[86] Intermedites in the biosynthesis of tryptophan

Smith, Oliver H.; Yanofsky, Charles

doi:10.1016/0076-6879(63)06226-1

Cited by 36 publications

(17 citation statements)

References 6 publications

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“…It was prepared by the method of Gibson (13). CDRP was prepared by the method of Smith and Yanofsky (21). Indole-glycerol-phosphate was prepared by the method of Wegman and Crawford (22).…”

Section: Methodsmentioning

confidence: 99%

Enzymes of Tryptophan Biosynthesis in Serratia marcescens

Hutchinson

Belser

1969

J Bacteriol

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In Serratia marcescens, the tryptophan biosynthetic enzymes were formed coordinately. A number of tryptophan auxotrophs showed single biochemical lesions; several mutants showed pleiotropic effects. Sucrose density gradient centrifugation revealed an unique pattern of migration of the tryptophan biosynthetic enzymes. The repression response of the Serratia enzymes to exogenous tryptophan was fivefold more sensitive than that found in Escherichia coli. When this information is contrasted with the available information on the other Enterobacteriaceae, one is compelled to conclude that S. marcescens enjoys a rather marked evolutionary divergence from the other enteric organisms.

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“…It was prepared by the method of Gibson (13). CDRP was prepared by the method of Smith and Yanofsky (21). Indole-glycerol-phosphate was prepared by the method of Wegman and Crawford (22).…”

Section: Methodsmentioning

confidence: 99%

Enzymes of Tryptophan Biosynthesis in Serratia marcescens

Hutchinson

Belser

1969

J Bacteriol

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“…Independently arising Su+ colonies were picked and transferred to grids on minimal proline plates and allowed to grow [16][17][18] The fact that su8 and not su7 suppressed the T4 ochre mutation indicates that the former is an ochre suppressor, while the 1htter may be an amber suppressor.…”

mentioning

confidence: 99%

RECESSIVE LETHALS: A NEW CLASS OF NONSENSE SUPPRESSORS IN Escherichia coli

Soll

Berg

1969

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

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Abstract.-Two new nonsense suppressors in Escherichia coli were found in partial diploids carrying F'14 and were shown to be on the episome. These suppressors can exist only in cells which also contain the su-allele, i.e., su+/suheterozygotes. Presumably the mutations cause an alteration of an essential cellular component, the complete loss of which is lethal. Su7, an amber suppressor, has an efficiency of 76 per cent and su8, an ochre suppressor, an efficiency of 4 per cent.Extensive searches by several workers have revealed only three amber suppressors in Escherichia coli.'-3 Such suppressors are thought to result from changes in the anticodon of a transfer RNA (tRNA) allowing the altered tRNA to pair with UAG, the amber triplet, at the ribosome.4-6 Seven amino acids have codons related to UAG by a single base change: therefore, it should be possible to generate at least one suppressor for each of these amino acids by a mutation affecting the anticodon. The fact that no suppressors have been found which insert some of these amino acids (tryptophan, lysine, and glutamic acid) suggests a fundamental restriction on the generation of suppressors.7 Assuming that anticodon changes in certain tRNA's do not prevent aminoacylation, the most likely restriction is that the tRNA which might become the suppressor is indispensable, and its loss is lethal to the cell. If this were true, such potentially lethal mutations affecting tRNA's should be recoverable in cells which are diploid for these genes. Such strains can retain one copy of a duplicated indispensable tRNA gene to perform its normal function, allowing the second to mutate to yield a suppressor. Other potential mutations leading to suppression but not involving tRNA's might also be lethal to the haploid cell but could be revealed in partial diploids. This report presents a general approach for the isolation of such recessive lethal suppressors and describes a new amber and a new ochre suppressor of this type.Materials and Methods.

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“…It has been shown in Pseudomonas putida that strains with mutations in the trpA gene accumulate indole glycerol donor phage phosphate when grown in the presence of limiting tryptophan and excrete indole glycerol into the culture medium (23). Mutations in trpB can also result in the excretion of indole glycerol, since a block in trpB results in the accumulation of indole glycerol phosphate.…”

Section: Resultsmentioning

confidence: 99%

Genetic and physical analyses of Caulobacter crescentus trp genes

Winkler¹,

Schoenlein²,

Ross³

et al. 1984

J Bacteriol

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Caulobacter crescentus trp mutants were identified from a collection of auxotrophs. Precursor feeding experiments, accumulation studies, and complementation experiments resulted in the identification of six genes corresponding to trpA, trpB, trpC, trpD, trpE, and trpF. Genetic mapping experiments demonstrated that the trp genes were in two clusters, trpCDE and trpFBA, and a 5.4-kilobase restriction fragment from the C. crescentus chromosome was isolated that contained the trpFBA gene cluster. Complementation experiments with clones containing the 5.4-kilobase fragment indicated that trpF was expressed in Escherichia coli and that all three genes were expressed in Pseudomonas putida. This expression was lost in both organisms when the pBR322 tet gene promoter was inactivated, indicating that all three genes were transcribed in the same orientation from the tet promoter. Thus, the C. crescentus promoters do not seem to be expressed in E. coli or P. putida. Complementation of the C. crescentus trp mutants indicated that the tet promoter was not necessary for expression in C. crescentus and suggested that at least two native promoters were present for expression of the trpF, trpB, and trpA genes. Taken together, these results indicate that C. crescentus promoters may have structures that are significantly different from the promoters of other gram-negative species.* Corresponding author. 279that the trp genes are located in two widely separated regions of the C. crescentus chromosome. In addition, we have isolated a 5.4-kilobase (kb) fragment of C. crescentus DNA, and we demonstrate that it contains the trpFBA gene cluster.

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[86] Intermedites in the biosynthesis of tryptophan

Cited by 36 publications

References 6 publications

Enzymes of Tryptophan Biosynthesis in Serratia marcescens

Enzymes of Tryptophan Biosynthesis in Serratia marcescens

RECESSIVE LETHALS: A NEW CLASS OF NONSENSE SUPPRESSORS IN Escherichia coli

Genetic and physical analyses of Caulobacter crescentus trp genes

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