Mechanistic concepts of iron-sulfur protein biogenesis in Biology.

Iron-sulfur (Fe/S) proteins are present in virtually all living organisms and are involved in numerous cellular processes such as respiration, photosynthesis, metabolic reactions, nitrogen fixation, radical biochemistry, protein synthesis, antiviral defense, and genome maintenance. Their versatile functions may go back to the proposed role of their Fe/S cofactors in the origin of life as efficient catalysts and electron carriers. More than two decades ago, it was discovered that the in vivo synthesis of cellular Fe/S clusters and their integration into polypeptide chains requires assistance by complex proteinaceous machineries, despite the fact that Fe/S proteins can be assembled chemically in vitro.

The structure of the box C/D enzyme reveals regulation of RNA methylation.

Post-transcriptional modifications are essential to the cell life cycle, as they affect both pre-ribosomal RNA processing and ribosome assembly. The box C/D ribonucleoprotein enzyme that methylates ribosomal RNA at the 2'-O-ribose uses a multitude of guide RNAs as templates for the recognition of rRNA target sites. Two methylation guide sequences are combined on each guide RNA, the significance of which has remained unclear.