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

Abstract

The Gram-positive Corynebacterium glutamicum co-metabolizes most carbon sources such as the phosphotransferase system (PTS) sugar glucose and the non-PTS sugar maltose. Maltose is taken up via the ABC-transporter MusEFGK 2 I, and is further metabolized to glucose phosphate by amylomaltase MalQ, maltodextrin phosphorylase MalP, glucokinase Glk and phosophoglucomutase Pgm. Surprisingly, growth of C. glutamicum strains lacking the general PTS components EI or HPr was strongly impaired on the non-PTS sugar maltose. Complementation experiments showed that a functional PTS phosphorelay is required for optimal growth of C. glutamicum on maltose, implying its involvement in the control of maltose metabolism and/or uptake. To identify the target of this PTS-dependent control, transport measurements with 14 C-labelled maltose, Northern blot analyses and enzyme assays were performed. The activities of the maltose transporter and enzymes MalQ, Pgm and GlK were not decreased in PTS-deficient C. glutamicum strains, which was corroborated by comparable transcript amounts of musE, musK and musG, as well as of malQ, in C. glutamicum DptsH and WT. By contrast, MalP activity was significantly reduced and only residual amounts of malP transcripts were detected in C. glutamicum DptsH when compared to WT. Promoter activity assays with the malP promoter in C. glutamicum DptsH and WT confirmed that malP transcription is reduced in the PTS-deficient strain. Taken together, we show here for what is to the best of our knowledge the first time a regulatory function of the PTS in C. glutamicum and identify malP transcription as its target.

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

“…The presence of preferred substrates results in HPrK-catalyzed phosphorylation of the PTS component HPr at Ser-46, which, in turn, binds to and activates CcpA, and the resulting CcpA and P-Ser46-HPr complex then binds to DNA, which leads to repression of target promoters (71,78). Although a serine residue is indeed present at position 46 in C. glutamicum HPr, it is unlikely that a CcpA-like mechanism underlies the observed repression of Neu5Ac catabolism in C. glutamicum in the presence of glucose or fructose, as neither a gene for nor activity of HPrK was detected in C. glutamicum (79,80). In the Gram-negative bacteria V. vulnificus and H. influenzae, CCR is brought about by the cyclic AMP (cAMP) receptor protein (CRP) (37,39,43).…”

La répression catabolique ou comment les bactéries choisissent leurs sucres préférés

“…Il est à noter que, chez l'actinobactérie Corynebacterium glutamicum, le métabolisme du maltose est fortement altéré chez un mutant ptsH, dont le gène codant la protéine HPr a été délété, bien que le disaccharide soit incorporé via le transporteur ABC. En fait, la délétion de ptsH s'avère inhiber spécifiquement l'expression du gène malP qui code la maltose phosphorylase [37]. Toutefois, les mécanismes moléculaires de cette régulation ne sont pas encore connus.…”

Application of Corynebacterium glutamicum engineering display system in three generations of biorefinery

“…The transport of many hexoses is involved in the phosphorylation cycle of the PTS system [ 62 ]. Pts are composed of two common energy-coupling cytoplasmic proteins, enzyme I (EI) and histidine-containing phosphor carrier protein (HPr), which are encoded by ptsI (NCgl1858) and ptsH (NCgl1862), respectively, and a series of sugar-specific enzyme II complexes (EII) [ 63 – 65 ]. Currently, four sets of PTSs have been identified in C. glutamicum , each of these PTSs is specific for a different substrate and those identified are specific for glucose, fructose, sucrose, and an unknown substrate [ 66 ].…”