title: Large complexes of beta-poly(L-malate) with DNA polymerase alpha, histones, and other proteins in nuclei of growing plasmodia of Physarum polycephalum.
abstract: Of the various cell types in the life cycle of Physarum polycephalum, only the growing plasmodium contains the unusual polyester beta-poly(L-malate). The nuclei exhibit large complexes of this polymer with nuclear proteins, among them DNA polymerase alpha, histones, and HMG-like proteins. The complexes are indicated by the results of size exclusion chromatography and chemical cross-linking with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDC). After hydroxylaminolysis of the cross-linked polyester, the proteins are liberated and visualized on Western blots. The complexes of 1200-1400 kDa molecular mass exceed by far the size of free beta-poly(L-malate) and proteins. The observed variation in mass appears to be mainly a function of the kind and stoichiometry of the protein constituents and may explain the relatively high molecular mass in S phase and the low molecular mass during G2 phase of the mitotic cycle. The complexes are considerably stable at moderate ionic strength (100 mM KCl). Also, endogenous beta-poly(L-malate) does not exchange with added beta-[14C]poly(L-malate) during the lysis of the nuclei and the sample preparation. The complexes are dissociated at elevated concentrations of KCl, in the presence of spermine hydrochloride, or by treatment with DEAE/cellulose. Available evidence indicates that beta-poly(L-malate) may be involved in the maintenance of the plasmodial state of P. polycephalum.
authors.affiliation: Institut für Biophysik und physikalische Biochemie, Universität Regensburg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Angerer
authors.forename: E
authors.initials: E
authors.lastname: Holler
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D002847:Chromatography, Agarose; D003432:Cross-Linking Reagents; D004257:DNA Polymerase II / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005022:Ethyldimethylaminopropyl Carbodiimide; D006609:High Mobility Group Proteins / Q000378:metabolism; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D019811:Hydroxylamine; D006898:Hydroxylamines / Q000494:pharmacology; D008293:Malates / Q000737:chemistry* / Q000378:metabolism; D008938:Mitosis; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D016839:Physarum polycephalum / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011485:Protein Binding; D013096:Spermine / Q000494:pharmacology
chemical_list: D003432:Cross-Linking Reagents; D006609:High Mobility Group Proteins; D006657:Histones; D006898:Hydroxylamines; D008293:Malates; D009687:Nuclear Proteins; D011108:Polymers; D019811:Hydroxylamine; D013096:Spermine; D011189:Potassium Chloride; C074640:poly(malate); D004257:DNA Polymerase II; D005022:Ethyldimethylaminopropyl Carbodiimide