RESUMO
The existence of a K+ cycle in mitochondria has been predicted since the development of the chemiosmotic theory and has been shown to be crucial for several cellular phenomena, including regulation of mitochondrial volume and redox state. One of the pathways known to participate in K+ cycling is the ATP-sensitive K+ channel, MitoKATP. This channel was vastly studied for promoting protection against ischemia reperfusion when pharmacologically activated, although its molecular identity remained unknown for decades. The recent molecular characterization of MitoKATP has opened new possibilities for modulation of this channel as a mechanism to control cellular processes. Here, we discuss different strategies to control MitoKATP activity and consider how these could be used as tools to regulate metabolism and cellular events.
Assuntos
Mitocôndrias/metabolismo , Potássio/metabolismo , Animais , Humanos , Transporte de Íons , Modelos Biológicos , Canais de Potássio/metabolismo , Antiportadores de Potássio-Hidrogênio/metabolismoRESUMO
Maintenance of the inward transport of potassium (K) by roots is a critical step to ensure K-nutrition for all plant tissues. When plants are grown at low external K concentrations a strong enhancement of the activity of the AtHAK5 transporter takes place. In a recent work, we observed that the gai-1 mutant of Arabidopsis thaliana, which bears an altered function version of a DELLA regulatory protein, displays reduced accumulation of AtHAK5 transcripts and reduced uptake of Rubidium, an analog for K. In this Addendum we discuss some hypotheses and uncertainties regarding how DELLAs could contribute to the control of K uptake under those conditions. We advance the idea that, following K-restriction, there is a zone and tissue specific regulation of DELLAs by gibberellins through a pathway that likely involves ethylene. According to this model in the epidermis of non-apical zones, DELLAs repress transcription factors that promote AtHAK5 accumulation.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Potássio/metabolismo , Regulação da Expressão Gênica de Plantas , Antiportadores de Potássio-Hidrogênio/metabolismoRESUMO
The KT/HAK/KUP family members encoding high-affinity potassium (K(+)) transporters mediate K(+) transport across the plasma membranes of plant cells to maintain plant normal growth and metabolic activities. In this paper, we identified 16 potassium transporter genes in the peach (Prunus persica) using the Hidden Markov model scanning strategy and searching the peach genome database. Utilizing the Arabidopsis KT/HAK/KUP family as a reference, phylogenetic analysis indicates that the KT/HAK/KUP family in the peach can be classified into 3 groups. Genomic localization indicated that 16 KT/HAK/KUP family genes were well distributed on 7 scaffolds. Gene structure analysis showed that the KT/HAK/KUP family genes have 6-9 introns. In addition, all of the KT/HAK/KUP family members were hydrophobic proteins; they exhibited similar secondary structure patterns and homologous tertiary structures. Putative cis-elements involved in abiotic stress adaption, Ca(2+) response, light and circadian rhythm regulation, and seed development were observed in the promoters of the KT/HAK/KUP family genes. Subcellular localization prediction indicated that the KT/HAK/KUP members were mainly located in the plasma membrane. Expression levels of the KT/HAK/ KUP family genes were much higher in the fruit and flower than those in the other 7 tissues examined, indicating that the KT/HAK/KUP family genes may have important roles in K(+) uptake and transport, which mainly contribute to flower formation and fruit development in the peach.