Title

Mutational analysis of the phototransduction pathway of Chlamydomonas reinhardtii

UMMS Affiliation

Department of Cell Biology; Program in Molecular Medicine

Date

10-1-1995

Document Type

Article

Subjects

Animals; Chlamydomonas reinhardtii; DNA; DNA Mutational Analysis; Electrophysiology; Light; Mutagenesis, Insertional; Rhodopsin; *Signal Transduction

Abstract

Chlamydomonas has two photobehavioral responses, phototaxis and photoshock. Rhodopsin is the photoreceptor for these responses and the signal transduction process involves transmembrane Ca2+ fluxes. This causes transient changes in flagellar beating, ultimately resulting in phototaxis or photoshock. To identify components that make up this signal transduction pathway, we generated nonphototactic strains by insertional mutagenesis. Seven new phototaxis genes were identified (ptx2-ptx8); alleles of six of these are tagged by the transforming DNA and therefore should be easily cloned. To order the mutants in the pathway, we characterized them electrophysiologically, behaviorally, and structurally, ptx5, ptx6, and ptx7 have normal light-induced photoreceptor currents (PRC) and flagellar currents (FC) but their pattern of swimming does not change in the normal manner when the intraflagellar Ca2+ concentration is decreased, suggesting that they have defects in the ability of their axonemes to respond to changes in Ca2+ concentration. ptx2 and ptx8 lack the FC but have normal PRCs, suggesting that they are defective in the flagellar Ca2+ channel or some factor that regulates it. ptx4 mutants have multiple eye-spots. ptx3 mutants are defective in a component essential for phototaxis but bypassed during photoshock; this component appears to be located downstream of the PRC but upstream of the axoneme.

Rights and Permissions

Citation: J Cell Biol. 1995 Oct;131(2):427-40.

Related Resources

Link to Article in PubMed

Journal Title

The Journal of cell biology

PubMed ID

7593169