The Formation of a New Enzymatically Active Protein as a Result of Suppression

Crawford, Irving P.; Yanofsky, Charles

doi:10.1073/pnas.45.8.1280

Cited by 29 publications

(12 citation statements)

References 9 publications

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“…As reported previously (Crawford and Yanofsky, 1959;Brody and Yanofsky, 1963), allelespecific suppressor mutations reverse the effects of only certain mutations in the tryptophan synthetase A gene. Although many different mechanisms of suppression may exist, it has been shown that suppressors of the A mutants lead to an alteration in the primary structure of the A protein (Brody and Yanofsky, 1963).…”

supporting

confidence: 73%

Mechanism Studies of Suppressor-Gene Action

Brody¹,

Yanofsky²

1965

J Bacteriol

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Mechanism studies of suppressor-gene action. J. Bacteriol. 90:687-695. 1965.-Mutations which change the primary structure of the A protein of the tryptophan synthetase of Escherichia coli can be reversed by allele-specific suppressor mutations. Normally, the suppressors of a particular A mutant lead to the appearance of small amounts of a wild-type-like A protein (su-A protein), in addition to the cross-reacting material antigenically similar to the normal A protein (CRM-A protein). In some cases, the particular ratio of su-A protein to CRM-A protein, indicative of a given suppressor gene, was increased when that suppressor gene was transduced into a different strain, such as a K-12 Hfr stock of E. coli. In these cases, there was a general correlation between an increased ratio and a marked instability of the suppressor gene. However, stable suppressed stocks were isolated in the Hfr strain, which also produced a high proportion of su-A protein. The ratios of su-A protein to CRM-A protein remained relatively constant under conditions of tryptophan repression in three different suppressor stocks, suggesting that the formation of each of the su-A proteins does not involve the interaction of a CRM-A protein with any other cellular constituent. It would appear, then, that the changes in the primary structure of the A protein which lead to the formation of the su-A proteins are determined before or during, but not after, the synthesis of the polypeptide chain. The specificity of amino acid activation was investigated in strains bearing one of the suppressor genes. These studies failed to reveal any significant alteration in the amino acyl ribonucleic acid (RNA) synthetases or the transfer RNA molecules for arginine, glycine, histidine, and tyrosine.

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supporting

confidence: 73%

Mechanism Studies of Suppressor-Gene Action

Brody¹,

Yanofsky²

1965

J Bacteriol

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“…lThe componeit A formed by the sul)ppressed mutaint (A-3 su-3) derived from the A-CRAI former, strain A-3, hadld aibnormatl activity ratios in the' thr'ee react('tionis (see reaction rates in table 5) aindl was less a(tive p(Ier unit A atntigenic materiall in the illdoleglycerol-phosphate reactions tlhan wa:s norman.l coml)onent A (27). This strain w-as exallmined further (53) in tests (lesigned to dleterminle whether or Inot suppression, in this case, hadl resulted in the formllation of at second A protein in a(ldlition to theimuta.nt A p)rotein, whether it hadl resulte(l in the formation of a new A protein whIiich repltced the mutant A proteinl, oIr wAhether the miiutaint protein was not atffected by the suppr)ssori5 mutation but an inhibitor of the ImutaIt prl)otein was removel. Througlh the use of )EAE-(ellulose columnllls aindl chromaitography in the presence of coomponent B, it N ,as lpossil)le to show that there ere tw-o A protetins in this supl)l)ressdl iiutaint, one which reseml )led( the A protein of the unsuppresse(l mutanit and the otherl, the minority coml)onent, with l)roperties siiilar to those of theA wildl-type Ak protein.…”

