Thematic minireview series: metals in biology 2014.

This thematic series, the sixth in the Metals in Biology collection beginning in 2009, addresses the issue of why certain metals are used by particular enzymes, as well as the consequences of using the wrong metal. This prologue introduces the 2014 Metals in Biology thematic series. The first minireview in the series deals with general aspects of metal specificity, and the next two deal with specific cases, the enzyme ribonucleotide reductase and iron/manganese homeostasis in the bacterium Bacillus subtilis. The fourth discusses metal selection in oxidative stress, and the final minireview discusses lysosome-related organelles as mediators of metal homeostasis.