Different period gene repeats take 'turns' at fine-tuning the circadian clock.
The repetitive region of the circadian clock gene period in Drosophila pseudoobscura consists predominantly of a pentapeptide sequence whose consensus is NSGAD. In D. melanogaster, this region is replaced by a dipeptide Thr-Gly repeat, which plays a role in the thermal stability of the circadian phenotype. The Thr-Gly repeat has been shown to form a type II or III beta-turn, whose conformational monomer is (Thr-Gly)3. Here we report, using conformational analyses, that both an NSGAD pentapeptide, and a polymer of the same sequence, form type II beta-turns. Thus two peptide sequences, whose amino-acid composition is very different, nevertheless form the same secondary structure. The implications of these structures for clock function are discussed.
Guantieri
V
V
Department of Inorganic Chemistry, Università di Padova, Italy.
Pepe
A
A
Zordan
M
M
Kyriacou
C P
CP
Costa
R
R
Tamburro
A M
AM
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm / Q000235:genetics*; D002942:Circular Dichroism; D004151:Dipeptides / Q000737:chemistry / Q000235:genetics; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D017344:Genes, Insect / Q000235:genetics; D005998:Glycine / Q000235:genetics; D019476:Insect Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D013696:Temperature; D013912:Threonine / Q000235:genetics
D004151:Dipeptides; D019476:Insect Proteins; D013912:Threonine; D005998:Glycine