Dark-induced mRNA instability involves RNase E/G-type endoribonuclease cleavage at the AU-box and SD sequences in cyanobacteria.
Light-responsive gene expression is crucial to photosynthesizing organisms. Here, we studied functions of cis-elements (AU-box and SD sequences) and a trans-acting factor (ribonuclease, RNase) in light-responsive expression in cyanobacteria. The results indicated that AU-rich nucleotides with an AU-box, UAAAUAAA, just upstream from an SD confer instability on the mRNA under darkness. An RNase E/G homologue, Slr1129, of the cyanobacterium Synechocystis sp. strain PCC 6803 was purified and confirmed capable of endoribonucleolytic cleavage at the AU- (or AG)-rich sequences in vitro. The cleavage depends on the primary target sequence and secondary structure of the mRNA. Complementation tests using Escherichia coli rne/rng mutants showed that Slr1129 fulfilled the functions of both the RNase E and RNase G. An analysis of systematic mutations in the AU-box and SD sequences showed that the cis-elements also affect significantly mRNA stability in light-responsive genes. These results strongly suggested that dark-induced mRNA instability involves RNase E/G-type cleavage at the AU-box and SD sequences in cyanobacteria. The mechanical impact and a possible common mechanism with RNases for light-responsive gene expression are discussed.
Laboratory of Molecular Genetics, School of Agriculture, Ibaraki University, Ami, Inashiki, Ibaraki 300-0393, Japan.
Yoshinao
Y
Horie
Yoko
Y
Ito
Miyuki
M
Ono
Naoko
N
Moriwaki
Hideki
H
Kato
Yuriko
Y
Hamakubo
Tomoki
T
Amano
Masaaki
M
Wachi
Makoto
M
Shirai
Munehiko
M
Asayama
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003624:Darkness; D004722:Endoribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D020871:RNA Stability; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D046939:Synechocystis / Q000235:genetics* / Q000378:metabolism*
D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011994:Recombinant Proteins; C422369:photosystem II, psbA subunit; D004722:Endoribonucleases; C022537:ribonuclease E