Interactions between Mutations Affecting Ribosome Synthesis in Escherichia coli

Butler, Peter D.; Cattaneo, Emilio; Wild, D. G.

doi:10.1099/00221287-131-4-945

Cited by 1 publication

(2 citation statements)

References 13 publications

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“…First, the phenotypes produced are very similar in the stringent strain CP78 and the relaxed strain JM107 (and in a third strain, HVT45.2 [3], to which the rpmBG mutations have also been transferred). Second, an at least superficially similar accumulation of ribosome precursors occurs in strain TP28; this accumulation persists when the mutation is transferred to other strains (1,3). Third, the rpmBG mutations in strains AM81 and AM90 act to suppress the antibiotic dependence of strain AM and thus clearly interact with mutations carried by the latter.…”

Section: Discussionmentioning

confidence: 99%

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Mutations in the rpmBG operon of Escherichia coli that affect ribosome assembly

Maguire

Wild

1997

J Bacteriol

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The rpmBG operon of Escherichia coli codes for ribosomal proteins L28 and L33. Two strains with mutations in the operon are AM81, whose ribosomes lack protein L28, and AM90, whose ribosomes are without protein L33. Neither strain showed major defects in ribosome assembly. However, when the mutations were transferred to other strains of E. coli, ribosome synthesis was greatly perturbed and precursor ribonucleoproteins accumulated. In the new backgrounds, the mutation in rpmB was complemented by synthesis of protein L28 from a plasmid; the rpmG mutation was not complemented by protein L33 because synthesis of protein L28 from the upstream rpmB gene was also greatly reduced. The results suggest that protein L33, in contrast to protein L28, has at best a minor role in ribosome assembly and function.The work reported herein was done to resolve a paradox noted during a study (6) on ribosome assembly by strains of Escherichia coli with mutations in the rpmBG operon. This operon codes for two proteins, L28 and L33, from the larger (50S) ribosomal subunit. Reconstitution in vitro has provided a map showing the interdependence of ribosomal proteins in the assembly of this subunit. A general feature of the map is that in nearly all cases, including that of proteins L28 and L33, the L proteins specified by an operon interact with each other (11). A recent model shows these two proteins as near-neighbors in the 50S subunit (23). These factors suggest that proteins L28 and L33 may have related roles in ribosome synthesis and that strains of E. coli with mutations in the rpmBG operon should be defective in ribosome assembly.One such strain is TP28, which makes proteins L28 and L33 at about half their normal rates (2) due to a single base change (G to A) in the rpmB Shine-Dalgarno sequence in the leader region of the mRNA (6). As a consequence, strain TP28 oversynthesizes RNA and accumulates an abnormal precursor to 50S ribosomal subunits. These precursor (47S) particles lack L28 and L33 and contain substoichiometric amounts of three or four other proteins. The 70S ribosomes of strain TP28 have a full complement of ribosomal proteins, including L28 and L33, but about half the peptidyltransferase activity of that of the 70S ribosomes from their parent strain and so synthesize proteins poorly (21). Abnormal assembly may generate ribosomes that are conformationally altered.Other strains with defects in the rpmBG operon originated differently. Dabbs (7) isolated an erythromycin-dependent mutant, strain AM, and showed that the dependency was readily suppressed by spontaneous mutations that resulted in failure to make one protein (or sometimes two) from a set of about 15 ribosomal proteins. Among the erythromycin-independent revertants with proteins missing from ribosomes were strain AM81, without protein L28, strain AM90, without protein L33, and strain AM108, without either protein. Total cell proteins from strains AM90 and AM108 did not cross-react with antibodies raised against the missing proteins; strain AM81 was not tested (9)...

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Section: Discussionmentioning

confidence: 99%

“…These defects include mutations conferring erythromycin dependence and resistance. When the rpmBG mutation in strain TP28 was transferred to other strains, the latter acquired a phenotype similar to that of strain TP28 (1,3). Here, we describe experiments that put the defective rpmBG operons from strains AM81 and AM90 in other genetic backgrounds.…”

mentioning

confidence: 97%

Mutations in the rpmBG operon of Escherichia coli that affect ribosome assembly

Maguire

Wild

1997

J Bacteriol

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show abstract

Interactions between Mutations Affecting Ribosome Synthesis in Escherichia coli

Cited by 1 publication

References 13 publications

Mutations in the rpmBG operon of Escherichia coli that affect ribosome assembly

Mutations in the rpmBG operon of Escherichia coli that affect ribosome assembly

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