title: RsmA post-transcriptionally controls PhbR expression and polyhydroxybutyrate biosynthesis in Azotobacter vinelandii.
abstract: In Azotobacter vinelandii the two-component GacS/GacA system is required for synthesis of polyhydroxybutyrate (PHB) and of the exopolysaccharide alginate. The RsmA protein was shown to interact with the alginate biosynthetic algD mRNA, acting as a translational repressor, and GacA was found to activate transcription of the rsmZ1 and rsmZ2 genes that encode small RNAs interacting with RsmA to counteract its repressor activity. The phbBAC operon encodes the enzymes of PHB synthesis and is activated by the transcriptional regulator PhbR. This study shows that GacA is required for transcription of one rsmY and seven rsmZ1-rsmZ7 genes present in the A. vinelandii genome, and that inactivation of rsmA results in increased PHB production. Transcriptional and translational phbR-gusA gene fusions were used to show that the gacA mutation negatively affected the expression of the phbR gene at the translational level. We also demonstrated an in vitro interaction of RsmA with RNAs corresponding to phbB and phbR mRNA leaders, and showed that the stability of phbR and phbB mRNAs is increased in the rsmA mutant. Taken together these results indicate that in A. vinelandii, RsmA post-transcriptionally represses the expression of PhbR.
authors.affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, CP 62210 Cuernavaca, Morelos, México.
authors.forename: Alberto
authors.initials: A
authors.lastname: Hernandez-Eligio
authors.affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, CP 62210 Cuernavaca, Morelos, México.
authors.forename: Soledad
authors.initials: S
authors.lastname: Moreno
authors.affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, CP 62210 Cuernavaca, Morelos, México.
authors.forename: Mildred
authors.initials: M
authors.lastname: Castellanos
authors.affiliation: Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Apartado Postal 1622, CP 72000 Puebla, México.
authors.forename: Miguel
authors.initials: M
authors.lastname: Castañeda
authors.affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, CP 62210 Cuernavaca, Morelos, México.
authors.forename: Cinthia
authors.initials: C
authors.lastname: Nuñez
authors.affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, CP 62210 Cuernavaca, Morelos, México.
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Muriel-Millan
authors.affiliation: Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, CP 62210 Cuernavaca, Morelos, México.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Espín
mesh_terms: D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways; D015964:Gene Expression Regulation, Bacterial; D006885:Hydroxybutyrates / Q000378:metabolism*; D008969:Molecular Sequence Data; D009876:Operon; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D006885:Hydroxybutyrates; D012097:Repressor Proteins