Dataset Information

Choosing the right metal: case studies of class I ribonucleotide reductases.

ABSTRACT: Over one-third of all proteins require metallation for function (Waldron, K. J., Rutherford, J. C., Ford, D., and Robinson, N.J. (2009) Nature 460, 823-830). As biochemical studies of most proteins depend on their isolation subsequent to recombinant expression (i.e. they are seldom purified from their host organism), there is no gold standard to assess faithful metallocofactor assembly and associated function. The biosynthetic machinery for metallocofactor formation in the recombinant expression system may be absent, inadequately expressed, or incompatible with a heterologously expressed protein. A combination of biochemical and genetic studies has led to the identification of key proteins involved in biosynthesis and likely repair of the metallocofactor of ribonucleotide reductases in both bacteria and the budding yeast. In this minireview, we will discuss the recent progress in understanding controlled delivery of metal, oxidants, and reducing equivalents for cofactor assembly in ribonucleotide reductases and highlight issues associated with controlling Fe/Mn metallation and avoidance of mismetallation.

SUBMITTER: Huang M

PROVIDER: S-EPMC4192465 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Choosing the right metal: case studies of class I ribonucleotide reductases.

Huang Mingxia M Parker Mackenzie J MJ Stubbe JoAnne J

The Journal of biological chemistry 20140826 41

Over one-third of all proteins require metallation for function (Waldron, K. J., Rutherford, J. C., Ford, D., and Robinson, N.J. (2009) Nature 460, 823-830). As biochemical studies of most proteins depend on their isolation subsequent to recombinant expression (i.e. they are seldom purified from their host organism), there is no gold standard to assess faithful metallocofactor assembly and associated function. The biosynthetic machinery for metallocofactor formation in the recombinant expression ...[more]

PMID: 25160629

Similar Datasets

Project description:How cells ensure correct metallation of a given protein and whether a degree of promiscuity in metal binding has evolved are largely unanswered questions. In a classic case, iron- and manganese-dependent superoxide dismutases (SODs) catalyze the disproportionation of superoxide using highly similar protein scaffolds and nearly identical active sites. However, most of these enzymes are active with only one metal, although both metals can bind in vitro and in vivo. Iron(ii) and manganese(ii) bind weakly to most proteins and possess similar coordination preferences. Their distinct redox properties suggest that they are unlikely to be interchangeable in biological systems except when they function in Lewis acid catalytic roles, yet recent work suggests this is not always the case. This review summarizes the diversity of ways in which iron and manganese are substituted in similar or identical protein frameworks. As models, we discuss (1) enzymes, such as epimerases, thought to use Fe(II) as a Lewis acid under normal growth conditions but which switch to Mn(II) under oxidative stress; (2) extradiol dioxygenases, which have been found to use both Fe(II) and Mn(II), the redox role of which in catalysis remains to be elucidated; (3) SODs, which use redox chemistry and are generally metal-specific; and (4) the class I ribonucleotide reductases (RNRs), which have evolved unique biosynthetic pathways to control metallation. The primary focus is the class Ib RNRs, which can catalyze formation of a stable radical on a tyrosine residue in their ?2 subunits using either a di-iron or a recently characterized dimanganese cofactor. The physiological roles of enzymes that can switch between iron and manganese cofactors are discussed, as are insights obtained from the studies of many groups regarding iron and manganese homeostasis and the divergent and convergent strategies organisms use for control of protein metallation. We propose that, in many of the systems discussed, "discrimination" between metals is not performed by the protein itself, but it is instead determined by the environment in which the protein is expressed.

Project description:Chronic lung infections by the ubiquitous and extremely adaptable opportunistic pathogen Pseudomonas aeruginosa correlate with the formation of a biofilm, where bacteria grow in association with an extracellular matrix and display a wide range of changes in gene expression and metabolism. This leads to increased resistance to physical stress and antibiotic therapies, while enhancing cell-to-cell communication. Oxygen diffusion through the complex biofilm structure generates an oxygen concentration gradient, leading to the appearance of anaerobic microenvironments. Ribonucleotide reductases (RNRs) are a family of highly sophisticated enzymes responsible for the synthesis of the deoxyribonucleotides, and they constitute the only de novo pathway for the formation of the building blocks needed for DNA synthesis and repair. P. aeruginosa is one of the few bacteria encoding all three known RNR classes (Ia, II, and III). Class Ia RNRs are oxygen dependent, class II are oxygen independent, and class III are oxygen sensitive. A tight control of RNR activity is essential for anaerobic growth and therefore for biofilm development. In this work we explored the role of the different RNR classes in biofilm formation under aerobic and anaerobic initial conditions and using static and continuous-flow biofilm models. We demonstrated the importance of class II and III RNR for proper cell division in biofilm development and maturation. We also determined that these classes are transcriptionally induced during biofilm formation and under anaerobic conditions. The molecular mechanism of their anaerobic regulation was also studied, finding that the Anr/Dnr system is responsible for class II RNR induction. These data can be integrated with previous knowledge about biofilms in a model where these structures are understood as a set of layers determined by oxygen concentration and contain cells with different RNR expression profiles, bringing us a step closer to the understanding of this complex growth pattern, essential for P. aeruginosa chronic infections.

Dataset Information

Choosing the right metal: case studies of class I ribonucleotide reductases.

Publications

Choosing the right metal: case studies of class I ribonucleotide reductases.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets