Molecular characterization of the Rpt1/p48B ATPase subunit of the Drosophila melanogaster 26S proteasome.
The function and the molecular properties of the Rpt1/p48B ATPase subunit of the regulatory particle of the Drosophila melanogaster 26S proteasome have been studied by analyzing three mutant Drosophila stocks in which P-element insertions occurred in the 5'-non-translated region of the Rpt1/p48B gene. These P-element insertions resulted in larval lethality during the second instar larval phase. Since the Rpt1/p48B gene resides within a long intron of an annotated, but uncharacterized Drosophila gene (CG17985), the second instar larval lethality may be a consequence of a combined damage to two independent genes. To analyze the phenotypic effect of the mutations affecting the Rpt1/p48B gene alone, imprecise P-element excision mutants were selected. One of them, the pupal lethal P1 mutation, is a hypomorphic allele of the Rpt1/p48B gene, in which the displacement of two essential regulatory sequences of the gene occurred due to the insertion of a 32 bp residual P-element sequence. This mutation caused a 30-fold drop in the cellular concentration of the Rpt1/p48B mRNA. The decline in the cellular Rpt1/p48B protein concentration induced serious damage in the assembly of the 26S proteasomes, the accumulation of multiubiquitinated proteins, a change in the phosphorylation pattern of the subunit and depletion of this ATPase protein from the chromatin.
Szabó
Aron
A
Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, P.O.Box 521, 6701, Szeged, Hungary, udvardy@brc.hu.
Pál
Margit
M
Deák
Péter
P
Kiss
Petra
P
Ujfaludi
Zsuzsa
Z
Pankotai
Tibor
T
Lipinszki
Zoltán
Z
Udvardy
Andor
A
D000483:Alleles; D000818:Animals; D001483:Base Sequence; D002843:Chromatin / Q000378:metabolism; D002875:Chromosomes / Q000648:ultrastructure; D004331:Drosophila melanogaster / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000235:genetics* / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism
D002843:Chromatin; D012333:RNA, Messenger; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease