Regulation of Coenzyme A Biosynthesis in the Hyperthermophilic Bacterium Thermotoga maritima

Abstract

Regulation of coenzyme A (CoA) biosynthesis in bacteria and eukaryotes occurs through feedback inhibition targeting type I and type II pantothenate kinase (PanK), respectively. In contrast, the activity of type III PanK is not affected by CoA. As the hyperthermophilic bacterium Thermotoga maritima harbors only a single type III PanK (Tm-PanK), here we examined the mechanisms that regulate CoA biosynthesis in this organism. We first examined the enzyme responsible for the ketopantoate reductase (KPR) reaction, which is the target of feedback inhibition in archaea. A classical KPR homolog was not present on the T. maritima genome, but we found a homolog (TM0550) of the ketol-acid reductoisomerase (KARI) from Corynebacterium glutamicum, which exhibits KPR activity. The purified TM0550 protein displayed both KPR and KARI activities and was designated Tm-KPR/KARI. When T. maritima cell extract was subjected to anion-exchange chromatography, the fractions containing high levels of KPR activity also displayed positive signals in a Western blot analysis using polyclonal anti-TM0550 protein antisera, strongly suggesting that Tm-KPR/KARI was the major source of KPR activity in the organism. The KPR activity of Tm-KPR/ KARI was not inhibited in the presence of CoA. We thus examined the properties of Tm-PanK and the pantothenate synthetase

Mosaic Evolution of the Phosphopantothenate Biosynthesis Pathway in Bacteria and Archaea

“…The use of the archaeal rather than the bacterial reaction order for the synthesis of the CoA intermediate d -4′-phosphopantothenate in the symbiotic Entoporibacteria group mirrors what has been shown in the archaea Picrophilus torridus , in which an enzyme much closer to the bacterial PanK than to the canonical archaeal PoK was found and has been annotated as “archaeal PanK” ( Takagi et al. 2010 ; Shimosaka et al. 2016 ).…”

“…However, in the two bacteria Corynebacterium glutamicum and Thermotoga maritima that also lack a classical KPR, it has been demonstrated that this activity is performed by the ketol-acid reductoisomerase (KARI) encoded by the ilvC gene, an enzyme classically involved in the biosynthesis of branched-chain amino acids ( Merkamm et al. 2003 ; Shimosaka et al. 2016 ).…”

A d-Phenylalanine-Benzoxazole Derivative Reveals the Role of the Essential Enzyme Rv3603c in the Pantothenate Biosynthetic Pathway of Mycobacterium tuberculosis

“…Loss of ilvC causes pantothenate auxotrophy in Corynebacterium glutamicum, a close relative of Mtb 35 , and IlvC is the only KPR in Thermotoga maritima 36 . These observations demonstrate that IlvC is the only protein with KPR activity in some bacteria.…”

The coenzyme A biosynthetic pathway: A new tool for prodrug bioactivation

“…Other unique biochemical traits of PanKIII include the requirement for a monovalent cation such as NH4 + or K + [31], and no appreciable affinity for pantothenamides [30]. TmPanKIII was reported to experience negative CoA feedback, with complete inhibition at about 400 µM of CoA [41], whereas Helicobacter pylori PanKIII and Bacillus subtilis PanKIII are not affected by CoA or its thioesters [30], suggesting heterogeneity in regulation within PanK types. PanKIII isoforms can be found across almost all phyla of bacteria [9], and typically have a high KM for ATP (PanKIII KM: B. anthracis = 510 µM [42], B. subtilis = 3.1 mM [30], H. pylori = 7.9-9.6 mM [30,40], T. maritima = 6.0 mM at 50 o C [9]), and little affinity for other phosphate donors [31].…”