of Bacillus subtilis are required for Leg biosynthesis during sporulation, while the spsF gene is required for Leg transfer from the mother cell to the surface of the forespore. We also characterized the activity of SpsM and highlighted an original Leg biosynthesis pathway in B. subtilis Finally, we demonstrated that Leg is required for the assembly of the crust around the spores, and we showed that in the absence of Leg, spores were more adherent to stainless steel probably because of their reduced hydrophilicity and charge.IMPORTANCE Bacillus species are a major economic and food safety concern of the food industry because of their food spoilage-causing capability and persistence. Their persistence is mainly due to their ability to form highly resistant spores adhering to the surfaces of industrial equipment. Spores of the Bacillus subtilis group are surrounded by the crust, a superficial layer which plays a key role in their adhesion properties. However, knowledge of the composition and structure of this layer remains incomplete. Here, for the first time, we identified a nonulosonic acid (Leg) at the surfaces of bacterial spores (B. subtilis). We uncovered a novel Leg biosynthesis pathway, and we demonstrated that Leg is required for proper crust assembly. This work contributes to the description of the structure and composition of Bacillus spores which has been under way for decades, and it provides keys to understanding the importance of carbohydrates in Bacillus adhesion and persistence in the food industry.

Synthetic Approaches for Accessing Pseudaminic Acid (Pse) Bacterial Glycans

Pseudaminic acids (Pses) are a group of non-mammalian nonulosonic acids (nulOs) that have been shown to be an important virulence factor for a number of pathogenic bacteria, including emerging multidrug-resistant ESKAPE pathogens. Despite their discovery over 30 years ago, relatively little is known about the biological significance of Pse glycans compared with their sialic acid analogues, primarily due to a lack of access to the synthetically challenging Pse architecture. Recently, however, the Pse backbone has been subjected to increasing synthetic exploration by carbohydrate (bio)chemists, and the total synthesis of complex Pse glycans achieved with inspiration from the biosynthesis and subsequent detailed study of chemical glycosylation by using Pse donors. Herein, context is provided for these efforts by summarising recent synthetic approaches pioneered for accessing Pse glycans, which are set to open up this underexplored area of glycoscience to the wider scientific community.

Mechanistic and structural studies into the biosynthesis of the bacterial sugar pseudaminic acid (Pse5Ac7Ac)

The non-mammalian nonulosonic acid sugar pseudaminic acid (Pse) is present on the surface of a number of human pathogens including Campylobacter jejuni and Helicobacter pylori and other bacteria such as multidrug resistant Acinetobacter baumannii. It is likely important for evasion of the host immune sysyem, and also plays a role in bacterial motility through flagellin glycosylation. Herein we review the mechanistic and structural characterisation of the enzymes responsible for the biosynthesis of the Pse parent structure, Pse5Ac7Ac in bacteria.

Structural Insight into a Novel Formyltransferase and Evolution to a Nonribosomal Peptide Synthetase Tailoring Domain

Nonribosomal peptide synthetases (NRPSs) increase the chemical diversity of their products by acquiring tailoring domains. Linear gramicidin synthetase starts with a tailoring formylation (F) domain, which likely originated from a sugar formyltransferase (FT) gene. Here, we present studies on an Anoxybacillus kamchatkensis sugar FT representative of the prehorizontal gene transfer FT. Gene cluster analysis reveals that this FT acts on a UDP-sugar in a novel pathway for synthesis of a 7-formamido derivative of CMP-pseudaminic acid. We recapitulate the pathway up to and including the formylation step in vitro, experimentally demonstrating the role of the FT. We also present X-ray crystal structures of the FT alone and with ligands, which unveil contrasts with other structurally characterized sugar FTs and show close structural similarity with the F domain. The structures reveal insights into the adaptations that were needed to co-opt and evolve a sugar FT into a functional and useful NRPS domain.

