Differences in accumulation and phosphorylation of proteins in vegetatively growing and aggregation-competent cells of Dictyostelium discoideum

1991 ◽  
Vol 69 (10-11) ◽  
pp. 751-753
Author(s):  
S. Ramagopal
Keyword(s):  
Ribosomal Proteins ◽  
Staining Method ◽  
Cellular Slime Mold ◽  
Developmentally Regulated ◽  
Two Dimensional Gel Electrophoresis ◽  
Competent Cells ◽  
In Vivo Labeling ◽  
Cellular Slime ◽  
Silver Staining Method

A comparison of proteins from whole cell lysates of vegetative amoebae and aggregation-competent cells by high-resolution two-dimensional gel electrophoresis coupled with a sensitive silver staining method revealed distinct differences. In aggregation-competent cells, 16 proteins present in the vegetative amoebae disappeared, and 25 new proteins appeared. A few other proteins showed quantitative variation during the transition of vegetative amoebae to aggregation competence. Identification of phosphoproteins by in vivo labeling with [32P]orthophosphate showed that none of the developmentally regulated cellular proteins were modified. Phosphorylation was observed in four proteins. One protein was phosphorylated exclusively in aggregation-competent cells. The phosphorylation level of two other proteins was higher in aggregation-competent cells compared with vegetative amoebae. The data suggest that phosphorylation of cellular and certain ribosomal proteins may be regulated coordinately in Dictyostelium discoideum.Key words: cellular slime mold, cell differentiation, protein phosphorylation.

Subcellular distribution of ribosomal proteins in Dictyostelium discoideum

1990 ◽  
Vol 68 (5) ◽  
pp. 839-845
Author(s):  
S. Ramagopal
Keyword(s):  
Ribosomal Proteins ◽  
Large Subunit ◽  
Small Subunit ◽  
Cellular Slime Mold ◽  
Developmentally Regulated ◽  
Two Dimensional Gel Electrophoresis ◽  
Coomassie Blue ◽  
Cellular Slime ◽  
State Growth

The distribution of ribosomal proteins in monosomes, polysomes, the postribosomal cytosol, and the nucleus was determined during steady-state growth in vegetative amoebae. A partitioning of previously reported cell-specific ribosomal proteins between monosomes and polysomes was observed. L18, one of the two unique proteins in amoeba ribosomes, was distributed equally among monosomes and polysomes. However S5, the other unique protein, was abundant in monosomes but barely visible in polysomes. Of the developmentally regulated proteins, D and S6 were detectable only in polysomes and S14 was more abundant in monosomes. The cystosol revealed no ribosomal proteins. On staining of the nuclear proteins with Coomassie blue, about 18, 7 from 40S subunit and 11 from 60S subunit, were identified as ribosomal proteins. By in vivo labeling of the proteins with [35S]methionine, 24 of the 34 small subunit proteins and 33 of the 42 large subunit proteins were localized in the nucleus. For the majority of the ribosomal proteins, the apparent relative stoichiometry was similar in nuclear preribosomal particles and in cytoplasmic ribosomes. However, in preribosomal particles the relative amount of four proteins (S11, S30, L7, and L10) was two- to four-fold higher and of eight proteins (S14, S15, S20, S34, L12, L27, L34, and L42) was two- to four-fold lower than that of cytoplasmic ribosomes.Key words: cellular slime mold, cell-specific ribosomal proteins, nucleus, cytoplasm, two-dimensional gel electrophoresis.

Induction of cell-specific ribosomal proteins in aggregation-competent nonmorphogenetic Dictyostelium discoideum

1990 ◽  
Vol 68 (11) ◽  
pp. 1281-1287 ◽  
Author(s):  
S. Ramagopal
Keyword(s):  
Ribosomal Proteins ◽  
Cell Types ◽  
Growth Cycle ◽  
Logarithmic Phase ◽  
Cellular Slime Mold ◽  
Developmentally Regulated ◽  
Vegetative Cells ◽  
Competent Cells ◽  
Cellular Slime ◽  
Different Cell Types

Vegetatively growing amoebae, if shaken in a starvation (nonnutrient) buffer, acquire aggregation competence, but do not embark on a morphogenetic program. The quantitative variation of ribosomal proteins in vegetative and aggregation-competent cells was compared by labeling the different cell types with [35S]methionine. Vegetative cells were examined at various phases of the growth cycle. No changes could be detected in the content of ribosomes or the apparent stoichiometry of ribosomal proteins in growing cells. In stationary phase cells, the net ribosome content declined to 15% of that observed in logarithmic phase, but the relative amounts of individual ribosomal proteins were not altered. Although aggregation-competent cells contained 30% less ribosomes compared with logarithmic phase cells, the total fraction of newly made ribosomal proteins was the same in both. In contrast to vegetative cells, distinct changes were induced in the ribosomal proteins of aggregation-competent cells. The composition of ribosomes in aggregation-competent phase resembled in every respect that observed in spore cells. As reported earlier, changes were found in all 12 of the developmentally regulated ribosomal proteins. For the majority of newly made ribosomal proteins during aggregation competence, the stoichiometry was similar to that in logarithmically growing cells. However, the relative synthesis of some was particularly higher (13- to 46-fold for A and L; 3- to 8-fold for D, E, S24, L3, S6, and L4) compared with logarithmic phase cells. About 18 proteins, which included the cell-specific ribosomal proteins L18, S10, S14, S16, and L11, were synthesized in lesser amounts than in logarithmic phase cells. It is concluded that the attainment of aggregation competence is sufficient for the induction of spore cell specific ribosomal proteins in Dictyostelium discoideum.Key words: cellular slime mold, ribosomal proteins, development.

