N. meningitidis 1681 is a member of the FinO family of RNA chaperones.
The conjugative transfer of F-like plasmids between bacteria is regulated by the plasmid-encoded RNA chaperone, FinO, which facilitates sense - antisense RNA interactions to regulate plasmid gene expression. FinO was thought to adopt a unique structure, however many putative homologs have been identified in microbial genomes and are considered members of the FinO_conjugation_repressor superfamily. We were interested in determining whether other members were also able to bind RNA and promote duplex formation, suggesting that this motif does indeed identify a putative RNA chaperone. We determined the crystal structure of the N. meningitidis MC58 protein NMB1681. It revealed striking similarity to FinO, with a conserved fold and a large, positively charged surface that could function in RNA interactions. Using assays developed to study FinO-FinP sRNA interactions, NMB1681, like FinO, bound tightly to FinP RNA stem-loops with short 5' and 3' single-stranded tails but not to ssRNA. It also was able to catalyze strand exchange between an RNA duplex and a complementary single-strand, and facilitated duplexing between complementary RNA hairpins. Finally, NMB1681 was able to rescue a finO deficiency and repress F plasmid conjugation. This study strongly suggests that NMB1681 is a FinO-like RNA chaperone that likely regulates gene expression through RNA-based mechanisms in N. meningitidis.
Department of Biochemistry, University of Alberta, Edmonton, Canada.
Steven
S
Chaulk
Jun
J
Lu
Kemin
K
Tan
David C
DC
Arthur
Ross A
RA
Edwards
Laura S
LS
Frost
Andrzej
A
Joachimiak
J N Mark
JN
Glover
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003227:Conjugation, Genetic; D005144:F Factor / Q000378:metabolism; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000235:genetics* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D001426:Bacterial Proteins; D018832:Molecular Chaperones; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012313:RNA