Journal of Proteomics & Bioinformatics
Open Access
ISSN: 0974-276X
ISSN: 0974-276X
Subin Kim, Ji Won Kim, Haerim Lee, Songwon Kim, Jie-Oh Lee and Mi Sun Jin
KAIST, Korea
SGIST, Korea
Posters & Accepted Abstracts: J Proteomics Bioinform
The 2-HCT family of transporters generally translocate molecules with a 2-hydroxycarboxylate motif (HO-CR1R2-COO-), such as citrate, malate and lactate across the plasma membrane, and activity is tightly coupled to energy from a sodium or proton gradient. Klebsiella pneumoniae CitS (KpCitS) is the best-characterized model system, which has been purified in detergent and characterized in a reconstituted state. It plays a key role for citrate uptake to ultimately produce ATP in anaerobic fermentative process. Single-molecule fluorescence spectroscopy study provided an evidence for formation of homodimeric KpCitS. Analysis of hydropathy profiles and rich biochemical data suggested that it consists of 11 transmembrane helixes with two putative reentrant loops. Mutational studies showed that R428, which is strictly conserved in transporters of the 2-HCT family, is critical for interaction with one of the carboxylate groups of citrate. Analysis of data from kinetics experiments demonstrated that KpCitS carries citrate followed by binding of sodium ion. However, there are conflicting data regarding exact stoichiometry. The structure of KpCitS was studied extensively by electron crystallography, providing a glimpse of its global structure. The crystal structure of a homologous symporter from Salmonella enterica (SeCitS) recently revealed that it forms an asymmetric dimer, and that each protomer embeds a substrate translocation pathway at the interface between the transport and the dimerization domains. That structure provided the first high resolution view of a member of the 2-HCT family; however, many details in the transport cycle remained unanswered.
Subin Kim graduated from Chonnam National University in 2014 and completed her MS from Gwangju Institute of Science and Technology (GIST) in 2016 and she joined as PhD candidate in School of Life Sciences at Gwangju Institute of Science and Technology (GIST) under Mi Sun Jin in 2016.