Synthesis of Enzymes During the Cell Cycle

Halvorson, Harlyn O.; Carter, B.L.A.; Tauro, P.

doi:10.1016/s0065-2911(08)60067-3

Cited by 79 publications

(27 citation statements)

References 179 publications

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“…Protein 6s was only slightly inhibited by temperature upshift and was not previously classified as a major heat shock protein, although it was substantially inhibited as a result of the manipulations inherent in the size fractionation procedure. DISCUSSION Although there have been reports of changes in many enzyme activities during the eucaryotic cell cycle (14,21,27; J. G. Yarger et al, in press), recent studies with S. cerevisiae (8)(9)(10)22) detected no changes in the synthesis of individual polypeptides and only two cases of cell cycle-periodic modification. Only histone synthesis was shown to be cell cycle regulated (20,30) in this earlier work.…”

Section: Resultsmentioning

confidence: 86%

Identification of Proteins Whose Synthesis Is Modulated During the Cell Cycle ofSaccharomyces cerevisiae

Lörincz¹,

Miller²,

Xuong³

et al. 1982

Mol. Cell. Biol.

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We examined the synthesis and turnover of individual proteins in the Saccharomyces cerevisiae cell cycle. Proteins were pulse-labeled with radioactive isotope (32S or 14C) in cells at discrete cycle stages and then resolved on two-dimensional gels and analyzed by a semiautomatic procedure for quantitating gel electropherogram-autoradiographs. The cells were obtained by one of three methods: (i) isolation of synchronous subpopulations of growing cells by zonal centrifugation; (ii) fractionation of pulse-labeled steady-state cultures according to cell age; and (iii) synchronization of cells with the mating pheromone, a-factor. In confirmation of previous studies, we found that the histones H4, H2A, and H2B were synthesized almost exclusively in the late Gl and early S phases. In addition, we identified eight proteins whose rates of synthesis were modulated in the cell cycle, and nine proteins (of which five, which may well be related, were unstable, with half-lives of 10 to 15 min) that might be regulated in the cell cycle by periodic synthesis, modification, or degradation. Based on the time of maximal labeling in the cell cycle and on experiments with a-factor and hydroxyurea, we assigned the cell cycle proteins to two classes: proteins in class I were labeled principally in early Gl phase and at a late stage of the cycle, whereas those in class II were primarily synthesized at times ranging from late Gl to mid S phase. At least one major control point for the cell cycle proteins occurred between "start" and early S phase. A set of stress-responsive proteins was also identified and analyzed. The rates of synthesis of these proteins were affected by certain perturbations that resulted during selection of synchronous cell populations and by heat shock.Understanding the molecular basis of the many cellular events which occur at discrete stages of the progress of cells from one division to the next is the central focus of research on the cell cycle. Saccharomyces cerevisiae has been developed as a model organism for studying eucaryotic cell cycle control (15-17, 34, 43). Genetic analysis has generated some of the basic ideas about functional pathways in the cell cycle and also provided material for further biochemical studies.In this paper, we report on a search for cell cycle-regulated proteins in S. cerevisiae. In an earlier analysis of the patterns of synthesis of S.cerevisiae proteins in the cell cycle (8-10, 22), almost 200 proteins were examined quantitatively after being separated on two-dimensional (2-t Present address:

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Section: Resultsmentioning

confidence: 86%

Identification of Proteins Whose Synthesis Is Modulated During the Cell Cycle ofSaccharomyces cerevisiae

Lörincz¹,

Miller²,

Xuong³

et al. 1982

Mol. Cell. Biol.

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“…The data suggested that over 30 enzymes, including the catabolic enzyme a-glucosidase, showed characteristic twofold jumps in activity with time in synchronized cultures (19,21,38,39,48). However, such data faceC a degree of criticism, in that as the cells were synchronized by induction (alternating cycles of nutritional starvation and release) or by selection (zonal centrifugation in a sucrose density gradient), there was chance for artifact (17,46,52).…”

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confidence: 99%

Synthesis of specific identified, phosphorylated, heat shock, and heat stroke proteins through the cell cycle of Saccharomyces cerevisiae.

