Messenger RNA and polyribosomes in Bacillus megaterium

Schaechter, Moselio; Previc, Edward; Gillespie, Marc

doi:10.1016/s0022-2836(65)80286-8

Cited by 40 publications

(18 citation statements)

References 22 publications

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“…Acetate-minimal .... 0.29 0.30 0.28 0.34 0.37 0.36 Glycerol-minimal .... 0.51 0.41 ----Glucose-minimal .... 0.66 0.47 0.58 0.45 0.71 0.47 Glycerol-complete ... 0.98 0.58 ----Glucose-complete .... 1.18 0.68 1.09 0.71 0.88 0.58 1 1~~0 .99 10.65 a pluS thymidine, uridine, and arginine in minimal media for 15TAU. Except for the results from B. megaterium (21) and possibly those from the potassiumtransport mutant E. coli B207 (5), the conflict between my results and those of others (5, 7, 25) cannot be ascribed to strain differences. The failure to measure a base line in spectro-photometric polyribosome measurements (7, 25) may account for it.…”

Section: Discussioncontrasting

confidence: 85%

“…A third gradient, without sample, was pumped through the flow cell to establish the base line. From these data, the fraction of ribosomes in polyribosomes was estimated according to Schaechter et al (21). Each recording, with the measured base line superimposed, was traced, and the tracings were cut out as indicated below and weighed.…”

Section: J Bacrerolmentioning

confidence: 99%

“…In Escherichia coli, the fraction of ribosomes in polyribosomes has been reported to increase with increasing specific growth rate (8) and with the increase in specific growth rate accompanying a nutritional shift-up (9). However, others have reported no such variations, finding the fractions of ribosomes in polyribosomes constant over a range of specific growth rate in E. coli (5,7,25) and Bacillus megaterium (21).…”

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Fraction of Ribosomes Synthesizing Protein as a Function of Specific Growth Rate

Harvey

1973

J Bacteriol

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The fraction of ribosomes engaged in protein synthesis in Escherichia coli growing at specific growth rates ranging from 0.3 to 1.2 h −1 was estimated from measurements of nascent protein/ribosome and of polyribosomes. Both measurements showed that the fraction of ribosomes synthesizing protein increased with specific growth rate, from 30 to 70% over the range studied. Polyribosome measurements made at different specific growth rates in four E. coli strains showed no significant differences between strains. The increase in the fraction of polyribosomes had begun within 30 s after a shift-up from glucose-minimal medium, and was complete within 2 to 5 min. These results indicate that the function of ribosomes is regulated.

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Section: Discussioncontrasting

confidence: 85%

Section: J Bacrerolmentioning

confidence: 99%

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confidence: 99%

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Fraction of Ribosomes Synthesizing Protein as a Function of Specific Growth Rate

Harvey

1973

J Bacteriol

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“…Electron microscopic visualization has confirmed the coupling of these processes, showing protein synthesis occurring on polyribosomes attached to messenger RNA (mRNA) transcripts which are still in association with the template DNA (3). Biochemical studies have shown that prokaryotic mRNA is labile, with an average half-life of less than 3 min (4)(5)(6)(7)(8). More stable species of mRNAs have been described, e.g., for certain T7 phage proteins (9), for penicillinase production (10) and sporulation (11) in Bacillus cereus.…”

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confidence: 96%

Very stable prokaryotic messenger RNA in chromosomeless Escherichia coli minicells.

Levy¹

1975

Proc. Natl. Acad. Sci. U.S.A.

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E. coli minicells lack DNA, yet they make protein, the synthesis of which is sensitive to chloramphenicol but insensitive to rifamycin. This protein is coded for by very stable cellular mRNA with an estimated half-life of 40-80 min. In an R factor-containing minicell, two very different species of mRNA are observed: (i) R factor-specific mRNA with a short half-life whose synthesis is rifamycinsensitive and (if) cellular mRNA with a long half-life whose synthesis is rifamycin-insensitive. These In prokaryotic cells, gene transcription and subsequent translation to protein appear to occur coordinately (1, 2). Electron microscopic visualization has confirmed the coupling of these processes, showing protein synthesis occurring on polyribosomes attached to messenger RNA (mRNA) transcripts which are still in association with the template DNA (3). Biochemical studies have shown that prokaryotic mRNA is labile, with an average half-life of less than 3 min (4-8).More stable species of mRNAs have been described, e.g., for certain T7 phage proteins (9), for penicillinase production (10) and sporulation (11) in Bacillus cereus. Recently a group of outer membrane proteins in Escherichia coli has been identified which appear synthesized from mRNA species with half-lives of 5.5-11.5 min (12,13 (18). Sodium dodecyl sulfate (NaDodSO4)/polyacrylamide gel electrophoresis was performed in 10% gels for analysis of proteins (19) and in 5% gels for analysis of RNA (20).E. coli lipoprotein was determined by chromatography on Whatman 3 paper in a solvent system consisting of isobutyric acid/i M ammonium hydroxide (5:3) (21). Samples of radioactively labeled cells and minicells were boiled for 15 min to release the soluble material. After several washes in distilled water, the samples were spotted onto paper and chromatographed for 15 hr.This initial chromatography was used to remove free lipoprotein (22) Osborn, personal communication). After centrifugation at 46,000 rpm in a SW 50.1 rotor (Beckman) for 12 hr, the fractions were collected and radioactivity was determined on trichloroacetic acid-treated paper discs (25). Extraction of membranes with sodium lauryl sarcosinate (Sarkosyl) was as described (19,26).

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“…Their lysis mixture was modified to contain 0.06 M KCI (final concentration). The fraction of ribosomes in polyribosomes was estimated as described by Schaechter et al (22), with the useof a Beckman model E analytical ultracentrifuge equipped with schlieren optics. To 0.5 ml of lysate, 0.05 ml of TM buffer containing 10 ug of pancreatic ribonuclease per ml was added.…”

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Regulation of Ribosomal Protein Synthesis in Escherichia coli

Harvey

1970

J Bacteriol

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The kinetics of synthesis of ribosomal, nonribosomal, and total protein, and of ribosomal ribonucleic acid (RNA), were measured in Escherichia coli during a shiftup involving a doubling of specific growth rate. The increase in ribosomal protein synthesis was not accompanied by a corresponding decrease in non-ribosomal protein synthesis. Thus, the average rate of protein synthesis per ribosome increased after the shift. The increase did not occur by an increase in polypeptide chain growth rates. The average growth periods of ribosomal and nonribosomal proteins did not change after a shift, and were constant in cells in balanced growth over a wide range of specific growth rates. The average growth period for ribosomal protein was twice that for nonribosomal protein. The fraction of ribosomes in polyribosomes was found to increa3e after the shift, accounting for the increase in ribosomal protein synthesis and in protein synthesis per ribosome. These results show that ribosomal protein synthesis is regulated by control of initiation of either transcription or translation of ribosomal protein messenger RNA, by some means other than availability of free ribosomes. If the messenger for ribosomal protein is ribosomal RNA, the conclusions can be extended to apply to regulation of ribosomal RNA synthesis. In support of this, it is shown that ribosomal RNA and ribosomal protein synthesis are closely coordinated during a shift.

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Messenger RNA and polyribosomes in Bacillus megaterium

Cited by 40 publications

References 22 publications

Fraction of Ribosomes Synthesizing Protein as a Function of Specific Growth Rate

Fraction of Ribosomes Synthesizing Protein as a Function of Specific Growth Rate

Very stable prokaryotic messenger RNA in chromosomeless Escherichia coli minicells.

Regulation of Ribosomal Protein Synthesis in Escherichia coli

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