Transcriptional regulation of histidine biosynthesis genes in Corynebacterium glutamicum

Research Center for Women's Diseases, Sookmyung Women's University, Seoul, Korea.
Canadian Journal of Microbiology (Impact Factor: 1.22). 02/2010; 56(2):178-87. DOI: 10.1139/w09-115
Source: PubMed


Corynebacterium glutamicum, a gram-positive bacterium, has been widely used for industrial amino acid production. Corynebacterium glutamicum his genes are located and transcribed in two unlinked loci, hisEG and hisDCB-orf1-orf2-hisHA-impA-hisFI. The latter his operon starts the transcription at the C residue localized 196 bp upstream of the hisD ATG start codon. Our computer-based sequence analysis showed that the region corresponding to the untranslated 5' end of the transcript, named the hisD leader region, displays the typical features of the T-box transcriptional attenuation mechanism. Therefore, expression of the cat reporter gene under the control of the wild-type or mutated hisD leader regions was tested in multi-copy (pProm and pTer series) and in single-copy (pInt series) systems under conditions of sufficient or limited histidine. Our mutational studies led to the conclusion that the CAU histidine specifier and 5'-UGGA-3' sequence in the hisD leader region are required for the hisDCB-orf1-orf2-hisHA-impA-hisFI gene regulation. The cat gene expression from the wild-type leader region was negatively regulated by histidine. However, the cat gene expression from mutated leader regions was irresponsive to the level of histidine in the growth medium. Taken together, we propose that a T-box mediated attenuation mechanism is responsible for the gene expression of the hisDCB-orf1-orf2-hisHA-impA-hisFI operon in C. glutamicum.

14 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bacteria of the Geobacter clade possess two distinct ATP phosphoribosyltransferases encoded by hisG(L) and hisG(S)+hisZ to catalyze the first reaction of histidine biosynthesis. This very unusual redundancy was investigated by mutational analysis. The hisG(L), hisG(S), and hisZ genes of Geobacter sulfurreducens were deleted, effects on growth and histidine biosynthesis gene expression were evaluated, and deficiencies were complemented with plasmid-borne genes. Both hisG(L) and hisG(S)+hisZ encode functional ATP phosphoribosyltransferases. However, deletion of hisG(L) resulted in no growth defect, whereas deletion of hisG(S) delayed growth when histidine was not provided. Both deletions increased hisZ transcript abundance, and both ΔhisG(S) and ΔhisZ mutations increased hisG(L) transcript abundance. Growth with HisG(L) alone (due to deletion of either hisG(S) or hisZ) was better under nitrogen fixation conditions than when ammonium was provided. Deletion of hisZ caused growth defects under all conditions tested, with or without exogenous sources of histidine, with different patterns of histidine biosynthesis gene expression under each condition. Taken together, the data indicate that G. sulfurreducens depends primarily on the HisG(S)Z isozyme as an ATP phosphoribosyltransferase in histidine biosynthesis, and for other functions when histidine is available; however, HisG(L) also functions as ATP phosphoribosyltransferase, particularly during nitrogen fixation.
    No preview · Article · Jul 2011 · Canadian Journal of Microbiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Histidine biosynthesis in Corynebacterium glutamicum is regulated not only by feedback inhibition by the first enzyme in the pathway, but also by repression control of the synthesis of the histidine enzymes. C. glutamicum histidine genes are located and transcribed in two unlinked loci, hisEG and hisDCB-orf1-orf2-hisHA-impA-hisFI. We constructed plasmid pK18hisDPtac to replace the native hisD promoter with the tac promoter, and overexpressed phosphoribosyl-ATP-pyrophosphohydrolase, encoded by hisE, and ATP-phosphoribosyltransferase, encoded by hisG. The L-histidine titer at 0.85 g l(-1) was 80 % greater in the transformed bacterium and production of byproducts, L-alanine and L-tryptophan, was significantly decreased. However, accumulation of glutamic acid increased by 58 % (2.8 g l(-1)). This study represents the first attempt to substitute the histidine biosynthesis pathway promoter in the chromosome with a stronger promoter to increase histidine production.
    No preview · Article · Jan 2013 · Biotechnology Letters
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: l-Histidine biosynthesis is an ancient metabolic pathway present in bacteria, archaea, lower eukaryotes, and plants. For decades l-histidine biosynthesis has been studied mainly in Escherichia coli and Salmonella typhimurium, revealing fundamental regulatory processes in bacteria. Furthermore, in the last 15 years this pathway has been also investigated intensively in the industrial amino acid-producing bacterium Corynebacterium glutamicum, revealing similarities to E. coli and S. typhimurium, as well as differences. This review summarizes the current knowledge of l-histidine biosynthesis in C. glutamicum. The genes involved and corresponding enzymes are described, in particular focusing on the imidazoleglycerol-phosphate synthase (HisFH) and the histidinol-phosphate phosphatase (HisN). The transcriptional organization of his genes in C. glutamicum is also reported, including the four histidine operons and their promoters. Knowledge of transcriptional regulation during stringent response and by histidine itself is summarized and a translational regulation mechanism is discussed, as well as clues about a histidine transport system. Finally, we discuss the potential of using this knowledge to create or improve C. glutamicum strains for the industrial l-histidine production.
    Full-text · Article · Apr 2013 · Microbial Biotechnology
Show more