Elucidation of the Dual Role of Mycobacterial MoeZR in Molybdenum Cofactor Biosynthesis and Cysteine Biosynthesis

Martin Voss,Silke Leimkühler,Manfred Nimtz

doi:10.1371/journal.pone.0028170

Martin Voss, Silke Leimkühler + Show 1 more

Open Access

https://doi.org/10.1371/journal.pone.0028170

Copy DOI

Abstract

The pathway of molybdenum cofactor biosynthesis has been studied in detail by using proteins from Mycobacterium species, which contain several homologs associated with the first steps of Moco biosynthesis. While all Mycobacteria species contain a MoeZR, only some strains have acquired an additional homolog, MoeBR, by horizontal gene transfer. The role of MoeBR and MoeZR was studied in detail for the interaction with the two MoaD-homologs involved in Moco biosynthesis, MoaD1 and MoaD2, in addition to the CysO protein involved in cysteine biosynthesis. We show that both proteins have a role in Moco biosynthesis, while only MoeZR, but not MoeBR, has an additional role in cysteine biosynthesis. MoeZR and MoeBR were able to complement an E. coli moeB mutant strain, but only in conjunction with the Mycobacterial MoaD1 or MoaD2 proteins. Both proteins were able to sulfurate MoaD1 and MoaD2 in vivo, while only MoeZR additionally transferred the sulfur to CysO. Our in vivo studies show that Mycobacteria have acquired several homologs to maintain Moco biosynthesis. MoeZR has a dual role in Moco- and cysteine biosynthesis and is involved in the sulfuration of MoaD and CysO, whereas MoeBR only has a role in Moco biosynthesis, which is not an essential function for Mycobacteria.

Highlights

Among the metabolic pathways requiring sulfur transfer are those leading to the formation of FeS clusters, biotin, thiamin, lipoic acid, molybdopterin (MPT), and sulfur-containing bases in RNA [1]
Complementation of the strains by the Mycobacterial proteins would result in the production of active nitrate reductase, a molybdenum cofactor (Moco)-containing enzyme, the activity of which is dependent on the ability of cells to synthesize Moco
A distinguishing feature of members of the M. tuberculosis species is their possession of multiple homologs associated with the first step of Moco biosynthesis [14,23]

Summary

Introduction

Among the metabolic pathways requiring sulfur transfer are those leading to the formation of FeS clusters, biotin, thiamin, lipoic acid, molybdopterin (MPT), and sulfur-containing bases in RNA [1]. A new pathway for cysteine biosynthesis involving sulfur transfer has been elucidated in Mycobacterium tuberculosis recently [2,3] This pathway involves the ubiquitin-fold protein CysO that contains a C-terminal thiocarboxylate group at the last glycine of a GG-motif as sulfide donor [4]. The CysO activating enzyme MoeZ belongs to a superfamily of proteins consisting of related proteins that are members of pathways involved in the transfer of sulfur-containing moieties to metabolites [8]. Members of this family are referred to as MoeB, MoeBR, MoeZR, MoeZ and MOCS3 [9]. E. coli MoeB was shown to activate the small subunit of MPT synthase MoaD to form an acyl-adenylate intermediate at its C-

Methods

Results

Conclusion