Abstract
The green alga Chlamydomonas reinhardtii contains nine distinct light-harvesting complexes I (Lhca1-9) that are tightly associated with photosystem I core complex. Using a battery of antibodies raised against nine Lhca polypeptides, we analyzed the amounts of the nine Lhca polypeptides as well as photosystem I polypeptides in two Chlamydomonas mutants; BF4 deficient in light-harvesting complexes and delta-Chlb deficient in synthesis of chlorophyll b. BF4 lacked most Lhca polypeptides except Lhca5 and Lhca6 at low levels. Chlb-deficient mutant accumulated only a small amount of Lhca2 when grown in dim light but accumulated Lhca9 at normal level when grown in bright light. Of interest is that dim light-grown BF4 and Chlb-deficient mutants lacked photosystem I subunits located at close proximity of oligomeric structure of Lhca complexes, indicating that their accumulation is stabilized by the presence of Lhca complexes. Taken together, a possible structure of Lhca complexes in photosystem I will be discussed.