In vitro characterization of N-terminal truncated EpsC from Bacillus subtilis 168, a UDP-N-acetylglucosamine 4,6-dehydratase

Bacillus subtilis 168 EpsC is annotated as "Probable polysaccharide biosynthesis protein" in the SwissProt database. epsC is part of the eps operon, thought to be involved in the biosynthesis of exopolymeric substances (EPS). The present study was undertaken to determine the molecular function of EpsC. Sequence analysis of EpsC suggested the presence of a transmembrane domain. Two N-terminal deletion mutants in which residues 1-89 (EpsC₈₉) and 1-115 (EpsC₁₁₅) are deleted were cloned and overexpressed. Enzyme activity and substrate preferences were investigated by reverse phase HPLC, surface plasmon resonance (SPR) spectroscopy and absorption spectroscopy. These data show that EpsC has UDP-GlcNAc 4,6-dehydratase activity in vitro. Purified recombinant proteins were found to utilise UDP-Glc and TDP-Glc also as substrates. In addition, EpsC₁₁₅ could utilise UDP-Gal and UDP-GalNAc as substrates whereas EpsC₈₉ could only bind these two sugar nucleotides. These results show that deletion of a longer N-terminal region broadens substrate specificity. These broadened specificity is perhaps an outcome of the deletion of the putative transmembrane domain and may not be present in vivo. EpsC, together with the aminotransferase EpsN (Kaundinya CR et al., Glycobiology, 2018) and acetyltransferase EpsM (unpublished data), appears to be involved in the biosynthesis of N,N'-diacetylbacillosamine.

Molecular architectures of Pen and Pal: Key enzymes required for CMP-pseudaminic acid biosynthesis in Bacillus thuringiensis

Bacillus thuringiensis is a soil-dwelling Gram positive bacterium that has been utilized as a biopesticide for well over 60 years. It is known to contain flagella that are important for motility. One of the proteins found in flagella is flagellin, which is post-translationally modified by O-glycosylation with derivatives of pseudaminic acid. The biosynthetic pathway for the production of CMP-pseudaminic acid in B. thuringiensis, starting with UDP-N-acetyl-d-glucosamine (UDP-GlcNAc), requires seven enzymes. Here, we report the three-dimensional structures of Pen and Pal, which catalyze the first and second steps, respectively. Pen contains a tightly bound NADP(H) cofactor whereas Pal is isolated with bound NAD(H). For the X-ray analysis of Pen, the site-directed D128N/K129A mutant variant was prepared in order to trap its substrate, UDP-GlcNAc, into the active site. Pen adopts a hexameric quaternary structure with each subunit showing the bilobal architecture observed for members of the short-chain dehydrogenase/reductase superfamily. The hexameric quaternary structure is atypical for most members of the superfamily. The structure of Pal was determined in the presence of UDP. Pal adopts the more typical dimeric quaternary structure. Taken together, Pen and Pal catalyze the conversion of UDP-GlcNAc to UDP-4-keto-6-deoxy-l-N-acetylaltrosamine. Strikingly, in Gram negative bacteria such as Campylobacter jejuni and Helicobacter pylori, only a single enzyme (FlaA1) is required for the production of UDP-4-keto-6-deoxy-l-N-acetylaltrosamine. A comparison of Pen and Pal with FlaA1 reveals differences that may explain why FlaA1 is a bifunctional enzyme whereas Pen and Pal catalyze the individual steps leading to the formation of the UDP-sugar product. This investigation represents the first structural analysis of the enzymes in B. thuringiensis that are required for CMP-pseudaminic acid formation.

Rhamnose synthase activity is required for pathogenicity of the vascular wilt fungus Verticillium dahliae

The initial interaction of a pathogenic fungus with its host is complex and involves numerous metabolic pathways and regulatory proteins. Considerable attention has been devoted to proteins that play a crucial role in these interactions, with an emphasis on so-called effector molecules that are secreted by the invading microbe to establish the symbiosis. However, the contribution of other types of molecules, such as glycans, is less well appreciated. Here, we present a random genetic screen that enabled us to identify 58 novel candidate genes that are involved in the pathogenic potential of the fungal pathogen Verticillium dahliae, which causes vascular wilt diseases in over 200 dicotyledonous plant species, including economically important crops. One of the candidate genes that was identified concerns a putative biosynthetic gene involved in nucleotide sugar precursor formation, as it encodes a putative nucleotide-rhamnose synthase/epimerase-reductase (NRS/ER). This enzyme has homology to bacterial enzymes involved in the biosynthesis of the nucleotide sugar deoxy-thymidine diphosphate (dTDP)-rhamnose, a precursor of L-rhamnose, which has been shown to be required for virulence in several human pathogenic bacteria. Rhamnose is known to be a minor cell wall glycan in fungi and has therefore not been suspected as a crucial molecule in fungal-host interactions. Nevertheless, our study shows that deletion of the VdNRS/ER gene from the V. dahliae genome results in complete loss of pathogenicity on tomato and Nicotiana benthamiana plants, whereas vegetative growth and sporulation are not affected. We demonstrate that VdNRS/ER is a functional enzyme in the biosynthesis of uridine diphosphate (UDP)-rhamnose, and further analysis has revealed that VdNRS/ER deletion strains are impaired in the colonization of tomato roots. Collectively, our results demonstrate that rhamnose, although only a minor cell wall component, is essential for the pathogenicity of V. dahliae.

