Large complexes of beta-poly(L-malate) with DNA polymerase alpha, histones, and other proteins in nuclei of growing plasmodia of Physarum polycephalum

Biochemistry. 1995 Nov 14;34(45):14741-51. doi: 10.1021/bi00045a015.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle
  • Cell Nucleus / chemistry
  • Cell Nucleus / metabolism
  • Chromatography, Agarose
  • Cross-Linking Reagents
  • DNA Polymerase II / antagonists & inhibitors
  • DNA Polymerase II / chemistry
  • DNA Polymerase II / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • Ethyldimethylaminopropyl Carbodiimide
  • High Mobility Group Proteins / metabolism
  • Histones / chemistry
  • Histones / metabolism*
  • Hydroxylamine
  • Hydroxylamines / pharmacology
  • Malates / chemistry*
  • Malates / metabolism
  • Mitosis
  • Molecular Weight
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / metabolism*
  • Physarum polycephalum / chemistry*
  • Polymers / chemistry*
  • Polymers / metabolism
  • Potassium Chloride / pharmacology
  • Protein Binding
  • Spermine / pharmacology


  • Cross-Linking Reagents
  • High Mobility Group Proteins
  • Histones
  • Hydroxylamines
  • Malates
  • Nuclear Proteins
  • Polymers
  • Hydroxylamine
  • Spermine
  • Potassium Chloride
  • poly(malate)
  • DNA Polymerase II
  • Ethyldimethylaminopropyl Carbodiimide