Glucosamine as carbon source for amino acid-producing Corynebacterium glutamicum

Abstract

Corynebacterium glutamicum grows with a variety of carbohydrates and carbohydrate derivatives as sole carbon sources; however, growth with glucosamine has not yet been reported. We isolated a spontaneous mutant (M4) which is able to grow as fast with glucosamine as with glucose as sole carbon source. Glucosamine also served as a combined source of carbon, energy and nitrogen for the mutant strain. Characterisation of the M4 mutant revealed a significantly increased expression of the nagB gene encoding the glucosamine-6P deaminase NagB involved in degradation of glucosamine, as a consequence of a single mutation in the promoter region of the nagAB-scrB operon. Ectopic nagB overexpression verified that the activity of the NagB enzyme is in fact the growth limiting factor under these conditions. In addition, glucosamine uptake was studied, which proved to be unchanged in the wild-type and M4 mutant strains. Using specific deletion strains, we identified the PTS(Glc) transport system to be responsible for glucosamine uptake in C. glutamicum. The affinity of this uptake system for glucosamine was about 40-fold lower than that for its major substrate glucose. Because of this difference in affinity, glucosamine is efficiently taken up only if external glucose is absent or present at low concentrations. C. glutamicum was also examined for its suitability to use glucosamine as substrate for biotechnological purposes. Upon overexpression of the nagB gene in suitable C. glutamicum producer strains, efficient production of both the amino acid L-lysine and the diamine putrescine from glucosamine was demonstrated.

Transcription of Sialic Acid Catabolism Genes in Corynebacterium glutamicum Is Subject to Catabolite Repression and Control by the Transcriptional Repressor NanR

“…1, Neu5Ac is then metabolized by the consecutive action of the N-acetylneuraminic acid lyase NanA (encoded by cg2931 [nanA]), the N-acetylmannosamine kinase NanK (encoded by cg2932 [nanK]), the N-acetylmannosamine-6-phosphate epimerase NanE (encoded by cg2935 [nanE]), the N-acetylglucosamine-6-phosphate deacetylase NagA (encoded by cg2929 [nagA]), and the glucosamine-6-phosphate deaminase NagB (encoded by cg2928 [nagB]) to pyruvate, acetate, ammonia, and fructose-6-phosphate (fructose-6P) (22). The enzyme NagB is also required for utilization of glucosamine as a source of carbon and nitrogen, which is taken up via the glucose specific permease EII Glc of the phosphoenolpyruvate sugar phosphotransferase system (PTS) (24). For the efficient utilization of glucosamine by C. glutamicum increased expression of nagB is required, which is brought about either by ectopic expression or by a point mutation within the promoter region of the nagAB operon in the spontaneous mutant C. glutamicum M4 (24).…”

“…The enzyme NagB is also required for utilization of glucosamine as a source of carbon and nitrogen, which is taken up via the glucose specific permease EII Glc of the phosphoenolpyruvate sugar phosphotransferase system (PTS) (24). For the efficient utilization of glucosamine by C. glutamicum increased expression of nagB is required, which is brought about either by ectopic expression or by a point mutation within the promoter region of the nagAB operon in the spontaneous mutant C. glutamicum M4 (24). The genes for Neu5Ac utilization are organized in C. glutamicum in three clustered operons, namely, nagAB, nanAKE, and siaEFGI.…”

Transcription of malP is subject to phosphotransferase system-dependent regulation in Corynebacterium glutamicum

“…Data represent mean values and SDs from three independent cultivations with three technical replicates. Uhde et al, 2013;Youn et al, 2008Youn et al, , 2009. No mutations were observed in sequence analyses of the malP promoter region, as well as of the malP gene itself, in DNA preparations from C. glutamicum HSM; thus, no evidence for cis-acting mutations was found.…”

“…In addition to its primary function for sugar uptake and phosphorylation, the PTS participates in various bacteria in the control of diverse cellular functions, such as catabolite repression, chemotaxis and control of pathogenesis (Deutscher et al, 2006(Deutscher et al, , 2014Gabor et al, 2011;Görke & Stülke, 2008 Uhde et al, 2013), hitherto no regulatory functions of the PTS were described in this organism. Slowed-down growth of PTS-deficient C. glutamicum strains on maltose already had been observed by Parche et al (2001).…”

“…The PTS components enzyme I (EI), HPr and four enzyme II permeases were identified and analysed (Moon et al, 2005;Parche et al, 2001). Of the latter, the ptsG-encoded EIIBCA Glc catalyses uptake and phosphorylation of both glucose and glucosamine, the ptsF-and ptsS-encoded permeases EIIABC Fru and EIIBCA Suc fructose and sucrose uptake, respectively (Moon et al, 2005;Uhde et al, 2013). Albeit a serine residue is present at position 46 in C. glutamicum HPr (Fig.…”