A four-gene operon in Bacillus cereus produces two rare spore-decorating sugars

Bacterial glycan structures on cell surfaces are critical for cell-cell recognition and adhesion and in host-pathogen interactions. Accordingly, unraveling the sugar composition of bacterial cell surfaces can shed light on bacterial growth and pathogenesis. Here, we found that two rare sugars with a 3-C-methyl-6-deoxyhexose structure were linked to spore glycans in Bacillus cereus ATCC 14579 and ATCC 10876. Moreover, we identified a four-gene operon in B. cereus ATCC 14579 that encodes proteins with the following sequential enzyme activities as determined by mass spectrometry and one- and two-dimensional NMR methods: CTP:glucose-1-phosphate cytidylyltransferase, CDP-Glc 4,6-dehydratase, NADH-dependent SAM:C-methyltransferase, and NADPH-dependent CDP-3-C-methyl-6-deoxyhexose 4-reductase. The last enzyme predominantly yielded CDP-3-C-methyl-6-deoxygulose (CDP-cereose) and likely generated a 4-epimer CDP-3-C-methyl-6-deoxyallose (CDP-cillose). Some members of the B. cereus sensu lato group produce CDP-3-C-methyl-6-deoxy sugars for the formation of cereose-containing glycans on spores, whereas others such as Bacillus anthracis do not. Gene knockouts of the Bacillus C-methyltransferase and the 4-reductase confirmed their involvement in the formation of cereose-containing glycan on B. cereus spores. We also found that cereose represented 0.2-1% spore dry weight. Moreover, mutants lacking cereose germinated faster than the wild type, yet the mutants exhibited no changes in sporulation or spore resistance to heat. The findings reported here may provide new insights into the roles of the uncommon 3-C-methyl-6-deoxy sugars in cell-surface recognition and host-pathogen interactions of the genus Bacillus.

The structure of the LPS O-chain of Fusobacterium nucleatum strain 25586 containing two novel monosaccharides, 2-acetamido-2,6-dideoxy-l-altrose and a 5-acetimidoylamino-3,5,9-trideoxy-gluco-non-2-ulosonic acid

Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about the virulence factors of this organism, and thus we have initiated studies to examine the bacterium's surface glycochemistry. We isolated lipopolysaccharide (LPS) from F. nucleatum strain 25586 and purified and performed structural analysis on the O-antigen polysaccharide. The polysaccharide contained two novel sugars, 2-acetamido-2,6-dideoxy-l-altrose (l-6dAltNAc) and a 5-acetimidoylamino-3,5,9-trideoxy-gluco-non-2-ulosonic acid (Non5Am), which was tentatively assigned the l-glycero-l-gluco configuration. The polysaccharide was found to have a trisaccharide repeating unit, which is phosphorylated with phosphocholine (PCho), and the following structure was established: -[-4-β-Nonp5Am-4-α-l-6dAltpNAc3PCho-3-β-d-QuipNAc-]- We propose the trivial name 'fusaminic acid' for the novel nonulosonic acid. It is the first occurrence of a 9-deoxynonulosonic acid with a hydroxyl group at C-7, which is occupied by an amino group in all monosaccharides of this class described so far.

Comparative genomic analysis of the flagellin glycosylation island of the Gram-positive thermophile Geobacillus

BACKGROUND

Protein glycosylation involves the post-translational attachment of sugar chains to target proteins and has been observed in all three domains of life. Post-translational glycosylation of flagellin, the main structural protein of the flagellum, is a common characteristic among many Gram-negative bacteria and Archaea. Several distinct functions have been ascribed to flagellin glycosylation, including stabilisation and maintenance of the flagellar filament, motility, surface recognition, adhesion, and virulence. However, little is known about this trait among Gram-positive bacteria.

RESULTS

Using comparative genomic approaches the flagellin glycosylation loci of multiple strains of the Gram-positive thermophilic genus Geobacillus were identified and characterized. Eighteen of thirty-six compared strains of the genus carry these loci, which show evidence of horizontal acquisition. The Geobacillus flagellin glycosylation islands (FGIs) can be clustered into five distinct types, which are predicted to encode highly variable glycans decorated with distinct and heavily modified sugars.

