Insight into the Role of Escherichia coli MobB in Molybdenum Cofactor Biosynthesis Based on the High Resolution Crystal Structure

McLuskey, Karen; Harrison, J.A.; Schüttelkopf, Alexander W.; Boxer, David H.; Hunter, William N.

doi:10.1074/jbc.m301485200

Cited by 25 publications

(25 citation statements)

References 47 publications

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“…In vivo, however, MobB, a GTP-binding protein interacting with MobA (20,49), may assist the GTP binding step. A docking model of MobA and MobB has suggested that GTP is bound to a shared binding site at the interface between both proteins (20). However, MobB did not enhance the activity of MGD formation under our assay conditions (data not shown).…”

Section: Sample Bvsmentioning

confidence: 99%

“…In E. coli, GMP attachment to Mo-MPT is catalyzed by the MobA and MobB proteins, thereby forming MGD (19). MobA is crucial for this reaction and acts as a GTP:molybdopterin guanylyltransferase (14), whereas MobB is not essential (20). The type of Moco and ligand composition at the molybdenum atom divides the molybdoenzymes of E. coli into three families with the following coordination environment: the sulfite oxidase family (dioxo Mo-MPT with a protein cysteinate ligand), the xanthine oxidase family (mono-oxo MCD with a terminal sulfur ligand), and the dimethyl sulfoxide (DMSO) reductase family (bis-MGD with one oxo and one amino acid ligand) (1,3).…”

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confidence: 99%

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Identification of a Bis-molybdopterin Intermediate in Molybdenum Cofactor Biosynthesis in Escherichia coli

Reschke

Sigfridsson²,

Kaufmann

et al. 2013

Journal of Biological Chemistry

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Section: Sample Bvsmentioning

confidence: 99%

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confidence: 99%

Identification of a Bis-molybdopterin Intermediate in Molybdenum Cofactor Biosynthesis in Escherichia coli

Reschke

Sigfridsson²,

Kaufmann

et al. 2013

Journal of Biological Chemistry

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“…S3). MobB functions downstream of MoaE in bacteria to form molybdopterin guanine dinucleotide common to enzymes of the DMSO reductase family (24,25). The MoaE homolog of H. volcanii and other archaea is likely to be linked to Ubl protein function, based on its amino acid sequence relationship to the large subunit of MPT synthase and its association with SAMP1 as detected by MS (20).…”

mentioning

confidence: 99%

E1- and ubiquitin-like proteins provide a direct link between protein conjugation and sulfur transfer in archaea

Miranda

Nembhard

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

180

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Based on our recent work with Haloferax volcanii, ubiquitin-like (Ubl) proteins (SAMP1 and SAMP2) are known to be covalently attached to proteins in archaea. Here, we investigated the enzymes required for the formation of these Ubl-protein conjugates (SAMPylation) and whether this system is linked to sulfur transfer. Markerless in-frame deletions were generated in H. volcanii target genes. The mutants were examined for: (i) the formation of Ubl protein conjugates, (ii) growth under various conditions, including those requiring the synthesis of the sulfur-containing molybdenum cofactor (MoCo), and (iii) the thiolation of tRNA. With this approach we found that UbaA of the E1/MoeB/ThiF superfamily was required for the formation of both SAMP1-and SAMP2-protein conjugates. In addition, UbaA, SAMP1, and MoaE (a homolog of the large subunit of molybdopterin synthase) were essential for MoCo-dependent dimethyl sulfoxide reductase activity, suggesting that these proteins function in MoCo-biosynthesis. UbaA and SAMP2 were also crucial for optimal growth at high temperature and the thiolation of tRNA. Based on these results, we propose a working model for archaea in which the E1-like UbaA can activate multiple Ubl SAMPs for protein conjugation as well as for sulfur transfer. In sulfur transfer, SAMP1 and SAMP2 appear specific for MoCo biosynthesis and the thiolation of tRNA, respectively. Overall, this study provides a fundamental insight into the diverse cellular functions of the Ubl system. posttranslational modification | tRNA modification | proteasomes

