8c99
Cryo-EM captures early ribosome assembly in actionCryo-EM captures early ribosome assembly in action
Structural highlights
FunctionRL4_ECOLI One of the primary rRNA binding proteins, this protein initially binds near the 5'-end of the 23S rRNA. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome.[1] Protein L4 is a both a transcriptional repressor and a translational repressor protein; these two functions are independent of each other. It regulates transcription of the S10 operon (to which L4 belongs) by causing premature termination of transcription within the S10 leader; termination absolutely requires the NusA protein. L4 controls the translation of the S10 operon by binding to its mRNA. The regions of L4 that control regulation (residues 131-210) are different from those required for ribosome assembly (residues 89-103).[2] Forms part of the polypeptide exit tunnel.[3] Can regulate expression from Citrobacter freundii, Haemophilus influenzae, Morganella morganii, Salmonella typhimurium, Serratia marcescens, Vibrio cholerae and Yersinia enterocolitica (but not Pseudomonas aeruginosa) S10 leaders in vitro.[4] Publication Abstract from PubMedRibosome biogenesis is a fundamental multi-step cellular process in all domains of life that involves the production, processing, folding, and modification of ribosomal RNAs (rRNAs) and ribosomal proteins. To obtain insights into the still unexplored early assembly phase of the bacterial 50S subunit, we exploited a minimal in vitro reconstitution system using purified ribosomal components and scalable reaction conditions. Time-limited assembly assays combined with cryo-EM analysis visualizes the structurally complex assembly pathway starting with a particle consisting of ordered density for only ~500 nucleotides of 23S rRNA domain I and three ribosomal proteins. In addition, our structural analysis reveals that early 50S assembly occurs in a domain-wise fashion, while late 50S assembly proceeds incrementally. Furthermore, we find that both ribosomal proteins and folded rRNA helices, occupying surface exposed regions on pre-50S particles, induce, or stabilize rRNA folds within adjacent regions, thereby creating cooperativity. Cryo-EM captures early ribosome assembly in action.,Qin B, Lauer SM, Balke A, Vieira-Vieira CH, Burger J, Mielke T, Selbach M, Scheerer P, Spahn CMT, Nikolay R Nat Commun. 2023 Feb 17;14(1):898. doi: 10.1038/s41467-023-36607-9. PMID:36797249[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
|
| ||||||||||||||||