Exploring the role of sigma factor gene expression on production by XXXX : sigma factor H and @entity10698 as example.

@entity9150 @entity6874 @entity10698 @entity1110 @entity36435 @entity10697 @entity8728
Bacteria are known to cope with environmental changes by using alternative sigma factors binding to RNA polymerase core enzyme. Sigma factor is one of the targets to modify transcription regulation in bacteria and to influence production capacities. In this study, the effect of overexpressing each annotated sigma factor gene in @entity9150 WT was assayed using an @entity6874 inducible plasmid system and different @entity6874 concentrations. It was revealed that growth was severely decreased when sigD or sigH were overexpressed with @entity6874 concentrations higher than 50  M. Overexpression of sigH led to an obvious phenotypic change, a yellow-colored supernatant. High performance liquid chromatography analysis revealed that @entity8728 was excreted to the medium when sigH was overexpressed and DNA microarray analysis confirmed increased expression of @entity8728 biosynthesis genes. In addition, genes for enzymes related to the @entity36435 pathway and for enzymes dependent on @entity10698 ( @entity10698 ), @entity10697 ( @entity10697 ), or @entity1110 as cofactor were upregulated when sigH was overexpressed. To test if sigH overexpression can be exploited for production of @entity8728 -derived @entity10698 or @entity10697 , the endogenous gene for bifunctional @entity8728 kinase/ @entity10698 adenyltransferase was co-expressed with sigH from a plasmid. Balanced expression of sigH and ribF improved accumulation of @entity8728 (19.8    0.3  M) and allowed for its conversion to @entity10698 (33.1    1.8  M) in the supernatant. While a proof-of-concept was reached, conversion was not complete and titers were not high. This study revealed that inducible and gradable overexpression of sigma factor genes is an interesting approach to switch gene expression profiles and to discover untapped potential of bacteria for chemical production.
