RESUMEN
Fragments of DNA which function as autonomous replication sequences in yeast were cloned from Physarum polycephalum. The ars activity is located in a 1.2 kbp fragment extending 1.5 kbp to 2.7 kbp upstream of the 5' end of a histone H4 gene. Our recent finding that a replication origin is located at a distance less than 3 kbp of this histone gene suggests that the ars element identified coincides with a specialized replication origin and can be used to direct chromosome replication in Physarum polycephalum.
Asunto(s)
Replicación del ADN , Histonas/genética , Physarum/genética , Clonación Molecular , ADN de Hongos/genética , Genes Fúngicos , Ligamiento Genético , Secuencias Reguladoras de Ácidos NucleicosRESUMEN
The histones of Physarum polycephalum have been isolated and fractionated using a combination of gel exclusion and ion-exchange chromatography or differential precipitation. The four core histones were unambiguously identified by gel electrophoresis, amino acid composition and N-terminal analysis. The molecular weight of Physarum histones H3, H2B and H4 are very close or identical to the corresponding histones from chicken erythrocytes. Physarum H2A is significantly larger than chicken erythrocyte H2A and its N-terminal residue is alanine. From the differences in amino acid compositions and in the peptide maps between Physarum and calf H4, one can expected some changes in the amino acid sequence of Physarum H4.