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Correlation between tRNA population and amino acid composition of proteins in plants
Plant Science Letters, 21 (1981) 15--21 © Elsevier/North-Holland Scientific Publishers Ltd.
15
CORRELATION BETWEEN tRNA POPULATION AND AMINO ACID COMPOSITION OF PROTEINS IN PLANTS
W O J C I E C H KEDZIERSKI
Institute of Biochemistry, Academy of Agriculture, Wolynska 35, 60-63 7 Poznan (Poland)
(Received September 1st, 1980) (Revision received October 27th, 1980) (Accepted October 27th, 1980)
SUMMARY
Transfer RNAs were isolated from sprouts after l
INTRODUCTION
The functional adaptation of tRNA population to protein synthesis is seen in procaryotes, yeast and animal non
16
correlation from a statistical point o f view, between the levels of 9 t R N A species, which have been determined, and amino acid contents of proteins either in endosperm (linear correlation coefficient r = 0.47, significance lower than 90%) or in e m b r y o (correlation coefficient r = 0.28). This paper indicates, that such statistically significant relationship does occur in lupine, potato and wheat sprouts. MATERIALS AND METHODS
Lupinus luteus L. (cv. Express) seeds and Triticum aestivum L. (cv. Jana) grains were imbibed in water at 2°C for 5 h, then germinated on wet cellulose in the dark at 25°C. The sprouts of 1-day seedlings were removed b y hand and used as a source of t R N A preparation and postribosomal supernatant. Solanum tuberosum L. (cv. Lenino) tubers harvested in October were stored at 5°C for 4 months, then at 25°C for 3 days. Approximately 1 g samples of tubers containing sprouts were removed with 8 mm cork borer and used as a source o f t R N A preparation and post-ribosomal supernatant. Transfer RNAs and wheat aminoacyl-tRNA synthetases were isolated as described previously for lupine t R N A [4] and lupine enzymes [ 5]. The fraction of proteins precipitated between 50% and 70% of ammonium sulfate saturation contained the activities of alanyl- aspartyl-, glutamyl-, methionyl-, seryl- and tyrosyl-tRNA synthetases. The other aminoacylt R N A synthetases were present in the fraction precipitating between 30% and 50% of ammonium sulfate saturation. Amino acid acceptor assay. All assays were carried o u t in a final reaction volume of 50 ~1 containing 100 mM Hepes (pH 7.8), 50 mM KCI, 10 mM MgCI~, 2.5 mM ATP, 1 nmol of the appropriate ~4C-labelled amino acid, 0.05 mg of wheat enzyme preparation and different amounts of t R N A (0.05--0.5 A260 unit). Following 20 rain incubation at 30°C aliquots of 35 ~1 were taken~t~d applied to Whatman 3MM filter paper discs (2.3 cm in diameter). The discs were washed as described previously [ 5] and c o u n t e d for radioactivity. Under the conditions used the incubation mixtures contained the excess o f enzyme preparations. The reactions reached a plateau for the highest t R N A concentration usually after 10 min incubation. No decrease in amounts of aminoacyl-tRNA formed was observed during p r ~ longed 30 rain incubation time. Amino acid acceptor activity of the t R N A preparation was calculated from the slope of the linear relationship between the amounts of aminoacyl-tRNA formed and the amounts of t R N A added to the incubation mixture. Level of t R N A aminoacylation in vivo was determined as described previously [6]. Amino acid composition o f proteins. Plant material (1 g) was homogenized in a cooled mortar and extracted with 20 ml of 60 mM KH2PO4 buffer (pH 6.8). Following centrifugation at 20 000 × g for 30 rain the
17
homogenate was centrifuged at 120 000 × g for 1.5 h. The supernatant fraction was dialysed against 60 mM KH~PO4 buffer (pH 6.8) and hydrolysed in 6 M HC1 for 24 h. Amino acid analyses were performed with a Microtechna {Czechoslovakia) auto-analyser, model AAA-881. RESULTS
Transfer RNAs were isolated from sprouts after l
done for different tRNA
concentrations
Amino acid
Lupine a
Potato a
Wheat a
Ala Arg AsN Asp GlN Glu Gly His Ile Leu Lys Met Phe Pro Set Thr Trp Tyr Val
35 30 47 21.5 18 16 58 7.5 42 65 17 11 27 7 27 22 30 43 41
50± 36± 42± 24 ± 25± 31 ± 46± 11 ~ 39 ± 69 ± 18± 22~24± 8± 29 ~ 28 ± 34 ± 39 ~ 46 +
53 47 42 19 26 19.5 75 18 34 61 27 23 31 14 23 29 28 21 48
± 2.5 ± 1.8 +- 1.9 ± 1.0 ± 1.5 ± 0.5 ± 3.0 ± 0.3 ± 1.3 ± 0.9 ± 0.5 ~ 0.8 ± 0.6 ± 0.7 ± 0.8 ± 1.6 ± 2.4 ~ 1.3 ± 0.6
aExpressed as pmol A A per A2~ 0 unit of t R N A ± S.E.
