Assembly of ribosomal subunits affected in a ribosomal mutant of E. coli having an altered L22 protein

Pardo, Daniel; Vola, Christine; Rosset, Roland

doi:10.1007/bf00433305

Cited by 9 publications

(6 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Under these conditions, mature ribosomal subunits migrate at the 50S position. Precursor 50S subunits, however, can migrate differently, either due to the loss of loosely bound r-proteins and ribosome-associated proteins or due to a change in their conformation (5,27,57). As expected, the polysome profiles from cgtA E ϩ cell extracts showed predominantly 30S and 50S subunits.…”

Section: Resultssupporting

confidence: 68%

TheEscherichia coliGTPase CgtA_EIs Involved in Late Steps of Large Ribosome Assembly

et al. 2006

View full text Add to dashboard Cite

The bacterial ribosome is an extremely complicated macromolecular complex the in vivo biogenesis of which is poorly understood. Although several bona fide assembly factors have been identified, their precise functions and temporal relationships are not clearly defined. Here we describe the involvement of an Escherichia coli GTPase, CgtA E , in late steps of large ribosomal subunit biogenesis. CgtA E belongs to the Obg/CgtA GTPase subfamily, whose highly conserved members are predominantly involved in ribosome function. Mutations in CgtA E cause both polysome and rRNA processing defects; small-and large-subunit precursor rRNAs accumulate in a cgtA E mutant. In this study we apply a new semiquantitative proteomic approach to show that CgtA E is required for optimal incorporation of certain late-assembly ribosomal proteins into the large ribosomal subunit. Moreover, we demonstrate the interaction with the 50S ribosomal subunits of specific nonribosomal proteins (including heretofore uncharacterized proteins) and define possible temporal relationships between these proteins and CgtA E . We also show that purified CgtA E associates with purified ribosomal particles in the GTP-bound form. Finally, CgtA E cofractionates with the mature 50S but not with intermediate particles accumulated in other large ribosome assembly mutants.Although assembly of prokaryotic ribosomes from purified ribosomal proteins (r-proteins) and rRNAs can occur independently in vitro (51, 52, 75), accumulating evidence suggests that, as in eukaryotes, in vivo prokaryotic ribosome biogenesis depends on the aid of nonribosomal factors. The higher temperature, increased Mg 2ϩ concentration, and longer incubation times necessary for in vitro relative to in vivo conditions (51) imply that the likely role of accessory factors is to expedite ribosome maturation by reducing the activation energies for the rate-limiting reactions. Although not complicated by the involvement of different cellular compartments, the prokaryotic ribosome assembly process is far from simple, requiring coordinated synthesis of 3 rRNAs (5S, 16S, and 23S) and 55 r-proteins, processing and modification of these components, and their appropriate sequential unification to produce mature ribosomes. The details of how this process is controlled temporally, even spatially, in the small bacterial cell are incompletely understood.More than 170 nonribosomal proteins that transiently associate with different preribosomal particles have been identified in Saccharomyces cerevisiae (19,22,38,62), largely due to progress in combining biochemical affinity purification methods with newly developed proteomic techniques (24,25,29,54,58,61). By contrast, only a few such assembly factors have been found in bacteria, and most were identified via conventional genetic methods. These proteins consist of RNA-modifying enzymes such as methyltransferases and pseudouridine synthases, RNA-remodeling proteins such as RNA helicases, chaperones, GTPases, and proteins with unknown functions (1,

show abstract

Section: Resultssupporting

confidence: 68%

TheEscherichia coliGTPase CgtA_EIs Involved in Late Steps of Large Ribosome Assembly

et al. 2006

View full text Add to dashboard Cite

show abstract

“…In cases when biogenesis of one of the subunits is affected, delays in maturation of the other are often observed. Two ribosomal proteins, S5 and L22, shown to be important for the assembly of their respective subunit, when mutated, affect maturation of both the 30S and the 50S particles (149,150,165). Deletion of the gene rluD, which codes for a pseudouridine synthase that modifies the 23S rRNA, leads not only to immature 50S subunits but also to immature 30S subunits (74).…”

Section: S Quality Control and Translation Initiationmentioning

confidence: 99%

Ribosome Biogenesis and the Translation Process inEscherichia coli

Kaczanowska

Rydén-Aulin

2007

Microbiol Mol Biol Rev

356

379

View full text Add to dashboard Cite

SUMMARY Translation, the decoding of mRNA into protein, is the third and final element of the central dogma. The ribosome, a nucleoprotein particle, is responsible and essential for this process. The bacterial ribosome consists of three rRNA molecules and approximately 55 proteins, components that are put together in an intricate and tightly regulated way. When finally matured, the quality of the particle, as well as the amount of active ribosomes, must be checked. The focus of this review is ribosome biogenesis in Escherichia coli and its cross-talk with the ongoing protein synthesis. We discuss how the ribosomal components are produced and how their synthesis is regulated according to growth rate and the nutritional contents of the medium. We also present the many accessory factors important for the correct assembly process, the list of which has grown substantially during the last few years, even though the precise mechanisms and roles of most of the proteins are not understood.

show abstract

“…Pardo et al (86) noted that their erythromycin-resistant mutant of E. coli showed low temperature-sensitive assembly (Sad phenotype) when it was grown at 22ЊC. This apparent instability of ribosome assembly in the resistant mutant may be too high a price to pay to survive as a resistant mutant in vivo in the absence of antibiotic and might explain why erythromycin-resistant mutants with altered ribosomal proteins have not been found among clinical isolates.…”

Section: Resistance Mechanismsmentioning

confidence: 99%

Erythromycin resistance by ribosome modification

Weisblum

1995

Antimicrob Agents Chemother

925

752

View full text Add to dashboard Cite

Assembly of ribosomal subunits affected in a ribosomal mutant of E. coli having an altered L22 protein

Cited by 9 publications

References 14 publications

TheEscherichia coliGTPase CgtA_EIs Involved in Late Steps of Large Ribosome Assembly

TheEscherichia coliGTPase CgtA_EIs Involved in Late Steps of Large Ribosome Assembly

Ribosome Biogenesis and the Translation Process inEscherichia coli

Erythromycin resistance by ribosome modification

Contact Info

Product

Resources

About

Assembly of ribosomal subunits affected in a ribosomal mutant of E. coli having an altered L22 protein

Cited by 9 publications

References 14 publications

TheEscherichia coliGTPase CgtAEIs Involved in Late Steps of Large Ribosome Assembly

TheEscherichia coliGTPase CgtAEIs Involved in Late Steps of Large Ribosome Assembly

Ribosome Biogenesis and the Translation Process inEscherichia coli

Erythromycin resistance by ribosome modification

Contact Info

Product

Resources

About

TheEscherichia coliGTPase CgtA_EIs Involved in Late Steps of Large Ribosome Assembly

TheEscherichia coliGTPase CgtA_EIs Involved in Late Steps of Large Ribosome Assembly