Identification of lactate dehydrogenase as a mammalian pyrroloquinoline quinone (PQQ)-binding protein

Abstract

Pyrroloquinoline quinone (PQQ), a redox-active o-quinone, is an important nutrient involved in numerous physiological and biochemical processes in mammals. Despite such beneficial functions, the underlying molecular mechanisms remain to be established. In the present study, using PQQ-immobilized Sepharose beads as a probe, we examined the presence of protein(s) that are capable of binding PQQ in mouse NIH/3T3 fibroblasts and identified five cellular proteins, including l-lactate dehydrogenase (LDH) A chain, as potential mammalian PQQ-binding proteins. In vitro studies using a purified rabbit muscle LDH show that PQQ inhibits the formation of lactate from pyruvate in the presence of NADH (forward reaction), whereas it enhances the conversion of lactate to pyruvate in the presence of NAD+ (reverse reaction). The molecular mechanism underlying PQQ-mediated regulation of LDH activity is attributed to the oxidation of NADH to NAD+ by PQQ. Indeed, the PQQ-bound LDH oxidizes NADH, generating NAD+, and significantly catalyzes the conversion of lactate to pyruvate. Furthermore, PQQ attenuates cellular lactate release and increases intracellular ATP levels in the NIH/3T3 fibroblasts. Our results suggest that PQQ, modulating LDH activity to facilitate pyruvate formation through its redox-cycling activity, may be involved in the enhanced energy production via mitochondrial TCA cycle and oxidative phosphorylation.

Pyrroloquinoline quinone prevents developmental programming of microbial dysbiosis and macrophage polarization to attenuate liver fibrosis in offspring of obese mice

“…Despite continuous feeding with WD postnatally, early exposure to di‐sodiated PQQ attenuated the development of liver injury and fibrosis through mechanisms that appear to involve restoration of oxidative metabolism in macrophages and retention of an early life microbial composition. In addition to its antioxidant action, PQQ is a noted potentiator of oxidoreductase activity, both in bacteria and mammals, and promotes oxidative metabolism through modulation of lactate dehydrogenase activity . The increased abundance of citrate in BMDMs following stimulation combined with the augmented response in WD‐fed mice with rescue by in vitro addition of PQQ suggests that reprogramming of the TCA cycle at isocitrate dehydrogenase may be attenuated by PQQ.…”

Sperm enrichment from poor semen samples by double density gradient centrifugation in combination with swim-up for IVF cycles

“…Previous studies in rodents showed that increased centrifugation force would damage the cell organelles and membranes of sperm [10][11][12] . However, few studies have been conducted to further explore the effect of the sperm suffering excess centrifugation force on the outcomes of IVF in any species.…”

“…However, few studies have been conducted to further explore the effect of the sperm suffering excess centrifugation force on the outcomes of IVF in any species. Only one study showed that rat sperm with over centrifugation had no impact on the fertilization rate 12 . In line with that, we also found that double centrifugation did not decrease the fertilization rate, nor the other indicators mentioned above.…”

“…It has been demonstrated that an increase in the centrifugation time or gravitational (g) force can increase the sperm recovery rate from equine semen but can also decrease sperm motility or quality due to the mechanical forces associated with centrifugation and excessive packing of the sperm 9 . Studies using spermatozoa from the epididymis of rats and mice revealed that increasing the centrifugation force decreased sperm function [10][11][12] . A previous study demonstrated that centrifugation stress reduces the responsiveness of the spermatozoa of pigs to a capacitation stimulus 13 .…”

WD 40 domain of RqkA regulates its kinase activity and role in extraordinary radioresistance inDeinococcus radiodurans

“…The loss of γ radiation mediated activation of RqkA in the DpqqE mutant and absence of γ 381 radiation response of RqkA KD autophosphorylation suggest the importance of both WD40 382 domain and PQQ in the activation of RqkA function in response to γ radiation and DNA 383 damage-induced signaling through RqkA. PQQ has recently been shown to physically 384 interact with cellular proteins in the mammalian system and crucial for the regulation of their 385 enzymatic activity(Akagawa et al, 2016). RqkA phosphorylates DNA repair and cell 386 division proteins in response to gamma radiation and DNA damage (Rajpurohit and Misra, 387 2013a,Rajpurohit et al, 2016.…”