3.6 1.3 2.1 1.1 2.6 1.5 1.8 0.8 2.4 0.6 0.6 1.2 0.3 0.4 1.3 1.0 2.7 1.4 1.4
± 2.9 ± 1.2 ± 1.5 ± 0.5 ± 2.2. ± 0.9 ± 2.2 ± 0.5 • 1.9 ± 0.4 ± 0.5 ± 1.9 ~ 0.8 *- 0 . 3 -+. 0 . 7 *- 0 . 8 ± 2.8 ~ 1.8 ± 1.0
18 disappear during lupine seed germination [7] simultaneously with the significant increase in the levels of tRNA aminoacylation [4--6]. Since chloroplast and bacterial tRNAs are similar [ 8,9], we have studied the acylation of plant tRNA preparations with bacterial enzymes. That has allowed us to evaluate quantitatively the presence of chloroplast tRNAs in the tRNA preparations by aminoacylation with phenylalanyland tyrosyl-tRNA synthetases from E. coli, which do not acylate cytoplasmic tRNAs (our unpublished data). The results presented in Table II indicate that tRNA preparations isolated from sprouts after 1-day germination of lupine and wheat seeds and after 3-day sprouting of potato tubers contain low amounts of chloroplast tRNAs. Since the contribution of mitochondrial tRNAs to the plant total tRNA seems to be also low (being 6.2% for example in 7~lay-old lupine cotyledons [10]) we assume that the acceptor activities of tRNAs given in Table I describe the populations of biologically active tRNA molecules present mainly in cytoplasm. The tRNA populations were then compared to the amino acid compositions in the post-ribosomal supernatant fractions from sprouts (Table III). That comparison of the relative amounts of amino acids in soluble proteins with the amounts of 14 corresponding tRNA species indicates the good correlation of these two parameters in plant mate.-'ials. The linear correlation coefficients are 0.71 for wheat, and 0.60 and 0.55 for lupine and potato respectively. The correlation is statistically significant according to Student's test. The significance is more than 99% for wheat and more than 95% for lupine and potato. Since tRNA populations were also determined for cotton by Merrick and Dure [11] and amino acid compositions of proteins by Elmore and King [12] we were able to calculate the correlation in cotton seeds. That correlation is higher, if amino acid compositions of non-storage proteins
TABLE II ACCEPTOR ACTIVITIES OF PLANT tRNA PREPARATIONS DETERMINED WITH PHENYLALANYL- AND TYROSYL-tRNA SYNTHETASES FROM E. COLI WHICH ACYLATE ORGANELLAR tRNAS ONLY In brackets these acceptor activities were compared to the activities measured with wheat aminoacyl-tRNA synthetases (assumed as 100%). Values are means of three replicates.
