RESUMO
Amino acid sequences of the small subunit of ribulose-1,5-bisphosphate carboxylase (SSU) of Acetabularia cliftonii and A. mediterranea were derived from five cDNA sequences of each of the two species of algae and by direct amino acid sequence determination of the isolated protein. An homology of more than 96% between the proteins indicates the close relationship between the two algae. All ten cDNAs in the reading frame display the termination codons TAA and/or TAG at various positions, which seem to code for the amino acid glutamine when compared with the amino acid sequence from the mature protein. This is reminiscent of proteins from ciliates where TAA and TAG also code for glutamine.
Assuntos
Acetabularia/genética , Sequência de Bases , Clorófitas/genética , Códon , DNA/análise , Glutamina/genética , RNA Mensageiro , Ribulose-Bifosfato Carboxilase/genética , Homologia de Sequência do Ácido Nucleico , Sequência de Aminoácidos , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Polimorfismo de Fragmento de RestriçãoRESUMO
New phosphoproteins appear on the host erythrocyte membrane during Plasmodium berghei and P. chabaudi infection. Distinct proteins having similar properties and all distinguished by isoelectric points of less than 4.0 are identified. Associated with the erythrocyte membranes of P. berghei infected erythrocytes are two proteins with molecular masses of 65 and 46 kDa, whereas 93, 90 and 76 kDa proteins are observed during P. chabaudi infection. These new erythrocyte membrane associated proteins are all of parasite origin as indicated by metabolic labeling with proline and are synthesized during the ring stage of the asexual replicative cycle. Three of these proteins, the 93 kDa P. chabaudi protein and both P. berghei proteins, have been purified and the amino acid composition determined. All three are characterized by a relatively high proportion of aspartate and glutamate residues. Mono-and polyclonal antibodies were also raised against the same three purified proteins. No cross reactivity between these three proteins is observed, but one monoclonal antibody against the 65 kDa P. berghei crossreacts with a 27 kDa mouse erythrocyte protein. Immunofluorescence using the antibodies in combination with subcellular fractionation studies clearly shows that these phosphoproteins are associated with the host erythrocyte membrane and not the parasite.
Assuntos
Membrana Eritrocítica/análise , Eritrócitos/parasitologia , Fosfoproteínas/análise , Plasmodium berghei/fisiologia , Plasmodium/fisiologia , Animais , Anticorpos Monoclonais , Reações Cruzadas , Eletroforese em Gel de Poliacrilamida , Imunofluorescência , Interações Hospedeiro-Parasita , Imunoensaio , Ponto Isoelétrico , Proteínas de Membrana/análise , Proteínas de Membrana/biossíntese , Peso Molecular , Fosfoproteínas/biossíntese , Plasmodium/crescimento & desenvolvimento , Plasmodium berghei/crescimento & desenvolvimentoRESUMO
In contrast to other plants the plastid genome of Acetabularia is larger in size and shows a high degree of variability. This study on the chloroplast-encoded large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase demonstrates that strongly conserved areas also exist in the plastid genome of the Dasycladaceae. Searching for differences in the amino acid sequence of the large subunit from Acetabularia mediterranea and Acicularia schenckii, proteolytic peptides which differ in their elution behaviour in reverse-phase high-performance liquid chromatography were sequenced. Only six amino acids were found to be exchanged in the large subunit from these two species. Since these two species diverged approx. 150 million years ago, these results imply that 0.84 amino-acid exchanges per 100 amino acids have occurred in 10(8) years, underlining the strong conservatism of the large subunit.
