Isolation and partial characterization of the Chlamydomonas reinhardtii γ-glutamyl kinase

We isolated a Chlamydomonas gene encoding putative γ-glutamyl kinase (GK), an enzyme that catalyzes the first step of proline biosynthesis. Using an Escherichia coli auxotroph and a purified recombinant protein, we show that Chlamydomonas GK is a functional GK. The sensitivity of this kinase to feedback inhibition by proline was lower than in that of microbial GKs previously reported.