Ludwig¹,

Foy²,

Elliott³

et al. 1982

Mol. Cell. Biol.

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The methods of centrifugal elutriation, two-dimensional gel electrophoresis, and dual isotopic labeling were applied to the study and identification of a number of purified yeast proteins. The location of polypeptide spots corresponding to specific proteins was determined on two-dimensional gels. A dual-label method was used to determine the rates of synthesis through the cell cycle of the identified proteins as well as to confirm the results of previous studies from our laboratory on unidentified proteins. The identified proteins, and the more generally defined phosphorylated, heat shock, and heat stroke proteins were found to follow the general pattern of exponential increase in rate of synthesis through the cell cycle. In addition, colorimetric enzyme activity assays were used to examine the catabolic enzyme ca-glucosidase (EC 3.2.1.20). Both the activity and synthesis of a-glucosidase were found to be nonperiodic with respect to the cell cycle. These data contrast with earlier reports of periodicity, which employed induction and selection synchrony to study enzyme expression through the yeast cell cycle.The cell cycles of eucaryotic organisms contain a number of distinct events which take place only once in each cell cycle and are restricted to a defined period. In the budding yeast Saccharomyces cerevisiae, such distinct, one-time events include: spindle pole body duplication and separation, bud emergence, DNA synthesis, nuclear migration, nuclear division, cytokinesis, and cell separation (23). In addition to distinct events, cells undergo an exponential increase in size through the cell cycle (23). In light of the temporal sequence of events through the cell cycle, one might expect to see temporal expression of specific protein products responsible for (or dependent upon) such events.Workers in this laboratory have approached the problem by applying the technique of centrifugal elutriation to the separation of asynchronous, exponentially growing populations of yeast cells into cell cycle specific fractions (14). During elutriation, cells in the separation chamber are acted upon by a centrifugal force which tends to sediment them. This force is opposed by a flow of liquid, and with increasing flow rate, cells of increasing size are washed from the chamber and collected into specific fractions. t Current address:

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“…Two hypotheses have been presented to explain step enzyme formation: the oscillatory repression model (Masters & Donachie, 1966) and the linear transcription model (Halvorson et al, 1971). We have not been able to distinguish between these models on our present data and the restrictions imposed by the conditions required for sporulation limit the controls which could be carried out using this system.…”

Section: Discussionmentioning

confidence: 99%

“…The times of appearance of these 'step enzymes' have been used as markers for the progress of the cell cycle. Using such markers, a distinction has been made between events which appear to be associated with growth (markers of the 'growth cycle') and those associated with cell division (markers of the ' DNA-division cycle') (Mitchison, 1973 ;Halvorson et al, 1971).…”

Section: Introductionmentioning

confidence: 99%

The Use of Step Enzymes as Markers During Meiosis and Ascospore Formation in Saccharomyces cerevisiae

Matur¹,

Berry²

1978

Journal of General Microbiology

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The activities of ornithine aminotransferase, sucrase and acid and alkaline phosphatases have been studied throughout sporulation in Saccharomyces cerevisiae. The same enzymes were monitored during synchronous vegetative growth. Each of these enzymes has been demonstrated to increase in a 'step' manner during both growth and sporulation. Alkaline phosphatase increased in a two-step manner whereas the others increased in a single step. The times of increase of these enzymes formed a similar sequence during both sporulation and growth. It has been proposed that these enzymes are under a common mechanism of control during growth and sporulation and that the sequence of enzyme appearance may be used as markers of the sporulation process.

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Synthesis of Enzymes During the Cell Cycle

Cited by 79 publications

References 179 publications

Identification of Proteins Whose Synthesis Is Modulated During the Cell Cycle ofSaccharomyces cerevisiae

Identification of Proteins Whose Synthesis Is Modulated During the Cell Cycle ofSaccharomyces cerevisiae

Synthesis of specific identified, phosphorylated, heat shock, and heat stroke proteins through the cell cycle of Saccharomyces cerevisiae.

The Use of Step Enzymes as Markers During Meiosis and Ascospore Formation in Saccharomyces cerevisiae

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