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“…Whereas MobA was shown to be essential for this reaction (18), the role of MobB still remains uncertain. From the crystal structure, it was postulated that MobB is an adapter protein that acts in concert with MobA to achieve the efficient biosynthesis and utilization of MGD (19).…”

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Transfer of the Molybdenum Cofactor Synthesized by Rhodobacter capsulatus MoeA to XdhC and MobA

Neumann

Stöcklein

Leimkühler

2007

Journal of Biological Chemistry

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The molybdenum cofactor (Moco) 2 is an essential component of a diverse group of enzymes involved in important redox reactions in the global carbon, nitrogen, and sulfur cycles. Moco consists of a molybdenum atom coordinated to the dithiolene group of a tricyclic pyranopterin referred to as molybdopterin (MPT) (1). The biosynthesis of Moco is highly conserved in eukaryotes and prokaryotes (1) and can be divided into three general steps. In the first step, GTP is converted to the meta-stable intermediate Precursor Z (2, 3). In the second step, Precursor Z is further transformed by MPT synthase into MPT by generation of its characteristic dithiolene group (4, 5). In the third step, molybdate is inserted to the MPT dithiolene sulfurs, a reaction catalyzed by MogA and MoeA in Escherichia coli (6 -8). MoeA mediates molybdenum ligation, whereas MogA helps to facilitate this step in an ATP-dependent manner (8). Recently, studies with the homologous Arabidopsis thaliana CNX1 protein G and E domains identified the formation of an MPT-AMP intermediate before the ligation of molybdate to the MPT moiety (9, 10). An unexpected observation in the crystal structure of the A. thaliana CNX1 protein G domain was the identification of copper bound to the MPT-AMP dithiolene sulfurs (11). Up to now, the function of this novel MPT ligand has been unknown, but it was speculated that copper might play a role in sulfur transfer to Precursor Z, in protection of the MPT dithiolene from oxidation, and/or in presentation of a suitable leaving group for molybdenum insertion (12). To date, copper-MPT-AMP has not been identified as an intermediate in the biosynthesis of Moco in E. coli (8).After the insertion of molybdenum into MPT in E. coli, Moco either can be directly inserted into molybdoenzymes (such as YedY) binding the MPT form of Moco (13) or is further modified by attachment of GMP (14, 15), forming the bis-MPT guanine dinucleotide (bis-MGD) form of Moco found in enzymes of the Me 2 SO reductase family (16). In E. coli, the GMP attachment to Moco is catalyzed by the MobA and MobB proteins (17). Whereas MobA was shown to be essential for this reaction (18), the role of MobB still remains uncertain. From the crystal structure, it was postulated that MobB is an adapter protein that acts in concert with MobA to achieve the efficient biosynthesis and utilization of MGD (19).Enzymes containing the MPT form of Moco belong to either the sulfite oxidase or xanthine oxidase family, whereas enzymes binding the bis-MGD form of Moco belong to the Me 2 SO reductase family of molybdoenzymes. In Rhodobacter capsulatus, xanthine dehydrogenase (XDH; EC 1.17.1.4) is the only identified enzyme harboring the MPT form of the cofactor, whereas all other known molybdoenzymes bind the bis-MGD form of the cofactor (20). An essential role for the XdhC protein in the maturation of R. capsulatus XDH has been described, which entails binding of Moco and its insertion into the XdhB subunit of XDH (21). For all members of the xanthine oxidase family, the sulfurate...

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Insight into the Role of Escherichia coli MobB in Molybdenum Cofactor Biosynthesis Based on the High Resolution Crystal Structure

Cited by 25 publications

References 47 publications

Identification of a Bis-molybdopterin Intermediate in Molybdenum Cofactor Biosynthesis in Escherichia coli

Identification of a Bis-molybdopterin Intermediate in Molybdenum Cofactor Biosynthesis in Escherichia coli

E1- and ubiquitin-like proteins provide a direct link between protein conjugation and sulfur transfer in archaea

Transfer of the Molybdenum Cofactor Synthesized by Rhodobacter capsulatus MoeA to XdhC and MobA

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