Nonsense mutations in the Chlamydomonas chloroplast gene that codes for the large subunit of ribulosebisphosphate carboxylase/oxygenase
AUTOR(ES)
Spreitzer, Robert J.
RESUMO
The Chlamydomonas reinhardtii chloroplast mutants 18-5B and 18-7G lack both the chloroplast-encoded large subunit and nuclear-encoded small subunit of the chloroplast enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39). A chloroplast intergenic-suppression model has been postulated to account for the genetic instability of 18-5B revertants. Here, we have determined the molecular basis of the 18-5B and 18-7G mutants. They contain nonsense mutations close to the 3′ and 5′ ends of their large-subunit genes, respectively. Pulse-chase experiments revealed that the 18-5B mutant produces a truncated large subunit that is unstable. In connection with previous experiments, this work identifies nonsense suppression in the chloroplast. Small subunits are also synthesized but then degraded in the mutants. Thus, the coordinated absence of subunits is achieved through degradation of the small subunit in the specific absence of the large subunit.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=390589Documentos Relacionados
- Rapid recovery of chloroplast mutations affecting ribulosebisphosphate carboxylase/oxygenase in Chlamydomonas reinhardtii
- Reduced CO2/O2 specificity of ribulose-bisphosphate carboxylase/oxygenase in a temperature-sensitive chloroplast mutant of Chlamydomonas.
- Elimination of the Chlamydomonas gene family that encodes the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase
- Pseudoreversion substitution at large-subunit residue 54 influences the CO2/O2 specificity of chloroplast ribulose-bisphosphate carboxylase/oxygenase.
- Activation of Ribulosebisphosphate Carboxylase/Oxygenase at Physiological CO2 and Ribulosebisphosphate Concentrations by Rubisco Activase