Section: Suppressor Genementioning

confidence: 97%

The Tryptophan Synthetase System 1

Yanofsky¹

1960

Bacteriological Reviews

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107

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tablished that the coupling of indole and serine would proceed in extracts and that the reaction was dependent on pyridoxal phosphate. The enzyme system catalyzing this reaction was named tryptophan synthetase (figure 1) (6). Throughout the early investigations by the group working with N. crassa, the relationship of their findings on various biosynthetic pathways to the mechanism of gene action was of primary concern, since the impetus for these investigations came from studies on the mechanism of gene action in other organisms (7, 8). Their observations through the years provided convincing evidence for a one-to-one relationship between gene and biochemical reaction, but the extension of this relationship to the enzvme level in well-characterized mutants was not realized for several years. For the most part, the reason for this delay was that those enzymes which had been and were being intensively studied by biochemists were not concerned with reactions that could be circumvented by exogenous nutritional supplements, and thus mutants presumably lacking these enzymes were not observed. It was no accident, therefore, that when a mutant was discovered which required tryptophan for growth but could not utilize indole as a substitute, AMitchell and Lein (9) examined extracts of this strain for tryptophan synthetase activity. It was found that 221 225 227 229 229 230 230 230 233 235 237 241 243 243 243

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“…Suppression of either an A-or a B-point mutant is always correlated with the formation of a corre sponding effective protein but, in every case as in Neurospora, the level of activity is lower than that of the wild-type strain (85). The A protein from one such suppressed mutant has been separated into two fractions; one is rich in A-CRM and the other in an A protein with "wild-type-like" activity (199) . The A protein from one such suppressed mutant has been separated into two fractions; one is rich in A-CRM and the other in an A protein with "wild-type-like" activity (199) .…”

Section: Suppressorsmentioning

confidence: 99%

“…It seems clear that the suppressors studied do not form an entire tryptophan synthetase protein because of the allelic specificity they exhibit (192,199). It seems clear that the suppressors studied do not form an entire tryptophan synthetase protein because of the allelic specificity they exhibit (192,199).…”

Section: Suppressorsmentioning

confidence: 99%

Gene Action

Yanofsky¹,

Lawrence²

1960

Annu. Rev. Microbiol.

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Evidence supporting the one gene-one protein hypothesis has increased rapidly in the past ten years. The development of techniques for the analysis of the amino acid sequences of proteins and protein fragments (1, 2) and mutational site sequences in genes (3, 4, 5) has opened the door to a direct experimental examination of the details of this relationship. In addition, the presentation of the Watson-Crick model of DNA (6) and the theoretical explorations of nucleotide coding (7 to 11) have provided a comforting theoretical background to questions of how the genetic material specifies the information essential for the assembling of the characteristic amino acid sequence of each protein. The experimental analysis of the precise mecha nism of cytoplasmic protein synthesis has led to an understanding of several major aspects of this process (see review by Novelli in this volume) .The previous history of the relationship of gene-to-protein has been re viewed in detail in recent papers (12, 13), and a list of some 50-odd examples of the effects of mutations on enzymes in 11 different organisms has been published within the last year (13). Therefore, the present paper will be con fined to a discussion of studies with well-analyzed gene-protein systems, and systems which show considerable promise for future investigation. Such studies are providing the gross information which will ultimately seek ex planation at the nucleotide and amino acid level. The discussion will be re stricted for the most part to microbial material. However, the mammalian hemoglobin system will also be discussed since it is proving to be a model for expectations and predictions of the effects of mutations on specific proteins. No attempt has been made to cover every paper on each subject but only those pertinent to the points discussed. In areas related to the main topics considered, general review articles are given as references.The word "gene" assumes different meanings according to the operations used in characterizing it (3). In this review the terms "gene" or "locus" will refer to a segment of the genetic material carrying the information for the 1 The survey of the literature pertaining to this review was concluded in February, 1960. 2 The following abbreviations will be used: CRM (cross-reacting material); DNA (deoxyribonubleic acid); RNA (ribonucleic acid); TPN (triphosphopyridine nucleo tide).

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The Formation of a New Enzymatically Active Protein as a Result of Suppression

Cited by 29 publications

References 9 publications

Mechanism Studies of Suppressor-Gene Action

Mechanism Studies of Suppressor-Gene Action

The Tryptophan Synthetase System 1

Gene Action

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