Source of tRNA Lupine Potato Wheat
Acceptor activity pmol Phe per A,60 unit of tRNA
pmol Tyr per A~0 unit of tRNA
2.2 (8%) 2.8 (12%) 3.2 (10%)
2.3 (5%) 1.2 (3%) 2.3 (11%)
19
TABLE III AMINO ACID COMPOSITION OF SOLUBLE PROTEINS OF POST-RIBOSOMAL SUPERNATANTS ISOLATED FROM SPROUTS AFTER 1-DAY GERMINATION OF LUPINE AND WHEAT SEEDS AND AFTER 3-DAY SPROUTING OF POTATO TUBERS Amino acid
Ala Arg Asx Glx Gly His Ile
Leu Lys Met Phe
Pro Set Thr Tyr Val
Lupine
Potato
Wheat
(%tool)
(%mol)
(%tool)
7.5 5.3 10.3 17.8 8.2 3.5 3.8 7.9 6.2 1.7 3.7 4.1 6.6 4.9 3.1 5.4
8.5 3.2 11.7 10.0 9.8 1.8 4.2 8.2 6.7 2.1 4.6 5.1 8.2 5.9 3.7 6.3
10.8 4.7 10.3 13.0 10.2 2.0 3.4 7.1 6.4 2.2 3.7 5.2 6.8 5.6 2.9 5.7
are taken into consideration (r = 0.58, significance over 95%) than the composition o f storage proteins (r = 0.40, significance 90%). On the base o f the above observations we can assume t h a t the t R N A populations are adjusted to tbe frequency of amino acids in soluble proteins also in higher plants in a way similar to the relations observed in E. coli, yeast and animal tissues [1]. DISCUSSION Theory of functional adaptation o f the tRNA population [ 1 ] is based on the observation t h a t there is a quantitative relationship existing between the frequency o f amino acids in proteins and the amounts of corresponding t R N A species. This regulation p h e n o m e n o n has been found in animal tissues which synthesize proteins with an unusual amino acid composition, such as the silkgland o f B o m b y x mori [13], bovine lens cells [14], m a m m a r y glands [ 15], rabbit reticulocytes [ 16], rat and chicken collagenous tissues [17,18]. This adaptation has also been observed in procaryotes, yeast and rat liver [1,19]. In all these cases the high value of the correlation coefficient (r = 0.63--0.99) indicates a good correlation between t R N A population and amino acid composition of synthesized proteins [ 1 ]. The results presented here show t h a t the a m o u n t s o f tRNAs correlate also with the frequency o f amino acids in proteins in higher plants. These
20 correlations are true for most t R N A species with a few exceptions however. And so the relatively low levels of t R N A Phe and t R N A Lys in all plants, t R N A His in lupine and relatively high levels of t R N A Leu do not fit well the linear correlation. This m a y be due to other non-ribosomal functions of tRNAs. The deviations could also arise on the experimental basis, since the t R N A acceptor activities determined can be lower than the amounts of corresponding t R N A s especially in a case of most unstable aminoacylt R N A molecules. Despite these limitations, which do not favour the correlation, the results presented here show such statisticallysignificant correlation between t R N A populations and the amino acid compositions of proteins of post-ribosomal supernatants occurring in higher plants. Also the differences in the acceptor activitiesof several species of t R N A in maize endosperm and embryo, together with the changes in relative amounts of iso-accepting tRNAs, support the theory of adaptation of t R N A population to protein synthesis [3], although the linear correlation of frequency of amino acids in proteins and the amounts of 9 corresponding t R N A species seems to be moderate. In that case the higher accepting activities of glutamine, alanine and leucine t R N A s in the endosperm as compared to the embryo, correspond with the fact, that the endosperm is mainly engaged in synthesis of rein, rich in glutarnine, leucine, alanine and proline [3]. Although the correlation between t R N A population and amino acid contents of proteins occurs in procaryotes, animals, yeast and also in plants, the mechanism of t R N A adjustment, constitutive or adaptive, is not known. It seems however to play an important role in optimizing accuracy [20] and efficiency of translation. ACKNOWLEDGEMENTS The interest and help of Professor Jerry Pawelkiewicz are gratefully acknowledged. This research was supported by Polish Academy of Sciences within the project 09.7.-1.2.5. REFERENCES 1 2 3 4 5 6 7 8 9 10 11
J.P. Garel, J. Theor. Biol., 43 (1974) 211. R.D. Norris, P.J. Lea and L. Fowden, Phytochemistry, 14 (1975) 1683. A. Viotti, C. Balducci and J.H. Well, Biochim. Biophys. Acta, 517 (1978) 125. W. Kedzierski, T. Sulewski and J. Pawelkiewicz, Plant Sci. Left., 14 (1979) 373. W. Kedzierski and J. Pawelkiewicz, Phytochemistry, 16 (1977) 503. W. Kedzierski, H. Augustynisk and J. Pawelkiewicz, Planta, 147 (1980) 439. T. Dziegielewski and J. Pawelkiewicz, Bull. Acad. Polon. Sci. Set. Biol., 25 (1977) 433. P. Guillemaut and J.H. WeU, Biochim. Biophya Acta, 407 (1975) 240. P. Guillemaut and G. Keith, FEBS Lett., 84 (1977) 351. H. Augustyniak and J. Pawelkiewicz, Acta Biochim. PolorL, 25 (1978) 91. W. Merrick and L.S. Dure, J. Biol. Chem., 247 (1972) 7988.
