Abstract
Several recent investigations have demonstrated that members of the KCTD (Potassium Channel Tetramerization Domain) protein family are involved in fundamental processes. However, the paucity of structural data available on these proteins has frequently prevented the definition of their biochemical role(s). Fortunately, this scenario is rapidly changing as, in very recent years, several crystallographic structures have been reported. Although these investigations have provided very important insights into the function of KCTDs, they have also raised some puzzling issues. One is related to the observation that the BTB (broad-complex, tramtrack, and bric-à-brac) domain of these proteins presents a remarkable structural versatility, being able to adopt a variety of oligomeric states. To gain insights into this intriguing aspect, we performed extensive molecular dynamics simulations on several BTB domains of KCTD proteins in different oligomeric states (monomers, dimers, tetramers, and open/close pentamers). These studies indicate that KCTD-BTB domains are stable in the simulation timescales, even in their monomeric forms. Moreover, simulations also show that the dynamic behavior of open pentameric states is strictly related to their functional roles and that different KCTDs may form stable hetero-oligomers. Molecular dynamics (MD) simulations also provided a dynamic view of the complex formed by KCTD16 and the GABAB2 receptor, whose structure has been recently reported. Finally, simulations carried out on the isolated fragment of the GABAB2 receptor that binds KCTD16 indicate that it is able to assume the local conformation required for the binding to KCTD.
Highlights
Studies carried out in the last decade have demonstrated that members of the KCTD family, proteins containing a Potassium (K) Channel Tetramerization Domain, are involved in fundamental physiopathological processes [1,2,3,4,5]
Simulations provided a dynamic view of the complex formed by KCTD16 and the GABAB2 receptor, whose structure has been recently reported
KCTD11 is involved in the etiology of medulloblastoma [6], KCTD7 in epilepsy [7], KCTD2/KCTD5/INC in sleep homeostasis [8,9,10], KCTD8/12/16 in GABAB receptor (GABAB R) modulation [11], while KCTD13 is believed to play an important role in autism [12,13]
Summary
Studies carried out in the last decade have demonstrated that members of the KCTD family, proteins containing a Potassium (K) Channel Tetramerization Domain, are involved in fundamental physiopathological processes [1,2,3,4,5]. KCTD11 is involved in the etiology of medulloblastoma [6], KCTD7 in epilepsy [7], KCTD2/KCTD5/INC in sleep homeostasis [8,9,10], KCTD8/12/16 in GABAB receptor (GABAB R) modulation [11], while KCTD13 is believed to play an important role in autism [12,13]. These proteins play key roles in other processes that include obesity [14], breast carcinoma [15], and SEN syndrome [16,17]. From the molecular point of view, KCTDs are Biomolecules 2019, 9, 323; doi:10.3390/biom9080323 www.mdpi.com/journal/biomolecules
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