Biogenesis of photosystem II complexes: transcriptional, translational, and posttranslational regulation

Journal Article · Wed Oct 01 04:00:00 EDT 1986 · J. Cell Biol.; (United States)

DOI:https://doi.org/10.1083/jcb.103.4.1315· OSTI ID:6592306

Jensen, K H; Herrin, D L; Plumley, F G; Schmidt, G W

The integral membrane proteins of photosystem II (PS II) reaction center complexes are encoded by chloroplast genomes. These proteins are absent from thylakoids of PS II mutants of algae and vascular plants as a result of either chloroplast or nuclear gene mutations. To resolve the molecular basis and the concurrent absence of the PS II polypeptides, protein synthesis rates and mRNA levels were measured in mutants of Chlamydomonas reinhardtii that lack PS II. The analyses show that one nuclear gene product regulates the levels of transcripts from the chloroplast gene encoding the 51-kD chlorophyll ..cap alpha..-binding polypeptide (polypeptide 5) but is not involved in the synthesis of other chloroplast mRNAs. The other nuclear product is specifically required for translation of mRNA encoding the 32-34-kD polypeptide, D1. The absence of either D1 or polypeptide 5 does not eliminate the synthesis and thylakoid insertion of two other integral membrane proteins of PS II, the chlorophyll ..cap alpha..-binding polypeptide of 46 kD (polypeptide 6) and the 30-kD D1-like protein, D2. However, these two unassembled subunits cannot be properly processed and/or are degraded in the mutants even though they reside in the membrane. In addition, pulse labeling of the nuclear mutants and a chloroplast mutant that does not synthesize D1 mRNA indicates that synthesis of polypeptide 5 and D1 is coordinated at the translational level. A model is presented to explain how absence of one of the two proteins could lead to translational arrest of the other.

• Research Organization: Univ. of Georgia, Athens
• DOE Contract Number: FG09-84ER13188
• OSTI ID: 6592306
• Journal Information: J. Cell Biol.; (United States), Journal Name: J. Cell Biol.; (United States) Vol. 103:4; ISSN JCLBA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALGAE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOSYNTHESIS
CELL CONSTITUENTS
CHLAMYDOMONAS
CHLOROPLASTS
DAYS LIVING RADIOISOTOPES
EVEN-ODD NUCLEI
GENES
ISOTOPES
LIGHT NUCLEI
MESSENGER-RNA
MICROORGANISMS
MOLECULAR BIOLOGY
MUTANTS
NUCLEI
NUCLEIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOTOSYNTHETIC REACTION CENTERS
PLANTS
PROTEINS
RADIOISOTOPES
RNA
SULFATES
SULFUR 35
SULFUR COMPOUNDS
SULFUR ISOTOPES
SYNTHESIS
TRANSCRIPTION
UNICELLULAR ALGAE