Visualizing molecular juggling within a B12-dependent methyltransferase complex

Kung, Yan; Ando, Nozomi; Doukov, Tzanko; Blasiak, Leah C.; Bender, Güneş; Seravalli, Javier; Ragsdale, Stephen W.; Drennan, Catherine L.

doi:10.1038/nature10916

Cited by 67 publications

(131 citation statements)

References 40 publications

Supporting

Mentioning

123

Contrasting

Order By: Relevance

“…Furthermore, electron transfer between D60-CoFeSP and RACo could not be initiated by the addition of ATP. Recently, a role of the [4Fe4S] cluster domain in complex formation was also described for the MeTr:CoFeSP complex structure of Moorella thermoacetica 15 . Although the structure and function of RACo and MeTr are completely different, CoFeSP interacts with both proteins using the same mobile domains to stabilize two different complexes ( Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

ATP-induced electron transfer by redox-selective partner recognition

et al. 2014

View full text Add to dashboard Cite

Thermodynamically unfavourable electron transfers are enabled by coupling to an energysupplying reaction. How the energy is transduced from the exergonic to the endergonic process is largely unknown. Here we provide the structural basis for an energy transduction process in the reductive activation of B 12 -dependent methyltransferases. The transfer of one electron from an activating enzyme to the cobalamin cofactor is energetically uphill and relies on coupling to an ATPase reaction. Our results demonstrate that the key to coupling is, besides the oxidation state-dependent complex formation, the conformational gating of the electron transfer. Complex formation induces a substitution of the ligand at the electronaccepting Co ion. Addition of ATP initiates electron transfer by provoking conformational changes that destabilize the complex. We show how remodelling of the electron-accepting Co 2 þ promotes ATP-dependent electron transfer; an efficient strategy not seen in other electron-transferring ATPases.

show abstract

Section: Resultsmentioning

confidence: 99%

ATP-induced electron transfer by redox-selective partner recognition

et al. 2014

View full text Add to dashboard Cite

show abstract

“…DNA synthesis in D. mccartyi is predicted to be dependent on the class II RNR NrdJ, an enzyme that functions with the cobamide bound in the base-on form (31). In contrast, RDases and CFeSPs, the two other types of corrinoiddependent enzymes present in D. mccartyi, have been shown in other organisms to function with the corrinoid cofactor bound in the "base-off" position (30,44,51). The requirement of D. mccartyi for benzimidazolyl cobamides differs from that of Sulfurospirillum multivorans, which uses the purinyl cobamide noradeninylcobamide as a cofactor for its PCE RDase, and is capable of reductive dechlorination of PCE only to dichloroethene (28).…”

Section: Discussionmentioning

confidence: 99%

Versatility in Corrinoid Salvaging and Remodeling Pathways Supports Corrinoid-Dependent Metabolism in Dehalococcoides mccartyi

Seth

Men

et al. 2012

Appl Environ Microbiol

112

164

View full text Add to dashboard Cite

dCorrinoids are cobalt-containing molecules that function as enzyme cofactors in a wide variety of organisms but are produced solely by a subset of prokaryotes. Specific corrinoids are identified by the structure of their axial ligands. The lower axial ligand of a corrinoid can be a benzimidazole, purine, or phenolic compound. Though it is known that many organisms obtain corrinoids from the environment, the variety of corrinoids that can serve as cofactors for any one organism is largely unstudied. Here, we examine the range of corrinoids that function as cofactors for corrinoid-dependent metabolism in Dehalococcoides mccartyi strain 195. Dehalococcoides bacteria play an important role in the bioremediation of chlorinated solvents in the environment because of their unique ability to convert the common groundwater contaminants perchloroethene and trichloroethene to the innocuous end product ethene. All isolated D. mccartyi strains require exogenous corrinoids such as vitamin B 12 for growth. However, like many other corrinoid-dependent bacteria, none of the well-characterized D. mccartyi strains has been shown to be capable of synthesizing corrinoids de novo. In this study, we investigate the ability of D. mccartyi strain 195 to use specific corrinoids, as well as its ability to modify imported corrinoids to a functional form. We show that strain 195 can use only specific corrinoids containing benzimidazole lower ligands but is capable of remodeling other corrinoids by lower ligand replacement when provided a functional benzimidazole base. This study of corrinoid utilization and modification by D. mccartyi provides insight into the array of strategies that microorganisms employ in acquiring essential nutrients from the environment.