21 12 13 14 15 16 17 18 19 20
C.D. Elmore and E.E. King, Plant Physiol., 62 (1978) 531. J.P. Garel, P. Mandel, G. Chavancy and J. Daillie, FEBS Lett., 7 (1970) 327. J.P. Garel, N. Virmaux and P. Mandel, Bull. Soc. Chim. Biol., 52 (1970) 987. A. Elska, G. Matsuka, U. Matiash, I. Nasarenko and N. Semenova, Biochim. Biophys. Acta, 247 (1971) 430. D.W.E. Smith and A.L. McNamara, Science, 171 (1971) 1040. P.H. M~enpi~ and J. Ahonen, Biochem. Biophys. Res. Commun., 49 (1972) 179. P.J. Christner and J. Rosenbloom, Arch. Biochem. Biophys., 172 (1976) 399. G. Chavancy, A. Chevallier, A. Fournier and J.P. Garel, Biochimie, 61 (1979) 71. W.M. Holmes, G.W. Hatfield and E. Goldman, J. Biol. Chem., 253 (1978) 3482.
15
CORRELATION BETWEEN tRNA POPULATION AND AMINO ACID COMPOSITION OF PROTEINS IN PLANTS
W O J C I E C H KEDZIERSKI
Institute of Biochemistry, Academy of Agriculture, Wolynska 35, 60-63 7 Poznan (Poland)
(Received September 1st, 1980) (Revision received October 27th, 1980) (Accepted October 27th, 1980)
SUMMARY
Transfer RNAs were isolated from sprouts after l
INTRODUCTION
The functional adaptation of tRNA population to protein synthesis is seen in procaryotes, yeast and animal non
16
correlation from a statistical point o f view, between the levels of 9 t R N A species, which have been determined, and amino acid contents of proteins either in endosperm (linear correlation coefficient r = 0.47, significance lower than 90%) or in e m b r y o (correlation coefficient r = 0.28). This paper indicates, that such statistically significant relationship does occur in lupine, potato and wheat sprouts. MATERIALS AND METHODS
Lupinus luteus L. (cv. Express) seeds and Triticum aestivum L. (cv. Jana) grains were imbibed in water at 2°C for 5 h, then germinated on wet cellulose in the dark at 25°C. The sprouts of 1-day seedlings were removed b y hand and used as a source of t R N A preparation and postribosomal supernatant. Solanum tuberosum L. (cv. Lenino) tubers harvested in October were stored at 5°C for 4 months, then at 25°C for 3 days. Approximately 1 g samples of tubers containing sprouts were removed with 8 mm cork borer and used as a source o f t R N A preparation and post-ribosomal supernatant. Transfer RNAs and wheat aminoacyl-tRNA synthetases were isolated as described previously for lupine t R N A [4] and lupine enzymes [ 5]. The fraction of proteins precipitated between 50% and 70% of ammonium sulfate