NAC controls cotranslational N-terminal methionine excision in eukaryotes.

N-terminal methionine excision from newly synthesized proteins, catalyzed cotranslationally by methionine aminopeptidases (METAPs), is an essential and universally conserved process that plays a key role in cell homeostasis and protein biogenesis. However, how METAPs interact with ribosomes and how their cleavage specificity is ensured is unknown. We discovered that in eukaryotes the nascent polypeptide-associated complex (NAC) controls ribosome binding of METAP1.

Fluorescence-based monitoring of ribosome assembly landscapes.

Background: Ribosomes and functional complexes of them have been analyzed at the atomic level. Far less is known about the dynamic assembly and degradation events that define the half-life of ribosomes and guarantee their quality control.

Results: We developed a system that allows visualization of intact ribosomal subunits and assembly intermediates (i.

Validation of a fluorescence-based screening concept to identify ribosome assembly defects in Escherichia coli.

While the structure of mature ribosomes is analyzed in atomic detail considerably less is known about their assembly process in living cells. This is mainly due to technical and conceptual hurdles. To analyze ribosome assembly in vivo, we designed and engineered an Escherichiacoli strain--using chromosomal gene knock-in techniques--that harbors large and small ribosomal subunits labeled with the fluorescent proteins EGFP and mCherry, respectively.