Role of Succinate Dehydrogenase in Cellular Respiration

Succinate dehydrogenase, also known as electron transport chain complex II, has recently experienced a notable and focused resurgence in research. Despite being the least explored among the mitochondrial respiratory complexes, this complex has gained renewed attention owing to its identified role in human diseases. This heightened examination has unveiled succinate dehydrogenase as an intriguing apparatus, with its regulation and assembly involving newly emerging factors. Managing within the citric acid cycle, SDH acquires electrons and passes them through its four subunits, namely SDHA, SDHB, SDHC, and SDHD, enabling electron transfer in the ETC as complex II. The electrons from reduced ubiquinone and FADH[[inf]]2[[/inf]] are subsequently taken into the complex III to produce a sustainable flow of ATPs, thus supplying energy for the cell. The precise regulation of this enzyme through its diverse complexes enables cells to carry out crucial functions such as cellular respiration, hypoxic response, and gene expression. The distinct functionalities of various subunits within the SDH complex can account for these metabolic alterations. Therefore, various human disorders are caused due to mutations found in these factors and the structural components of the complex. However, deviations in SDH activity can lead to diseases and development of carcinogenicity due to disruptions in electron flow, heightened oxygen toxicity, and accumulation of succinate. Through this chapter, we delve deeper into the insights of mechanisms that underlie the pathology resulting from these SDH mutations.