Regulation of Expression of Genes Involved in Quinate and Shikimate Utilization in Corynebacterium glutamicum

Abstract

The utilization of the hydroaromatic compounds quinate and shikimate by Corynebacterium glutamicum was investigated. C. glutamicum grew well with either quinate or shikimate as the sole carbon source. The disruption of qsuD, encoding quinate/shikimate dehydrogenase, completely suppressed growth with either substrate but did not affect growth with glucose, indicating that the enzyme encoded by qsuD catalyzes the first step of the catabolism of quinate/shikimate but is not involved in the shikimate pathway required for the biosynthesis of various aromatic compounds. On the chromosome of C. glutamicum, the qsuD gene is located in a gene cluster also containing qsuA, qsuB, and qsuC genes, which are probably involved in the quinate/shikimate utilization pathway to form protocatechuate. Reverse transcriptase PCR analyses revealed that the expression of the qsuABCD genes was markedly induced during growth with either quinate or shikimate relative to expression during growth with glucose. The induction level by shikimate was significantly decreased by the disruption of qsuR, which is located immediately upstream of qsuA in the opposite direction and encodes a LysR-type transcriptional regulator, suggesting that QsuR acts as an activator of the qsuABCD genes. The high level of induction of qsuABCD genes by shikimate was still observed in the presence of glucose, and simultaneous consumption of glucose and shikimate during growth was observed.The abundant plant products quinate and shikimate are utilized as carbon and/or energy sources by various microorganisms. The quinate utilization pathways in the filamentous fungi Neurospora crassa and Aspergillus nidulans have been well studied ( Fig. 1) (12, 14). Quinate is converted to protocatechuate via three enzymatic reactions, catalyzed by quinate dehydrogenase, dehydroquinate dehydratase, and dehydroshikimate dehydratase. Subsequently, protocatechuate is metabolized through the ␤-ketoadipate pathway. The expression of these enzymes is induced during growth on quinate and is subject to carbon catabolite repression (12)(13)(14). The first enzyme for the utilization of quinate, quinate dehydrogenase, also converts shikimate to dehydroshikimate. Dehydroquinate and dehydroshikimate are also intermediates of the shikimate pathway, leading to branched pathways of biosynthesis of various aromatic amino acids, vitamins, and quinones. The biosynthetic reactions of dehydroquinate dehydratase and shikimate dehydrogenase are the same as the quinate/shikimate catabolic reactions. However, separately from the inducible catabolic enzymes, a constitutive pentafunctional enzyme containing the dehydroquinate dehydratase and shikimate dehydrogenase activities is involved in the shikimate biosynthetic pathway (12,14). The pentafunctional enzyme contains regions with amino acid sequence similarity to five shikimate pathway enzymes encoded by separate genes in bacteria, implying multiple gene fusion during evolution.Among gram-negative bacteria, Acinetobacter species utilize quinate and shikimate ...

The LacI-Type Transcriptional Regulator AraR Acts as an l -Arabinose-Responsive Repressor of l -Arabinose Utilization Genes in Corynebacterium glutamicum ATCC 31831

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Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

“…Besides, no HPr kinase/phosphatase system is found in the C. glutamicum genome. These differences in the molecular characteristics are likely reflected in the capacity of C. glutamicum to cometabolize glucose and a variety of carbon sources, including sugars, organic acids, and aromatic compounds without catabolite repression (17)(18)(19)(20)(21)(22)(23)(24), expect for a few cases (25)(26)(27).…”

Molecular characterization of a eukaryotic-like phenol hydroxylase from <i>Corynebacterium glutamicum</i>

“…Similar phenomenon was reported for QsuD (quinate/shikimate dehydrogenase), QsuC (dehyroquinate dehydratase), and QsuB (dehyroshikimate dehydratase), the three proteins involved in quinate metabolism in C. glutamicum. QsuD, QsuC and QsuB are not homologous to their counterparts such as QuiA, QuiB, and QuiC in bacteria, instead, they can be classified into the families of fungal enzymes QutB, QutE, and QutC (Teramoto et al, 2009).…”