Native Corrinoids from<i>Clostridium cochlearium</i>Are Adeninylcobamides: Spectroscopic Analysis and Identification of Pseudovitamin B<sub>12</sub>and Factor A

Hoffmann, Bernd; Oberhuber, Michael; Stupperich, Erhard; Bothe, Harald; Buckel, Wolfgañg; Konrat, Robert; Kräutler, Bernhard

doi:10.1128/jb.182.17.4773-4782.2000

Cited by 52 publications

(63 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Although LPG3 grazes on these cyanobacterial species that robustly produce pseudocobalamin, its requirement for heterotrophic bacteria that produce cobalamin suggests that it has specificity for cobalamin and cannot utilize pseudocobalamin. While pseudocobalamin is produced by many bacterial species, including cyanobacteria (19), Lactobacillus reuteri (43), and Clostridium cochlearium (44), other eukaryotes that utilize corrinoids also have specificity for cobalamin over pseudocobalamin. The human intrinsic factor protein binds cobalamin and facilitates absorption across the small intestine and has specificity for cobalamin over pseudocobalamin (45).…”

Section: Discussionmentioning

confidence: 99%

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria

Beld

Brahamsha

2017

Appl Environ Microbiol

View full text Add to dashboard Cite

Amoebae are unicellular eukaryotes that consume microbial prey through phagocytosis, playing a role in shaping microbial food webs. Many amoebal species can be cultivated axenically in rich media or monoxenically with a single bacterial prey species. Here, we characterize heterolobosean amoeba LPG3, a recent natural isolate, which is unable to grow on unicellular cyanobacteria, its primary food source, in the absence of a heterotrophic bacterium, a Pseudomonas species coisolate. To investigate the molecular basis of this requirement for heterotrophic bacteria, we performed a screen using the defined nonredundant transposon library of Vibrio cholerae, which implicated genes in corrinoid uptake and biosynthesis. Furthermore, cobalamin synthase deletion mutations in V. cholerae and the Pseudomonas species coisolate do not support the growth of amoeba LPG3 on cyanobacteria. While cyanobacteria are robust producers of a corrinoid variant called pseudocobalamin, this variant does not support the growth of amoeba LPG3. Instead, we show that it requires cobalamin that is produced by the Pseudomonas species coisolate. The diversity of eukaryotes utilizing corrinoids is poorly understood, and this amoebal corrinoid auxotroph serves as a model for examining predator-prey interactions and micronutrient transfer in bacterivores underpinning microbial food webs.IMPORTANCE Cyanobacteria are important primary producers in aquatic environments, where they are grazed upon by a variety of phagotrophic protists and, hence, have an impact on nutrient flux at the base of microbial food webs. Here, we characterize amoebal isolate LPG3, which consumes cyanobacteria as its primary food source but also requires heterotrophic bacteria as a source of corrinoid vitamins. Amoeba LPG3 specifically requires the corrinoid variant produced by heterotrophic bacteria and cannot grow on cyanobacteria alone, as they produce a different corrinoid variant. This same corrinoid specificity is also exhibited by other eukaryotes, including humans and algae. This amoebal model system allows us to dissect predator-prey interactions to uncover factors that may shape microbial food webs while also providing insight into corrinoid specificity in eukaryotes.KEYWORDS amoeba, corrinoids, microbial interactions, vitamin B 12 U nicellular organisms dominate the eukaryotic phylogenetic tree of life. Although protists make up a significant part of natural microbial communities, they have been largely overlooked and are understudied as simple model eukaryotes (1, 2). While culture-independent metagenomic studies provide insight into the abundance and natural diversity of protists in environmental settings (3), in-depth characterization requires the isolation and cultivation of individual species. A large range of eukaryotic microalgal species have been cultivated and studied, particularly as a source of renewable biofuel compounds in recent years (4, 5); however, besides microalgae, there are only a few protist microbes developed as model systems. Amoebae are...

show abstract

Section: Discussionmentioning

confidence: 99%

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria

Beld

Brahamsha

2017

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…Therefore, they cannot use Cbi as a source of corrinoids. When provided with CN-pseudo-B 12 (16), this strain grew using ethanolamine as the sole carbon source. Pseudo-B 12 must therefore serve as an alternative to cobalamin and allow activity of ethanolamine ammonia lyase.…”

