Ribosomes are the organelles responsible for translation of mRNAs into proteins and are therefore
essential for every living cell. In the last decade, methodological advancements triggered a vast boost in
our understanding how ribosomes are assembled from freshly transcribed ribosomal RNA and ribosomal
proteins. However, very little is known about the very first steps of this assembly process. This holds
especially true for the eukaryotic ribosome.
We recently obtained three consecutive cryo-EM maps of near atomic resolution that depict the earliest
known phase of the assembly of the small ribosomal subunit. These structures for the first time visualize
the initial phase of rRNA domain compaction and ribosomal protein incorporation. In addition, we could
determine the association order of ribosomal proteins using stable isotope labeling.
This FWF project aims to dissect the determinants for the incorporation of the very first ribosomal
proteins and to identify which role selected assembly factors play during this process. This will be
achieved by determining binding characteristics of ribosomal proteins and assembly factors to the SSU-
processome and naked rRNA in a quantitative manner. This will provide us with a deep mechanistic
understanding of the initial phase of ribosome assembly.