show abstract

“…The C-terminal domain of CfsA also contains an alpha helix, the so called "cap helix," that interacts with the lower face of the cofactor (17). CfsB, having no ortholog in ND132, folds as a (␤␣) 8 barrel and interacts with the upper axial face (the face that receives and donates the methyl group) of the corrinoid (24). The interaction of the CfsA and CfsB subunits of CFeSP on either side of the corrinoid has been proposed to stabilize the Co(I) state of the cofactor (17).…”

mentioning

confidence: 99%

Site-Directed Mutagenesis of HgcA and HgcB Reveals Amino Acid Residues Important for Mercury Methylation

Smith

Bridou

Johs

et al. 2015

Appl Environ Microbiol

View full text Add to dashboard Cite

f Methylmercury is a potent neurotoxin that is produced by anaerobic microorganisms from inorganic mercury by a recently discovered pathway. A two-gene cluster, consisting of hgcA and hgcB, encodes two of the proteins essential for this activity. hgcA encodes a corrinoid protein with a strictly conserved cysteine proposed to be the ligand for cobalt in the corrinoid cofactor, whereas hgcB encodes a ferredoxin-like protein thought to be an electron donor to HgcA. Deletion of either gene eliminates mercury methylation by the methylator Desulfovibrio desulfuricans ND132. Here, site-directed mutants of HgcA and HgcB were constructed to determine amino acid residues essential for mercury methylation. Mutations of the strictly conserved residue Cys93 in HgcA, the proposed ligand for the corrinoid cobalt, to Ala or Thr completely abolished the methylation capacity, but a His substitution produced measurable methylmercury. Mutations of conserved amino acids near Cys93 had various impacts on the methylation capacity but showed that the structure of the putative "cap helix" region harboring Cys93 is crucial for methylation function. In the ferredoxin-like protein HgcB, only one of two conserved cysteines found at the C terminus was necessary for methylation, but either cysteine sufficed. An additional, strictly conserved cysteine, Cys73, was also determined to be essential for methylation. This study supports the previously predicted importance of Cys93 in HgcA for methylation of mercury and reveals additional residues in HgcA and HgcB that facilitate the production of this neurotoxin. M ethylmercury (MeHg), a neurotoxin present in the environment, is a significant risk to human health in many regions of the world (1). Sources of the mercury (Hg) substrate from which MeHg is derived are numerous and include both natural and anthropogenic sources (2, 3). Currently, only anaerobic microbes are known to produce MeHg (4), predominantly in sediments of aquatic environments. Once MeHg is produced, it accumulates in the aquatic food chain, becoming concentrated in top predators (5). Human exposure to MeHg results from eating those predators, for example, in marine food webs, shark, swordfish, albacore tuna, and eel. Once in the body, MeHg passes through the intestinal epithelium, usually complexed with thiol groups in proteins (6). Eventually, MeHg buildup in humans can lead to neuropathies in adults and developmental disorders in children exposed in utero (2).Anaerobic Deltaproteobacteria are thought to be the major contributors of MeHg found in the environment (7, 8), although potentially significant contributions by methanogens and fermenting bacteria have recently been discovered (9-11). In 2013, we showed that the proteins encoded by two genes in two bacteria of the Deltaproteobacteria phylum, Desulfovibrio desulfuricans ND132 and Geobacter sulfurreducens PCA, are essential for the conversion of Hg(II) to MeHg (12). That study was stimulated by the work of Choi and colleagues (13-15) implicating a 40-kDa corrinoid protein i...

show abstract

Visualizing molecular juggling within a B12-dependent methyltransferase complex

Cited by 67 publications

References 40 publications

ATP-induced electron transfer by redox-selective partner recognition

ATP-induced electron transfer by redox-selective partner recognition

Versatility in Corrinoid Salvaging and Remodeling Pathways Supports Corrinoid-Dependent Metabolism in Dehalococcoides mccartyi

Site-Directed Mutagenesis of HgcA and HgcB Reveals Amino Acid Residues Important for Mercury Methylation

Contact Info

Product

Resources

About