Identification of target mRNAs for the clock-controlled RNA-binding protein Chlamy 1 from Chlamydomonas reinhardtii.
An endogenous clock regulates the temporal expression of genes/mRNAs that are involved in the circadian output pathway. In the green alga Chlamydomonas reinhardtii, a clock-controlled RNA-binding protein (Chlamy 1) was identified recently, which represents an analog of the circadian trans-acting factor CCTR from the phylogenetically diverse alga Gonyaulax polyedra. In order to identify in C. reinhardtii target mRNAs that can be recognized by Chlamy 1, gel mobility-shift assays and UV-crosslinking experiments were carried out, and revealed that this protein interacts specifically with the 3' untranslated regions of several mRNAs and recognizes them all via a common cis-acting element, composed of at least seven UG repeats. By using competition assays, it was found that the affinity of Chlamy 1 is highest for mRNAs whose products are key components of nitrogen and CO2 metabolism. Since the activities of enzymes involved in nitrogen metabolism vary in a temporal pattern that is opposite in phase to that of Chlamy 1 binding activity, the protein may repress the translation of the cognate mRNAs.
Waltenberger
H
H
Botanisches Institut, Ludwig-Maximilians-Universität München, Germany.
Schneid
C
C
Grosch
J O
JO
Bareiss
A
A
Mittag
M
M
D020413:3' Untranslated Regions; D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid
D020413:3' Untranslated Regions; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D002245:Carbon Dioxide; D009584:Nitrogen