CONCLUSIONS

Our comparative genomic analyses showed that, while not universal, flagellin glycosylation islands are relatively common among members of the genus Geobacillus and that the encoded flagellin glycans are highly variable. This suggests that flagellin glycosylation plays an important role in the lifestyles of members of this thermophilic genus.

Biosynthesis of three N-acetylaminosugar-conjugated flavonoids using engineered Escherichia coli

Background

Nucleotide sugars serve as sugar donors for the synthesis of various glycones. The biological and chemical properties of glycones can be altered depending which sugar is attached. Bacteria synthesize unusual nucleotide sugars. A novel nucleotide sugar can be synthesized in Escherichia coli by introducing nucleotide biosynthetic genes from other microorganisms into E. coli. The engineered E. coli strains can be used as a platform for the synthesis of novel glycones.

Results

Four genes, Pdeg (UDP-N-acetylglucosamine C4,6-dehydratase), Preq (UDP-4-reductase), UDP-GlcNAc 6-DH (UDP-N-acetylglucosamine 6-dehydrogenase), and UXNAcS (UDP-N-acetylxylosamine synthase), were employed to synthesize UDP-quinovosamine, UDP-N-acetylglucosaminuronic acid, and UDP-N-acetylxylosamine in E. coli. We engineered an E. coli nucleotide sugar biosynthetic pathway to increase the pool of substrate for the target nucleotide sugars. Uridine diphosphate dependent glycosyltransferase (UGT) was also selected and introduced into E. coli. Using engineered E. coli, high levels of three novel flavonoid glycosides were obtained; 158.3 mg/L quercetin 3-O-(N-acetyl)quinovosamine, 172.5 mg/L luteolin 7-O-(N-acetyl)glucosaminuronic acid, and 160.8 mg/L quercetin 3-O-(N-acetyl)xylosamine.

Conclusions

We reconstructed an E. coli nucleotide pathway for the synthesis of UDP-quinovosamine, UDP-N-acetylglucosaminuronic acid and UDP-N-acetylxylosamine in an E. coli galU (UDP-glucose 1-phosphate uridylyltransferase) or pgm (phosphoglucomutase) deletion mutant. Using engineered E. coli strains harboring a specific UGT, three novel flavonoids glycones were synthesized. The E. coli strains used in this study can be used for the synthesis of diverse glycones.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-016-0582-8) contains supplementary material, which is available to authorized users.

The Biosynthesis of UDP-D-QuiNAc in Bacillus cereus ATCC 14579

N-acetylquinovosamine (2-acetamido-2,6-di-deoxy-d-glucose, QuiNAc) is a relatively rare amino sugar residue found in glycans of few pathogenic gram-negative bacteria where it can play a role in infection. However, little is known about QuiNAc-related polysaccharides in gram-positive bacteria. In a routine screen for bacillus glycan grown at defined medium, it was surprising to identify a QuiNAc residue in polysaccharides isolated from this gram-positive bacterium. To gain insight into the biosynthesis of these glycans, we report the identification of an operon in Bacillus cereus ATCC 14579 that contains two genes encoding activities not previously described in gram-positive bacteria. One gene encodes a UDP-N-acetylglucosamine C4,6-dehydratase, (abbreviated Pdeg) that converts UDP-GlcNAc to UDP-4-keto-4,6-d-deoxy-GlcNAc (UDP-2-acetamido-2,6-dideoxy-α-d-xylo-4-hexulose); and the second encodes a UDP-4-reductase (abbr. Preq) that converts UDP-4-keto-4,6-d-deoxy-GlcNAc to UDP-N-acetyl-quinovosamine in the presence of NADPH. Biochemical studies established that the sequential Pdeg and Preq reaction product is UDP-d-QuiNAc as determined by mass spectrometry and one- and two-dimensional NMR experiments. Also, unambiguous evidence for the conversions of the dehydratase product, UDP-α-d-4-keto-4,6-deoxy-GlcNAc, to UDP-α-d-QuiNAc was obtained using real-time ¹H-NMR spectroscopy and mass spectrometry. The two genes overlap by 4 nucleotides and similar operon organization and identical gene sequences were also identified in a few other Bacillus species suggesting they may have similar roles in the lifecycle of this class of bacteria important to human health. Our results provide new information about the ability of Bacilli to form UDP-QuiNAc and will provide insight to evaluate their role in the biology of Bacillus.