Significance of the Cgl1427 gene encoding cytidylate kinase in microaerobic growth of Corynebacterium glutamicum

Abstract

The Cgl1427 gene was previously found to be relevant to the microaerobic growth of Corynebacterium glutamicum (Ikeda et al. 2009). In the present work, Cgl1427 was identified as a cytidylate kinase gene (cmk) by homology analysis of its deduced amino acid sequence with that of other bacterial cytidylate kinases (CMP kinases), and on the basis of findings that deletion of Cgl1427 results in loss of CMP kinase activity. Deletion of the cmk gene significantly impaired the growth of C. glutamicum in oxygen-limiting static culture, and the impaired growth was restored by introducing a plasmid containing the cmk gene, suggesting that this gene plays an important role in microaerobic growth of C. glutamicum. On the other hand, in the main culture with aerobic shaking, a prolonged lag phase was observed in the cmk disruptant, despite an unchanged growth rate, compared to the behavior of the wild-type strain. The prolongation was observed when using seed culture grown to later growth stages in which oxygen limitation occurred, but not observed when using seed culture grown to an earlier growth stage in which oxygen remained relatively plentiful. Since nucleotide biosynthesis in C. glutamicum requires oxygen, we hypothesized that the ability of the 3 cmk disruptant to synthesize nucleotides was influenced by oxygen limitation in the later growth stages of the seed culture, which caused the prolongation of the lag phase in the following shaken culture. To verify this hypothesis, a plasmid containing genes encoding all components of a homologous ribonucleotide reductase, a key enzyme for nucleotide synthesis that requires oxygen for its reaction, was introduced into the cmk disruptant, which significantly ameliorated the lag phase prolongation. Furthermore, this experimental setup almost completely restored the growth of the cmk disruptant in the oxygen-limiting static culture. These results indicate that CMP kinase plays an important role in normal nucleotide biosynthesis under an oxygen-limiting environment.

Comparative Genomics and Phylogenomics of Hemotrophic Mycoplasmas

“…Therefore, it is unknown if dCTP/CTP is produced from cytosine and/or uracil residues in hemoplasmas. Recently, cytidylate kinase has been described to have a positive impact on the efficiency of nucleotide synthesis in Corynebacterium glutamicum under microaerobic conditions [49]. Whether or not the presence of this enzyme favors the survival of M. haemofelis and M. haemocanis in oxygen-limited environments needs to be further explored.…”

A Novel Peptide Nucleic Acid against the Cytidine Monophosphate Kinase of S. aureus Inhibits Staphylococcal Infection In Vivo

“…Supporting this notion, the cmk and deoD genes encode cytidine monophosphate kinase and purine nucleoside phosphorylase, respectively, 20 which are involved in nucleotide biosynthesis, one of the most important metabolic pathways. Previous studies suggested that both genes are required for the growth of several bacterial species, such as Corynebacterium glutamicum , Bacillus subtilis , and E. coli ,22, 23 and thus considered as potential therapeutic drug targets 24 …”

Genomics Characterization of an Engineered Corynebacterium glutamicum in Bioreactor Cultivation Under Ionic Liquid Stress

“…Of the genes uniquely downregulated at 6.5 h, included Cgl1427/ cmk, cytidyl kinase, Cgl2605/ bioD, thioredoxin reductase. Cgl1427 has been reported to be crucial for maintaining triphosphate pools (ATP, CTP) under oxygen-limiting environments ( Takeno et al, 2013 ) but it’s downregulation implies these early time points are not oxygen-limited. Several genes involved in transport were also significantly downregulated with a cutoff threshold log 2 ratio less than −4.…”