cDNA clones encoding Arabidopsis thaliana and Zea mays mitochondrial chaperonin HSP60 and gene expression during seed germination and heat shock.
Mitochondria contain a nuclear-encoded heat shock protein, HSP60, which functions as a chaperonin in the post-translational assembly of multimeric proteins encoded by both nuclear and mitochondrial genes. We have isolated and sequenced full-length complementary DNAs coding for this mitochondrial chaperonin in Arabidopsis thaliana and Zea mays. Southern-blot analysis indicates the presence of a single hsp60 gene in the genome of A. thaliana. There is a high degree of homology at the predicted amino acid levels (43 to 60%) between plant HSP60s and their homologues in prokaryotes and other eukaryotes which indicates that these proteins must have similar evolutionarily conserved functions in all organisms. Northern- and western-blot analyses indicate that the expression of the hsp60 gene is developmentally regulated during seed germination. It is also heat-inducible. Developmental regulation of the (beta-subunit of F1-ATPase, an enzyme complex that is involved in the cyanide-sensitive mitochondrial electron transport system, indicates that imbibed embryos undergo rapid mitochondrial biogenesis through the early stages of germination. Based on the functional role of HSP60 in macromolecular assembly, these data collectively suggest that the presence of higher levels of HSP60 is necessary during active mitochondrial biogenesis, when the need for this protein is greatest in assisting the rapid assembly of the oligomeric protein structures.
Prasad
T K
TK
Department of Botany, Iowa State University, Ames 50011.
Stewart
C R
CR
D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D018834:Chaperonin 60; D003001:Cloning, Molecular; D005786:Gene Expression Regulation / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics*; D006358:Hot Temperature; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics; D063245:Plant Development; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D010944:Plants / Q000196:embryology / Q000235:genetics*; D006180:Proton-Translocating ATPases / Q000235:genetics*; D012639:Seeds / Q000235:genetics / Q000254:growth & development; D012689:Sequence Homology, Nucleic Acid; D003313:Zea mays / Q000196:embryology / Q000235:genetics / Q000254:growth & development
D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D006180:Proton-Translocating ATPases