Mutations affecting the structural genes and the genes coding for modifying enzymes for ribosomal proteins in Escherichia coli

Isono, Setsuko; Isono, Katsumi; Hirota, Yukinori

doi:10.1007/bf00270371

Cited by 50 publications

(20 citation statements)

References 14 publications

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“…Three native ribosomal proteins in E. coli are also a-N-acetylated and are modified by 3 different enzymes (Isono et al, 1978). The enzymes responsible for N-terminal acetylations are most likely not responsible for the side-chain acetylations found in this work because separate enzymes have been shown to be responsible for these reactions in eukaryotic systems.…”

Section: 914mentioning

confidence: 73%

Isolation of Escherichia coli synthesized recombinant eukaryotic proteins that contain 6‐N‐acetyllysine

et al. 1994

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Recombinant porcine (rpST) and bovine somatotropins (rbST) synthesized in Escherichia coli contain the amino acid, e-N-acetyllysine. This amino acid was initially discovered in place of the normal lysine'44 in a modified reversed-phase HPLC (RP-HPLC) species of rpST. Mass spectrometry and amino acid sequencing of a tryptic peptide isolated from this RP-HPLC purified protein were used to identify this altered residue as e-N-acetyllysine.Ion-exchange chromatography was utilized to prepare low isoelectric point (PI) forms of rpST and rbST, which are enriched in e-N-acetyllysine. Electrospray mass spectrometry demonstrated that the majority of the protein in these low PI fractions contained species 42 Da larger than normal. Immobilized pH gradient electrophoresis (IPG) of the ion-exchange purified low PI proteins was used to isolate several monoacetylated species of rpST and rbST. The location of the acetylated lysine in each IPG-purified protein was determined by tryptic peptide mapping and amino acid sequencing of the altered tryptic peptides. Amino acid analyses of enzymatic digests of rpST and rbST were also used to confirm the presence of e-N-acetyllysine in these recombinant proteins. These data demonstrate that a significant portion of rpST and rbST produced in E. coli contain this unusual amino acid.

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Section: 914mentioning

confidence: 73%

Isolation of Escherichia coli synthesized recombinant eukaryotic proteins that contain 6‐N‐acetyllysine

et al. 1994

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“…The use of a collection of E. coli mutants of independent origin for the screening of mutations in a given gene has been reported (14)(15)(16)(17)(18). Although isolates of this collection were originally selected for their thermal sensitivity, mutations unrelated to the thermal sensitivity are common because of the severe mutagenesis used.…”

Section: Resultsmentioning

confidence: 99%

Mutations in the gene coding for Escherichia coli DNA topoisomerase I affect transcription and transposition.

Sternglanz¹,

DiNardo²,

Voelkel³

et al. 1981

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

257

156

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Mutations in top, the structural gene for Escherichia coli DNA topoisomerase I, have been identified and mapped at 28 min on the chromosome, near cysB. Strains carrying deletions of the top gene are viable. The top mutations, however, do exert pleiotropic effects on transcription and transposition. Mutants lacking DNA topoisomerase I have a more rapid rate of induction and a higher level of catabolite-sensitive enzymes including tryptophanase and -galactosidase. This general activation of transcription by top mutations can be attributed to an increase in the negative superhelicity of the DNA in vivo when the topoisomerase activity is abolished. The frequency of transposition of Tn5, a transposon carrying kanamycin resistance, is decreased by a factor of 40 or more in top mutants. A direct or indirect role of the topoisomerase in transposition is discussed. The transposition frequency ofTn3, however, is not dependent on top. Based on the studies of the E. coli top mutants, it appears that the supX gene, which was originally studied in SalmoneUa typhimurium [Dubnau, E. & Margolin, P. (1972) Mol. Gen. Genet. 117, 91-112] is likely to be the structural gene for DNA topoisomerase I.Escherichia coli DNA topoisomerase I, also known as w protein, has been the subject of extensive studies (for a review, see ref.1). The enzyme is a single polypeptide ofabout 110,000 daltons. In vitro it catalyzes the relaxation of negatively supercoiled DNA (2), the knotting and unknotting of single-stranded DNA rings (3), the linking of single-stranded DNA rings of complementary sequences into intertwined duplex rings (4), and the catenation and decatenation of duplex DNA rings when at least one member of a pair of participating duplex rings has a singlechain scission (5). The catalysis of these topological isomerization reactions by the enzyme is believed to involve transient single-stranded breakage of DNA phosphodiester bonds (1).In contrast to the extensive in vitro studies, there has been little work on the functions of the enzyme in vivo. We have therefore undertaken the isolation and characterization of mutants deficient in DNA topoisomerase I activity. In this communication, we report the identification of a number of mutations in the structural gene for the enzyme and the genetic mapping ofthis gene, which we have termed top, on the E. coli chromosome. Roles of the enzyme in the regulation of transcription ofa number ofoperons and in the transposition of several transposons are also implicated based on our initial characterization of the mutants.MATERIALS AND METHODS Bacterial Strains. All strains used were E. coli K-12 derivatives. The strain used to produce the collection oftemperaturesensitive mutants was PA3092 F-thr leu thi argH thyA his trp lacYl mtl xyl malA mel tonA str supE. Two mutants from this collection were found to have top mutations, JE10010 topl0 and JE10250 top250 (6). Other strains used include: P4X8 Hfr met; KV385 met lacYl xyl mtl str topl0; PLK831 F-trpE pyrF gal-25 nirA strA195; JTT1, a trp+ top+...

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“…Among the mutants we have characterized for r-protein alterations, there were two mutants with altered S18 protein (10). One of them, JE1677 (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…More recently, we have isolated another mutant that contained an alteration in protein L9 (10). Because the gene for this protein (rplI) had not yet been mapped, we performed mapping of this mutation.…”

mentioning

confidence: 99%

Cluster of ribosomal protein genes in Escherichia coli containing genes for proteins S6, S18, and L9.

Isono¹,

Kitakawa²

1978

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

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A mutant of Escbenchia coli K-12 isolated for temperature-sensitive growth was found to harbor an alteration in ribosomal protein L9. Because the chromosomal location of the structural gene for this protein (rpll) was not known, we mapped the mutation by using various Hfr strains. The fine mapping of this gene by Plkc phage-mediated transductions has revealed that it forms a gene cluster at 94 min on the E coli genetic map together with the genes coding for two other ribo-

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Mutations affecting the structural genes and the genes coding for modifying enzymes for ribosomal proteins in Escherichia coli

Cited by 50 publications

References 14 publications

Isolation of Escherichia coli synthesized recombinant eukaryotic proteins that contain 6‐N‐acetyllysine

Isolation of Escherichia coli synthesized recombinant eukaryotic proteins that contain 6‐N‐acetyllysine

Mutations in the gene coding for Escherichia coli DNA topoisomerase I affect transcription and transposition.

Cluster of ribosomal protein genes in Escherichia coli containing genes for proteins S6, S18, and L9.

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