saturation contained the activities of alanyl- aspartyl-, glutamyl-, methionyl-, seryl- and tyrosyl-tRNA synthetases. The other aminoacylt R N A synthetases were present in the fraction precipitating between 30% and 50% of ammonium sulfate saturation. Amino acid acceptor assay. All assays were carried o u t in a final reaction volume of 50 ~1 containing 100 mM Hepes (pH 7.8), 50 mM KCI, 10 mM MgCI~, 2.5 mM ATP, 1 nmol of the appropriate ~4C-labelled amino acid, 0.05 mg of wheat enzyme preparation and different amounts of t R N A (0.05--0.5 A260 unit). Following 20 rain incubation at 30°C aliquots of 35 ~1 were taken~t~d applied to Whatman 3MM filter paper discs (2.3 cm in diameter). The discs were washed as described previously [ 5] and c o u n t e d for radioactivity. Under the conditions used the incubation mixtures contained the excess o f enzyme preparations. The reactions reached a plateau for the highest t R N A concentration usually after 10 min incubation. No decrease in amounts of aminoacyl-tRNA formed was observed during p r ~ longed 30 rain incubation time. Amino acid acceptor activity of the t R N A preparation was calculated from the slope of the linear relationship between the amounts of aminoacyl-tRNA formed and the amounts of t R N A added to the incubation mixture. Level of t R N A aminoacylation in vivo was determined as described previously [6]. Amino acid composition o f proteins. Plant material (1 g) was homogenized in a cooled mortar and extracted with 20 ml of 60 mM KH2PO4 buffer (pH 6.8). Following centrifugation at 20 000 × g for 30 rain the
17
homogenate was centrifuged at 120 000 × g for 1.5 h. The supernatant fraction was dialysed against 60 mM KH~PO4 buffer (pH 6.8) and hydrolysed in 6 M HC1 for 24 h. Amino acid analyses were performed with a Microtechna {Czechoslovakia) auto-analyser, model AAA-881. RESULTS
Transfer RNAs were isolated from sprouts after l
done for different tRNA
concentrations
Amino acid
Lupine a
Potato a
Wheat a
Ala Arg AsN Asp GlN Glu Gly His Ile Leu Lys Met Phe Pro Set Thr Trp Tyr Val
35 30 47 21.5 18 16 58 7.5 42 65 17 11 27 7 27 22 30 43 41
50± 36± 42± 24 ± 25± 31 ± 46± 11 ~ 39 ± 69 ± 18± 22~24± 8± 29 ~ 28 ± 34 ± 39 ~ 46 +
53 47 42 19 26 19.5 75 18 34 61 27 23 31 14 23 29 28 21 48
± 2.5 ± 1.8 +- 1.9 ± 1.0 ± 1.5 ± 0.5 ± 3.0 ± 0.3 ± 1.3 ± 0.9 ± 0.5 ~ 0.8 ± 0.6 ± 0.7 ± 0.8 ± 1.6 ± 2.4 ~ 1.3 ± 0.6
aExpressed as pmol A A per A2~ 0 unit of t R N A ± S.E.