Section: Conditions That Prevent Synthesis or Installation Of Any ␣-Amentioning

confidence: 99%

“…1) include the base 5,6-dimethylbenzimidazole (DMB) as an ␣-axial ligand. Prokaryotes, the only producers of vitamin B 12 , make "complete" corrinoid cofactors with a variety of alternative ␣-axial ligands, including benzimidazoles, phenols, and purines (16,52). These alternative corrinoids may be functional equivalents of coenzyme B 12 for many bacterial enzymes, but functional differences are suggested by the selectivity of the human assimilatory protein, intrinsic factor for cobalamin, the DMB-containing vitamin B 12 (53).…”

mentioning

confidence: 99%

One Pathway Can Incorporate either Adenine or Dimethylbenzimidazole as an α-Axial Ligand of B ₁₂ Cofactors in Salmonella enterica

et al. 2008

Self Cite

View full text Add to dashboard Cite

Coenzyme B 12 (Ado-Cbl) and vitamin B 12 (CN-B 12 ) (Fig. 1) include the base 5,6-dimethylbenzimidazole (DMB) as an ␣-axial ligand. Prokaryotes, the only producers of vitamin B 12 , make "complete" corrinoid cofactors with a variety of alternative ␣-axial ligands, including benzimidazoles, phenols, and purines (16, 52). These alternative corrinoids may be functional equivalents of coenzyme B 12 for many bacterial enzymes, but functional differences are suggested by the selectivity of the human assimilatory protein, intrinsic factor for cobalamin, the DMB-containing vitamin B 12 (53).Under strictly anaerobic growth conditions, Salmonella enterica synthesizes corrinoids de novo (44) and installs either adenine (to form pseudo-coenzyme B 12 [Ado-pseudo-B 12 ]) or 2-methyl-adenine (to form adenosyl-factor A) as an ␣-axial ligand (22). If even trace amounts of oxygen are present, DMB-containing B 12 (cobalamin [Cbl]) is also made (39). When grown aerobically on glucose, S. enterica cannot synthesize the corrin moiety, which must be supplied as an "incomplete" corrinoid, such as cobinamide (Cbi), with its corrin ring and aminopropanol side chain. Under these conditions, coenzyme B 12 is made, with DMB as the ␣-axial ligand (20). Figure 2 diagrams the de novo (anaerobic) synthetic pathway and assimilation of exogenous Cbi or . Notice that the ␤-ligand adenosyl can be added (by CobA) to three different substrates and that the (CN) 2 Cbi supplied as the corrin ring source is not a normal CobA substrate.Here, the origins and installation of ␣-axial ligands are approached genetically using an unexpected feature of S. enterica. While S. enterica can use exogenous Cbi to produce B 12 cofactors (cobalamins) during aerobic growth on glucose (20), it makes only about 100 molecules per cell (2). This is apparently insufficient B 12 coenzyme to support growth on ethanolamine (5) unless the DMB base is also supplied. That is, under these conditions, cells neither make sufficient DMB nor install an alternative ligand to allow corrinoid-dependent aerobic growth on ethanolamine (5).This situation allowed positive selection of mutants that can grow on ethanolamine plus Cbi without added DMB. These mutants were expected to show either increased endogenous DMB production or to install an alternative base as an ␣-axial ligand. All of the mutants made pseudo-B 12 cofactors, which have adenine as an ␣-axial ligand, and most of these mutations affected purine metabolism so as to increase the intracellular level of free adenine base. The same set of enzymes (CobUSTC) installs either adenine base (to form pseudo-B 12 ) or DMB (to form vitamin B 12 ). A model suggests how the choice is made. MATERIALS AND METHODSBacterial strains and transposons. Strains were derived from S. enterica (serovar Typhimurium) LT2

show abstract

“…Several recent reports have shown that pseudo-B 12 is the dominant corrinoid produced by the anaerobes Clostridium cochlearium (9) and Lactobacillus reuteri (24), the cyanobacteria Nostoc commune (32) and Aphanizomenon flos-aquae (17), and the alga Aphanothece sacrum (31). Historically, these corrinoids have been viewed as "alternate" forms.…”

mentioning

confidence: 99%

Pseudo-B ₁₂ Joins the Cofactor Family

Taga

Walker

2008

J Bacteriol

View full text Add to dashboard Cite

Native Corrinoids fromClostridium cochleariumAre Adeninylcobamides: Spectroscopic Analysis and Identification of Pseudovitamin B₁₂and Factor A

Cited by 52 publications

References 67 publications

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria

One Pathway Can Incorporate either Adenine or Dimethylbenzimidazole as an α-Axial Ligand of B ₁₂ Cofactors in Salmonella enterica

Pseudo-B ₁₂ Joins the Cofactor Family

Contact Info

Product

Resources

About

Native Corrinoids fromClostridium cochleariumAre Adeninylcobamides: Spectroscopic Analysis and Identification of Pseudovitamin B12and Factor A

Cited by 52 publications

References 67 publications

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria

An Amoebal Grazer of Cyanobacteria Requires Cobalamin Produced by Heterotrophic Bacteria

One Pathway Can Incorporate either Adenine or Dimethylbenzimidazole as an α-Axial Ligand of B 12 Cofactors in Salmonella enterica

Pseudo-B 12 Joins the Cofactor Family

Contact Info

Product

Resources

About

Native Corrinoids fromClostridium cochleariumAre Adeninylcobamides: Spectroscopic Analysis and Identification of Pseudovitamin B₁₂and Factor A

One Pathway Can Incorporate either Adenine or Dimethylbenzimidazole as an α-Axial Ligand of B ₁₂ Cofactors in Salmonella enterica

Pseudo-B ₁₂ Joins the Cofactor Family