Site-directed mutagenesis study of a novel drosophila circadian protein

Abstract

A wide variety of organisms display circadian rhythms ranging from daily fluctuations in cellular biochemistry and physiology to complex behaviors. These rhythms are governed by endogenous biological oscillators that can be entrained by environmental stimuli, most notably the daily light-dark cycles. This adaptive feature of circadian oscillators enables organisms to maintain temporal alignment between their endogenously driven rhythms and the solar day. The circadian timing system is generally considered to consist of three interconnected parts: (ⅰ) input pathways that can receive and transmit external time cues to the clock, (ⅱ) the timekeeping mechanism itself, and (ⅲ) downstream effector pathways that are temporally regulated by the clock. Here, circadian GPCR gene, han belongs to the family-B GPCRs. Specific change by mutagenesis of a strictly conserved histidine into arginine at position 276 of han resulted in its constitutive activation with respect to cAMP production. The H276R mutant did not involve in PER repression activity on CLK/CYC transcriptional activity.