Methylation of elongation factor 1 alpha from the fungus Mucor.

Abstract

A basic protein from the dimorphic fungus Mucor racemosus, found to be highly methylated, is shown to be protein synthesis elongation factor la. This protein is the most abundant protein in hyphal cells but is less abundant in yeast cells. It is posttranslationally methylated with the formation of mono-, di-, and trimethyllysine at as many as 16 sites. Nearly 20% of the 44 lysine residues of elongation factor la from mycelia are modified while those from sporangiospores are virtually unmethylated.Mucor racemosus is a dimorphic fungus that exists in either yeast or hyphal forms. These changes in morphology are accompanied by changes in the translational system, evidenced by an acceleration in the rate of peptide bond formation (1, 2) and by a change in the level of phosphorylation of a ribosomal protein (3). In the course of studying posttranslational modifications in the fungus, we resolved several methylated peptides by using two-dimensional polyacrylamide gel electrophoresis. We have now identified one of these peptides as the a subunit of protein synthesis elongation factor 1 (EF-la), the functional equivalent of prokaryotic elongation factor Tu (EF-Tu) (4). EFTu from Salmonella typhimurium and Escherichia coli is methylated (5, 6), and that in E. coli contains a single methyllysine at position 56.In certain proteins, acidic amino acids are methylated by a reversible carboxymethylation reaction, examples of which have been shown to play roles in bacterial chemotaxis (7-9), leukocyte chemotaxis (10-12), and hormone secretion (13). The methylation of basic amino acids occurs at the E-amino group of lysine, the guanidinium group of arginine, or the imidazole group of histidine (14). Although these reactions show a high degree of specificity, there has been no clear functional role assigned to the presence ofmethylated basic amino acids. Methylated basic amino acids occur in histones (15,16,17)

Regulation of protein synthesis factor EF-1 alpha in Mucor racemosus.

“…A constant, high level of EF-la mRNA during the time that activity was changing raised the question of whether the EF-la protein was being synthesized at similarly constant levels. This question was approached by germinating spores in [35S]methionine and determining the relative amount of EF-la protein from its unique position in a two-dimensional polyacrylamide gel (9). We found that the amount of EF-la protein, measured as a proportion of total cellular protein, changed little during spore germination (Table 1) and did not reflect the change in specific activity of the factor.…”

“…These alternative forms of growth, as well as the process of spore germination, are accompanied by differences in the translational system. Among these are differences in the rate of peptide bond formation (18,19), the extent of phosphorylation of ribosomal protein S-6 (11,12), and the methylation of the elongation factor EF-la (9). In the latter case, we have found that of the 44 lysine residues, 8 or 9 are methylated when the organism grows in the mycelial form (9).…”

“…Among these are differences in the rate of peptide bond formation (18,19), the extent of phosphorylation of ribosomal protein S-6 (11,12), and the methylation of the elongation factor EF-la (9). In the latter case, we have found that of the 44 lysine residues, 8 or 9 are methylated when the organism grows in the mycelial form (9). The extent of methylation is less in the yeast form, and spores contain an EF-la that is essentially nonmethylated.…”

Compartmentalization and actin binding properties of ABP‐50: The elongation factor‐1 alpha of Dictyostelium

“…Methylation of lysine residues is another posttranslational modification of EF-1 alpha [Hiatt et al, 1982;Coppard et al, 1983;Fonzi et al, 1985;Sherman and Syphered, 19891 and it has been correlated with cell differentiation and increases in protein synthesis [Coppard et al, 1983;Fonzi et al, 1985;Sherman and Syphered, 19891. In this regard it is interesting that the sequence around lysine 309 in ABP-50, + G T P~ f + G T P~ when GTP was added to ABP-50 for 10 min prior to incubation with F-actin; +GTPh, when ABP-50 was pre-incubated with F-actin for 10 min prior to the addition of GTP.…”

Expression of an EF-1α-like Rat cDNA, S1, in Escherichia coli and Production of a Rabbit Polyclonal Antiserum to the Recombinant Protein

“…EF-l (\' III fungus Mucor racell/OSIiS has been previously shown to be post tnlll! '>latlOnall y modi lied hy \11ethylation of Iysiue rcsidues (Hiatt et al, 1982).…”