The methanotrophic bacterium Methylosinus trichosporium OB3b converts @entity577 to @entity1042 using two distinct forms of @entity577 monooxygenase (MMO) enzyme: a cytoplasmic soluble form (sMMO) and a membrane-bound form (pMMO). The transcription of these two operons is known to proceed in a reciprocal fashion with sMMO expressed at low @entity920 -to-biomass ratios and pMMO at high @entity920 -to-biomass ratios. Transcription of the smmo operon is initiated from a sigma(N) promoter 5' of mmoX. In this study the genes encoding sigma(N) (rpoN) and a typical sigma(N)-dependent transcriptional activator (mmoR) were cloned and sequenced. mmoR, a regulatory gene, and mmoG, a gene encoding a GroEL homologue, lie 5' of the structural genes for the sMMO enzyme. Subsequent mutation of rpoN and mmoR by marker-exchange mutagenesis resulted in strains Gm1 and @entity69201 , which were unable to express functional sMMO or initiate transcription of mmoX. An rpoN mutant was also unable to fix @entity1568 or use @entity1507 as sole @entity1568 source, indicating that sigma(N) plays a role in both @entity1568 and @entity505 metabolism in Ms. trichosporium OB3b. The data also indicate that mmoG is transcribed in a sigma(N)- and MmoR-independent manner. Marker-exchange mutagenesis of mmoG revealed that MmoG is necessary for smmo gene transcription and activity and may be an MmoR-specific chaperone required for functional assembly of transcriptionally competent MmoR in vivo. The data presented allow the proposal of a more complete model for @entity920 -mediated regulation of smmo gene expression.

rpoN, mmoR and mmoG, genes involved in regulating the expression of soluble XXXX monooxygenase in Methylosinus trichosporium OB3b.

@entity1568 :: ('MESH:D009584', 'Chemical') :: ['nitrogen'] @entity1042 :: ('MESH:D000432', 'Chemical') :: ['methanol'] @entity69201 :: ('134147', 'Gene') :: ['JS1'] @entity1507 :: ('CHEBI:48107', 'Chemical') :: ['nitrate'] @entity577 :: ('MESH:D008697', 'Chemical') :: ['methane'] @entity920 :: ('MESH:D003300', 'Chemical') :: ['copper'] @entity505 :: ('MESH:D002244', 'Chemical') :: ['carbon']
@entity577 :: (MESH:D008697,Chemical) :: ['methane']
