In the filamentous, heterocyst-forming cyanobacterium @entity13931 , the glnB gene is expressed at considerable levels both in the presence and in the absence of combined @entity1568 , although induction, influenced by NtcA, takes place upon combined- @entity1568 deprivation likely localized to vegetative cells. In spite of extensive efforts, a derivative of @entity13931 lacking a functional glnB gene could be obtained only with constructs that lead to overexpression of a downstream @entity5545 ( @entity5545 ), particularly all2318. Strain CSP10 [glnB all2318(Con)] exhibited growth rates similar to those of the wild type when it was using @entity1507 or @entity3104 , but its diazotrophic growth was impaired. However, it differentiated heterocysts with a time course and distribution pattern similar to those of the wild type, although with no @entity14780 -containing polar granules, and exhibited impaired nitrogenase activity under oxic conditions, but not under microoxic conditions. In the mutant, NtcA-dependent induction of the hetC and nifH genes was unaltered, but induction of the urtA gene and @entity1133 transport activity were increased. Active uptake of @entity3542 was also increased and insensitive to the @entity3104 -promoted inhibition observed for the wild type. Thus, regulation of the @entity3542 transport activity requires the glnB gene product. In the presence of a wild-type glnB gene, neither inactivation nor overexpression of all2318 produced an apparent phenotype. Thus, in an otherwise wild-type background, the glnB gene appears to be essential for growth of strain @entity13931 . For growth with combined @entity1568 but not for diazotrophic growth, the requirement for glnB can be overridden by increasing the expression of all2318 (and/or ORFs downstream of it).

Expression and mutational analysis of the glnB genomic region in the heterocyst-forming Cyanobacterium XXXX .

@entity1568 :: ('MESH:D009584', 'Chemical') :: ['nitrogen'] @entity1133 :: ('MESH:D014508', 'Chemical') :: ['urea'] @entity3542 :: ('CHEBI:16301', 'Chemical') :: ['nitrite'] @entity1507 :: ('CHEBI:48107', 'Chemical') :: ['nitrate'] @entity13931 :: ('103690', 'Species') :: ['Anabaena sp. strain PCC 7120', 'PCC 7120'] @entity14780 :: ('CHEBI:65319', 'Chemical') :: ['cyanophycin'] @entity3104 :: ('MESH:D000644', 'Chemical') :: ['ammonium'] @entity5545 :: ('MESH:D004410', 'Disease') :: ['open reading frames', 'ORF']
@entity13931 :: (103690,Species) :: ['Anabaena sp. strain PCC 7120']
