Subategory:

Mutants

Description:

Directed mutagenesis and chloroplast transformation of rbcLΔ-25B1 mt+ (MUT-4700) were used to create L326I (CTT-ATT) and M349L (ATG-CTG) substitutions in the Rubisco large subunit, which complemented for structural stability but decreased CO₂/O₂ specificity. The L326I/M349L double mutant was created to investigate phylogenetic differences near large-subunit residue Val-331 (see rbcL-V331A). After being maintained with acetate medium in darkness for several years, the original L326I/M349L double-mutant culture was found to contain only two types of mutant cells, both of which had additional mutations in the rbcL gene. L326I/V341I/M349L/A378T mutant cells had an acetate-requiring phenotype, and H310N/L326I/M349L cells had a wild-type phenotype. It was proposed that these additional substitutions may have been selected because they improve Rubisco holoenzyme stability. See also MUT-4713 and MUT-4714. It has been maintained with acetate medium in darkness since it was created, but it has not been investigated for the presence of suppressor mutations.

Species:

Chlamydomonas

Locus:

rbcL

Chromosome:

Chloroplast