@entity3406 and low CO   -controlled motility in XXXX through complementation of a paralyzed flagella mutant with chemically regulated promoters.

@entity3406 @entity72661 @entity2060 @entity45878 @entity72660
BACKGROUND: @entity2060 is a model system for the biology of unicellular green algae. Chemically regulated promoters, such as the nickel-inducible @entity72660 or the low CO   -inducible @entity72661 promoter, may prove useful for expressing, at precise times during its cell cycle, proteins with relevant biological functions, or complementing mutants in genes encoding such proteins. To this date, this has not been reported for the above promoters. RESULTS: We fused the @entity72660 and @entity72661 promoters to an HA-tagged @entity45878 gene, encoding a protein of the flagellar radial spoke complex. The constructs were used for chemically regulated complementation of the pf14 mutant, carrying an ochre mutation in the @entity45878 gene. 7 to 8% of the transformants showed cells with restored motility after induction with @entity3406 or transfer to low CO    conditions, but not in non-inducing conditions. Maximum complementation (5% motile cells) was reached with very different kinetics (5-6 hours for @entity72661 , 48 hours for @entity72660 ). The two inducible promoters drive much lower levels of @entity45878 protein expression than the constitutive PSAD promoter, which shows almost complete rescue of motility. CONCLUSIONS: To our knowledge, this is the first example of the use of the @entity72660 or @entity72661 promoters to perform a chemically regulated complementation of a @entity2060 mutant. Based on our data, the @entity72660 and @entity72661 promoters should be capable of fully complementing mutants in genes whose products exert their biological activity at low concentrations.
