The RNA molecule CsrB binds to the global regulatory protein CsrA and antagonizes its activity in Escherichia coli.
The RNA-binding protein CsrA (carbon storage regulator) is a new kind of global regulator, which facilitates specific mRNA decay. A recombinant CsrA protein containing a metal-binding affinity tag (CsrA-H6) was purified to homogeneity and authenticated by N-terminal sequencing, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and other studies. This protein was entirely contained within a globular complex of approximately 18 CsrA-H6 subunits and a single approximately 350-nucleotide RNA, CsrB. cDNA cloning and nucleotide sequencing revealed that the csrB gene is located downstream from syd in the 64-min region of the Escherichia coli K-12 genome and contains no open reading frames. The purified CsrA-CsrB ribonucleoprotein complex was active in regulating glg (glycogen biosynthesis) gene expression in vitro, as was the RNA-free form of the CsrA protein. Overexpression of csrB enhanced glycogen accumulation in E. coli, a stationary phase process that is repressed by CsrA. Thus, CsrB RNA is a second component of the Csr system, which binds to CsrA and antagonizes its effects on gene expression. A model for regulatory interactions in Csr is presented, which also explains previous observations on the homologous system in Erwinia carotovora. A highly repeated nucleotide sequence located within predicted stem-loops and other single-stranded regions of CsrB, CAGGA(U/A/C)G, is a plausible CsrA-binding element.
Liu
M Y
MY
Department of Microbiology and Immunology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas 76107-2699, USA.
Gui
G
G
Wei
B
B
Preston
J F
JF
Oakford
L
L
Yüksel
U
U
Giedroc
D P
DP
Romeo
T
T
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D006193:Haemophilus influenzae; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016973:Pectobacterium carotovorum; D012313:RNA / Q000378:metabolism*; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D001426:Bacterial Proteins; C093587:CsrA protein, E coli; C107123:CsrB RNA, E coli; D029968:Escherichia coli Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; C095468:RsmA protein, Erwinia carotovora; D012313:RNA