Acidic ribosomal proteins of Dictyostelium discoideum that show electrophoretic similarity to Escherichia coli proteins L7 and L12

1989 ◽  
Vol 67 (10) ◽  
pp. 712-718 ◽  
Author(s):  
S. Ramagopal
Keyword(s):  
Escherichia Coli ◽  
Dictyostelium Discoideum ◽  
Gel Electrophoresis ◽  
Ribosomal Proteins ◽  
Sodium Dodecyl ◽  
Slime Mold ◽  
Cellular Slime Mold ◽  
Two Dimensional ◽  
Cellular Slime ◽  
Acidic Proteins

This study documents the presence of three acidic proteins, A1 (pI 4.95), A2 (pI 4.85), and A3 (pI 4.70), in Dictyostelium discoideum ribosomes. All three proteins showed an apparent molecular mass of 13 000 by two-dimensional, sodium dodecyl sulfate gel electrophoresis. They were selectively released by treatment of ribosomes with 50% ethanol – 1 M NH4Cl. The amino acid compositions of A1, A2, and A3 were identical and indicated a predominant amount of alanine. All the above properties are shared by Escherichia coli proteins L7 and L12 and acidic ribosomal proteins in many eukaryotes. Unlike other eukaryotic systems, the acidic proteins of D. discoideum were found associated with the 40S rather than the 60S ribosomal subunit. Acidic proteins analogous in size and electrophoretic mobility to those of D. discoideum were also detected in several other cellular slime mold strains. Not one of the cellular slime mold acidic proteins reacted with antibodies to E. coli proteins L7 and L12 in immunodiffusion tests. In D. discoideum, the distribution of acidic proteins was altered during development. Amoebae contained all three proteins. In spores, A, was absent and the relative amounts of A2 and A3 were lower than in amoebae. In addition, nine other acidic ribosomal proteins exhibited differences between vegetative amoebae and spores.Key words: acidic ribosomal proteins, development, cellular slime mold, L7 and L12 proteins, two-dimensional gel electrophoresis.

scholarly journals Initial Proteome Analysis of Model Microorganism Haemophilus influenzae Strain Rd KW20

2003 ◽  
Vol 185 (15) ◽  
pp. 4593-4602 ◽  
Author(s):  
Eugene Kolker ◽  
Samuel Purvine ◽  
Michael Y. Galperin ◽  
Serg Stolyar ◽  
David R. Goodlett ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Gel Electrophoresis ◽  
Ribosomal Proteins ◽  
Protein Identification ◽  
Proteome Analysis ◽  
Tandem Mass ◽  
Two Dimensional ◽  
High Confidence ◽  
Two Dimensional Gel Electrophoresis

ABSTRACT The proteome of Haemophilus influenzae strain Rd KW20 was analyzed by liquid chromatography (LC) coupled with ion trap tandem mass spectrometry (MS/MS). This approach does not require a gel electrophoresis step and provides a rapidly developed snapshot of the proteome. In order to gain insight into the central metabolism of H. influenzae, cells were grown microaerobically and anaerobically in a rich medium and soluble and membrane proteins of strain Rd KW20 were proteolyzed with trypsin and directly examined by LC-MS/MS. Several different experimental and computational approaches were utilized to optimize the proteome coverage and to ensure statistically valid protein identification. Approximately 25% of all predicted proteins (open reading frames) of H. influenzae strain Rd KW20 were identified with high confidence, as their component peptides were unambiguously assigned to tandem mass spectra. Approximately 80% of the predicted ribosomal proteins were identified with high confidence, compared to the 33% of the predicted ribosomal proteins detected by previous two-dimensional gel electrophoresis studies. The results obtained in this study are generally consistent with those obtained from computational genome analysis, two-dimensional gel electrophoresis, and whole-genome transposon mutagenesis studies. At least 15 genes originally annotated as conserved hypothetical were found to encode expressed proteins. Two more proteins, previously annotated as predicted coding regions, were detected with high confidence; these proteins also have close homologs in related bacteria. The direct proteomics approach to studying protein expression in vivo reported here is a powerful method that is applicable to proteome analysis of any (micro)organism.

Synthesis of a ribosome-bound translatable poly(A)− mRNA during spore germination in Dictyostelium discoideum

1989 ◽  
Vol 35 (5) ◽  
pp. 573-577
Author(s):  
S. Ramagopal
Keyword(s):  
Dictyostelium Discoideum ◽  
Spore Germination ◽  
Gel Electrophoresis ◽  
Rna Synthesis ◽  
In Vitro Translation ◽  
Cellular Slime Mold ◽  
Free System ◽  
Cellular Slime

A distinct poly(A)− RNA sedimenting around 10–12S was identified during spore germination in Dictyostelium discoideum. Activated spores were labeled with [3H]uracil and the poly(A)− RNA was purified from ribosomal particles for analysis. In the spore swelling stage, 40 to 50% of the newly synthesized poly(A)− RNA was 10–12S RNA. This fraction diminished to one-half or one-fourth depending on the labeling period at the stage of amoeba emergence. The 10–12S RNA was associated with both monosomes and polysomes in vivo. Translation in a wheat germ cell-free system and gel electrophoresis demonstrated that the 10–12S RNA coded for a number of polypeptides, some of which were also represented among the in vitro products of poly(A)+ RNA. However, there were seven unique polypeptides (37.5, 28.2, 27.5, 23, 17.7, 17, and 14.2 kilodaltons) encoded exclusively by 10–12S RNA.Key words: cellular slime mold, RNA synthesis, development, poly(A)− mRNA, in vitro translation.

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