English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The aconitase gene acn of Corynebacterium glutamicum is regulated by four transcriptional regulators, indicating that the synthesis of this enzyme is carefully controlled. To understand the causes for this elaborate regulation, the properties of the Δacn-1 deletion mutant were analyzed in detail. The mutant was glutamate auxotrophic in glucose minimal medium, showed a strong growth defect, and secreted large amounts of acetate. None of these phenotypes could be complemented by plasmid-encoded aconitase, suggesting the presence of a secondary mutation. In fact, a point mutation within the gltA gene encoding citrate synthase was identified that caused the instability of the protein and an almost complete lack of its enzymatic activity. Subsequently, 27 further, independent Δacn clones were isolated, and 15 of them were found to contain distinct mutations in gltA, causing the loss of citrate synthase activity. A similar result was observed for mutants lacking the isocitrate dehydrogenase gene icd. In this case, 8 of 24 Δicd clones contained additional mutations in gltA. Indirect evidence was obtained that elevated intracellular citrate concentrations could be the cause of this selection pressure. Accordingly, the careful control of aconitase synthesis might have evolved due to the necessity to avoid inhibitory cytoplasmic citrate levels on the one hand and to prevent the excessive synthesis of an oxygen-sensitive protein requiring both iron and sulfur on the other hand.

Deletion of the Aconitase Gene in Corynebacterium glutamicum Causes Strong Selection Pressure for Secondary Mutations Inactivating Citrate Synthase