3.6 1.3 2.1 1.1 2.6 1.5 1.8 0.8 2.4 0.6 0.6 1.2 0.3 0.4 1.3 1.0 2.7 1.4 1.4
± 2.9 ± 1.2 ± 1.5 ± 0.5 ± 2.2. ± 0.9 ± 2.2 ± 0.5 • 1.9 ± 0.4 ± 0.5 ± 1.9 ~ 0.8 *- 0 . 3 -+. 0 . 7 *- 0 . 8 ± 2.8 ~ 1.8 ± 1.0
18 disappear during lupine seed germination [7] simultaneously with the significant increase in the levels of tRNA aminoacylation [4--6]. Since chloroplast and bacterial tRNAs are similar [ 8,9], we have studied the acylation of plant tRNA preparations with bacterial enzymes. That has allowed us to evaluate quantitatively the presence of chloroplast tRNAs in the tRNA preparations by aminoacylation with phenylalanyland tyrosyl-tRNA synthetases from E. coli, which do not acylate cytoplasmic tRNAs (our unpublished data). The results presented in Table II indicate that tRNA preparations isolated from sprouts after 1-day germination of lupine and wheat seeds and after 3-day sprouting of potato tubers contain low amounts of chloroplast tRNAs. Since the contribution of mitochondrial tRNAs to the plant total tRNA seems to be also low (being 6.2% for example in 7~lay-old lupine cotyledons [10]) we assume that the acceptor activities of tRNAs given in Table I describe the populations of biologically active tRNA molecules present mainly in cytoplasm. The tRNA populations were then compared to the amino acid compositions in the post-ribosomal supernatant fractions from sprouts (Table III). That comparison of the relative amounts of amino acids in soluble proteins with the amounts of 14 corresponding tRNA species indicates the good correlation of these two parameters in plant mate.-'ials. The linear correlation coefficients are 0.71 for wheat, and 0.60 and 0.55 for lupine and potato respectively. The correlation is statistically significant according to Student's test. The significance is more than 99% for wheat and more than 95% for lupine and potato. Since tRNA populations were also determined for cotton by Merrick and Dure [11] and amino acid compositions of proteins by Elmore and King [12] we were able to calculate the correlation in cotton seeds. That correlation is higher, if amino acid compositions of non-storage proteins
TABLE II ACCEPTOR ACTIVITIES OF PLANT tRNA PREPARATIONS DETERMINED WITH PHENYLALANYL- AND TYROSYL-tRNA SYNTHETASES FROM E. COLI WHICH ACYLATE ORGANELLAR tRNAS ONLY In brackets these acceptor activities were compared to the activities measured with wheat aminoacyl-tRNA synthetases (assumed as 100%). Values are means of three replicates.
Source of tRNA Lupine Potato Wheat
Acceptor activity pmol Phe per A,60 unit of tRNA
pmol Tyr per A~0 unit of tRNA
2.2 (8%) 2.8 (12%) 3.2 (10%)
2.3 (5%) 1.2 (3%) 2.3 (11%)
19
TABLE III AMINO ACID COMPOSITION OF SOLUBLE PROTEINS OF POST-RIBOSOMAL SUPERNATANTS ISOLATED FROM SPROUTS AFTER 1-DAY GERMINATION OF LUPINE AND WHEAT SEEDS AND AFTER 3-DAY SPROUTING OF POTATO TUBERS Amino acid
Ala Arg Asx Glx Gly His Ile
Leu Lys Met Phe
Pro Set Thr Tyr Val
Lupine
Potato
Wheat
(%tool)
(%mol)
(%tool)
7.5 5.3 10.3 17.8 8.2 3.5 3.8 7.9 6.2 1.7 3.7 4.1 6.6 4.9 3.1 5.4
8.5 3.2 11.7 10.0 9.8 1.8 4.2 8.2 6.7 2.1 4.6 5.1 8.2 5.9 3.7 6.3
10.8 4.7 10.3 13.0 10.2 2.0 3.4 7.1 6.4 2.2 3.7 5.2 6.8 5.6 2.9 5.7
are taken into consideration (r = 0.58, significance over 95%) than the composition o f storage proteins (r = 0.40, significance 90%). On the base o f the above observations we can assume t h a t the t R N A populations are adjusted to tbe frequency of amino acids in soluble proteins also in higher plants in a way similar to the relations observed in E. coli, yeast and animal tissues [1]. DISCUSSION Theory of functional adaptation o f the tRNA population [ 1 ] is based on the observation t h a t there is a quantitative relationship existing between the frequency o f amino acids in proteins and the amounts of corresponding t R N A species. This regulation p h e n o m e n o n has been found in animal tissues which synthesize proteins with an unusual amino acid composition, such as the silkgland o f B o m b y x mori [13], bovine lens cells [14], m a m m a r y glands [ 15], rabbit reticulocytes [ 16], rat and chicken collagenous tissues [17,18]. This adaptation has also been observed in procaryotes, yeast and rat liver [1,19]. In all these cases the high value of the correlation coefficient (r = 0.63--0.99) indicates a good correlation between t R N A population and amino acid composition of synthesized proteins [ 1 ]. The results presented here show t h a t the a m o u n t s o f tRNAs correlate also with the frequency o f amino acids in proteins in higher plants. These
