Cobalt and Corrinoid Transport and Biochemistry

Abstract

In this chapter, we focus on the biochemistry of non-corrin cobalt and on a subset of corrinoid-containing enzymes. We review the import of cobalt in prokaryotes and discuss two members of the non-corrin cobalt-dependent enzymes, nitrile hydratase and methionine aminopeptidase. Cobalt is best known for its central role in alkylcorrinoid cofactors, where the unique properties of the cobalt-carbon bond are exploited to catalyze chemically challenging biotransformations. We discuss the import of corrinoids and the reactions catalyzed by the acyl-CoA mutases, the -fastest-growing subfamily of adenosylcobalamin (AdoCbl)-dependent enzymes. AdoCbl is used as a radical reservoir to catalyze 1,2 rearrangement reactions. The loading of AdoCbl-dependent enzymes with the correct cofactor form is critically important for their functions and is gated by chaperones that use the chemical energy of GTP hydrolysis to ensure the fidelity of the process. Recent insights into the organization and editing functions of G-protein chaperones in the context of AdoCbl-dependent enzymes that they support, are discussed.

Structural Basis for Substrate Specificity in Adenosylcobalamin-dependent Isobutyryl-CoA Mutase and Related Acyl-CoA Mutases

“…First, archaeal MCMs cluster with ICMs rather than with bacterial and eukaryotic MCMs (Fig. 9) as noted previously (5,11,59). Archaeal MCMs encode the substrate-binding and Cbl-binding domains on separate polypeptides, in notable contrast to most bacterial (see below) and all eukaryotic MCMs, which encode both domains on a single polypeptide.…”

Geological and Chemical Factors that Impacted the Biological Utilization of Cobalt in the Archean Eon

“…Methionine can be synthesized by cobalamin-dependent methionine synthase (MetH) or cobalamin-independent methionine synthase (MetE) (Evans et al, 2004;Ludwig & Matthews, 1997;Peariso et al, 2001;Pejcha & Ludwig, 2005). Microorganisms are the only natural sources of Cbl and its derivatives; land plants, fungi, and various microbes possess the Cbl-independent MetE pathway (Brown, 2005;Cracan & Banerjee, 2013;Giovannoni et al, 2005;Helliwell et al, 2011;Kräutler, 2005).…”

“…Except for land plants and fungi, cobalt is a unique biological cofactor due to its importance as the metal center of the corrin ring in vitamin B 12 (also referred to as cobalamin (Cbl); Cracan & Banerjee, ; Helliwell et al, ; Kräutler, ; Okamoto & Eltis, ). Co changes oxidation state within cobalamin allowing for unique carbon radical chemistry to be exploited (Kräutler, ).…”

Receptor uptake arrays for vitamin B12, siderophores, and glycans shape bacterial communities

“…Siderophores and corrinoids share certain aspects of uptake, diversity, and competitive consequences. The receptor and transport systems for siderophores and corrinoids derive from the same family of ABC transporters (Cracan & Banerjee, ). The close homology often makes it difficult to distinguish siderophore from corrinoid transporters by amino acid sequence (Yi et al., ).…”