Structural and functional studies of RegB, a new member of a family of sequence-specific ribonucleases involved in mRNA inactivation on the ribosome.
The RegB endoribonuclease participates in the bacteriophage T4 life cycle by favoring early messenger RNA breakdown. RegB specifically cleaves GGAG sequences found in intergenic regions, mainly in translation initiation sites. Its activity is very low but can be enhanced up to 100-fold by the ribosomal 30 S subunit or by ribosomal protein S1. RegB has no significant sequence homology to any known protein. Here we used NMR to solve the structure of RegB and map its interactions with two RNA substrates. We also generated a collection of mutants affected in RegB function. Our results show that, despite the absence of any sequence homology, RegB has structural similarities with two Escherichia coli ribonucleases involved in mRNA inactivation on translating ribosomes: YoeB and RelE. Although these ribonucleases have different catalytic sites, we propose that RegB is a new member of the RelE/YoeB structural and functional family of ribonucleases specialized in mRNA inactivation within the ribosome.
Odaert
Benoît
B
ICSN-RMN, Institut de Chimie des Substances Naturelles, CNRS de Gif-sur-Yvette, 91190 Gif-sur-Yvette et Ecole Polytechnique, 91128 Palaiseau, France.
Saïda
Fakhri
F
Aliprandi
Pascale
P
Durand
Sylvain
S
Créchet
Jean-Bernard
JB
Guerois
Raphaël
R
Laalami
Soumaya
S
Uzan
Marc
M
Bontems
François
F
D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000378:metabolism; D017122:Bacteriophage T4 / Q000378:metabolism*; D020134:Catalytic Domain; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D014176:Protein Biosynthesis; D011487:Protein Conformation; D012333:RNA, Messenger / Q000378:metabolism; D012260:Ribonucleases / Q000096:biosynthesis / Q000737:chemistry*; D012270:Ribosomes / Q000378:metabolism
D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D012333:RNA, Messenger; C465566:RelE protein, E coli; C504245:YoeB protein, E coli; D012260:Ribonucleases