20 correlations are true for most t R N A species with a few exceptions however. And so the relatively low levels of t R N A Phe and t R N A Lys in all plants, t R N A His in lupine and relatively high levels of t R N A Leu do not fit well the linear correlation. This m a y be due to other non-ribosomal functions of tRNAs. The deviations could also arise on the experimental basis, since the t R N A acceptor activities determined can be lower than the amounts of corresponding t R N A s especially in a case of most unstable aminoacylt R N A molecules. Despite these limitations, which do not favour the correlation, the results presented here show such statisticallysignificant correlation between t R N A populations and the amino acid compositions of proteins of post-ribosomal supernatants occurring in higher plants. Also the differences in the acceptor activitiesof several species of t R N A in maize endosperm and embryo, together with the changes in relative amounts of iso-accepting tRNAs, support the theory of adaptation of t R N A population to protein synthesis [3], although the linear correlation of frequency of amino acids in proteins and the amounts of 9 corresponding t R N A species seems to be moderate. In that case the higher accepting activities of glutamine, alanine and leucine t R N A s in the endosperm as compared to the embryo, correspond with the fact, that the endosperm is mainly engaged in synthesis of rein, rich in glutarnine, leucine, alanine and proline [3]. Although the correlation between t R N A population and amino acid contents of proteins occurs in procaryotes, animals, yeast and also in plants, the mechanism of t R N A adjustment, constitutive or adaptive, is not known. It seems however to play an important role in optimizing accuracy [20] and efficiency of translation. ACKNOWLEDGEMENTS The interest and help of Professor Jerry Pawelkiewicz are gratefully acknowledged. This research was supported by Polish Academy of Sciences within the project 09.7.-1.2.5. REFERENCES 1 2 3 4 5 6 7 8 9 10 11
J.P. Garel, J. Theor. Biol., 43 (1974) 211. R.D. Norris, P.J. Lea and L. Fowden, Phytochemistry, 14 (1975) 1683. A. Viotti, C. Balducci and J.H. Well, Biochim. Biophys. Acta, 517 (1978) 125. W. Kedzierski, T. Sulewski and J. Pawelkiewicz, Plant Sci. Left., 14 (1979) 373. W. Kedzierski and J. Pawelkiewicz, Phytochemistry, 16 (1977) 503. W. Kedzierski, H. Augustynisk and J. Pawelkiewicz, Planta, 147 (1980) 439. T. Dziegielewski and J. Pawelkiewicz, Bull. Acad. Polon. Sci. Set. Biol., 25 (1977) 433. P. Guillemaut and J.H. WeU, Biochim. Biophya Acta, 407 (1975) 240. P. Guillemaut and G. Keith, FEBS Lett., 84 (1977) 351. H. Augustyniak and J. Pawelkiewicz, Acta Biochim. PolorL, 25 (1978) 91. W. Merrick and L.S. Dure, J. Biol. Chem., 247 (1972) 7988.
21 12 13 14 15 16 17 18 19 20
C.D. Elmore and E.E. King, Plant Physiol., 62 (1978) 531. J.P. Garel, P. Mandel, G. Chavancy and J. Daillie, FEBS Lett., 7 (1970) 327. J.P. Garel, N. Virmaux and P. Mandel, Bull. Soc. Chim. Biol., 52 (1970) 987. A. Elska, G. Matsuka, U. Matiash, I. Nasarenko and N. Semenova, Biochim. Biophys. Acta, 247 (1971) 430. D.W.E. Smith and A.L. McNamara, Science, 171 (1971) 1040. P.H. M~enpi~ and J. Ahonen, Biochem. Biophys. Res. Commun., 49 (1972) 179. P.J. Christner and J. Rosenbloom, Arch. Biochem. Biophys., 172 (1976) 399. G. Chavancy, A. Chevallier, A. Fournier and J.P. Garel, Biochimie, 61 (1979) 71. W.M. Holmes, G.W. Hatfield and E. Goldman, J. Biol. Chem., 253 (1978) 3482.