Subategory:

Mutants

Description:

Using standard methods of directed mutagenesis and chloroplast transformation of rbcLΔ-MX3312 mt+ (MUT-4696), four substitutions (V221C, C256F, K258R, and I265V) together in the Rubisco large subunit were created. This mutant (also named AG221) represents one of 15 "associated groups" of amino acids that differ between Chlamydomonas and land plants. It was created to investigate phylogenetic differences that influence Rubisco catalysis. The mutant enzyme has a decrease in CO₂/O₂ specificity. The mutant strain can grow on minimal medium at 25 °C, but dies on minimal medium at 35 °C, and has a decreased amount of Rubisco holoenzyme when grown at 35 °C with acetate medium in darkness. This strain has been maintained with acetate medium in darkness to prevent selection for secondary mutations that may improve Rubisco function.

Species:

Chlamydomonas

Locus:

rbcL

Chromosome:

Chloroplast

Phenotype:

Requires acetate at 35 °C; temperature-conditional